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114 Cards in this Set
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Importance of vitamins
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-Organic molecules required in minute amounts for normal function, growth, and maintenance of body tissues
-Compound primarily of C and H but may also contain oxygen, P, Co, S and other elements -Function as cofactors in enzyme reactions that synthesize important chemicals for body functions -Roles in calcium balance and in the extraction of energy from CHO, fat and protein -Livestock require only 14 vitamins, not all are dietary essentials for all species -Some are synthesized within animal tissue and some are synthesized and made available to ruminant livestock by microbes inhabiting the digestive tract. Monogastrics don't synthesize enough to meet their requirements |
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Classification of vitamins
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Fat soluble: A, E, D and K
Water soluble: B and C |
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Vitamin content in plants affected by:
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-Harvesting
-processing -storage -plant species -plant parts |
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Vitamin Potency
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-The daily requirements for all vitamins except A, D and E are expressed in milligrams or micrograms
-Daily requirements for vitamins A, D and E are expressed in units of potency -Potency refers to the ability of the source of vitamin to remove signs of vitamin deficiency. |
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Vitamin supplementation
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-Vitamins that livestock require can be supplied through:
-consumption of fresh feedstuffs rich in vitamin content -addition of vitamins to the ration -injection of vitamins |
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Vitamin stability
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-Vitamins are destroyed by: heat, sunlight, oxidizing conditions and mold growth
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Fat soluble vitamins
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-Storage for fat soluble vitamins is significant because body fat isn't turned over as often as water
-Deficiency of fat soluble vitamins may not immediately occur because stored vitamins will be used first -Absorption is similar to lipid absorption |
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Vitamin A sources
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-Pure forms of vitamin A may be found in animal tissues and animals products (liver, milk, eggs, etc)
-Carotene is the form of vitamin A in fresh plant material. They are converted to vitamin A with varying efficiencies across species. Poultry have very high capacity to do this conversion -Supplemental vitamin A sol in dry, gelatin-coated form to which antioxidants have been added -Carrots, strawberries, milk, eggs, fish, etc. |
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Vitamin A functions
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-Maintenance of epithelial tissue
-Night vision -Glycoprotein (in cell membrane) synthesis |
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VItamin A deficiencies
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-Night blindness
-reduced growth -reproduction problems -extensive keratinization -bone-shape abnormalities -hind-leg paralysis |
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Hyper-vitaminosis A
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-Prolonged intake of excess vitamin A
-rough hair coat -skin cracks -tremors -hyper-irritability -bone fragility |
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Vitamin A benefits
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-Maintains health of specialized tissues such as the retina
-aids in growth and health of skin and mucous membranes -promotes normal development of teeth, soft and skeletal muscle |
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Vitamin D sources
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-All vitamin D required may be obtained from UV light with the exception of fish
-D 2 (ergocalciferol) comes from plant soucres -D 3 (cholecalciferol) comes from animal sources -Poultry and fish poorly utilize D2 -Supplemental vitamin D3: fish oils and made by irradiation of animal sterol -Cheese, butter, fortified milk and cereals and fish |
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Vitamin D functions
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-To facilitate mobilization, transport, absorption, and use of calcium and phosphorous
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Vitamin D deficiencies
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-Disturbance in calcium and phosphorous absorption and metabolism
-Rickets in young animals due to inefficient bone mineralization -Osteoporosis in adult animals due to diminished mineral content of bone -Parturient paresis-milk fever in cows |
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Hyper-vitaminosis D
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-Prolonged intake of excess vitamin D can lead to calcification of the soft tissues of the body including the heart muscle, kidney, and lung.
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Vitamin E sources
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-Natural sources are vegetable oils, generally supplemented to level required using one of the tocopheryl or tocopherol compounds.
-Corn, nuts, olives, green leafy vegetables, etc. |
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Vitamin E functions
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-Normal reproductive function in male and female animals
-Antioxidant to protect the lipids in cell membranes from oxidation (like selenium). These nutrients appear to have a sparing effect on one another. Animals receiving diets that are marginal in either vitamin E or selenium will respond to additional amounts of the other nutrient |
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Vitamin E deficiencies
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-Muscle degeneration
-Anemia -liver problems -digestive disorders -impaired immune function -sudden death |
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Vitamin K sources
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-Founf naturally in both animal tissues and plant material
-Synthetic vitamin K-menadione, is extremely unstable, so pure vitamin K is not utilized in feed industry -Many forms of vitamin K have improved stability -Primarily from bacterial synthesis in the GI tract of animals, but monogastrics don't synthesize enough -Cabbage, cauliflower, spinach, and other leafy green vegetables |
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Vitamin K function
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-Used in the body's blood-clotting mechanism
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Vitamin K deficiencies
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-Reduced ability to form clots, and may result in unchecked internal hemorrhages
-Antibiotic therapy may result in vitamin K deficiency--microbes are major source of vitamin K and antibiotics could kill them -Dicumarol and rat poisoning |
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Water soluble vitamins
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-Soluble in water, so the body has the capacity of disposing of any excess through activities at the kidneys. This means problems due to excesses are unlikely but also means daily intake is essential
-Vitamin B and C -Good sources of water soluble: fish and milk by-products, oilseed meals, bran of cereal grain and roots |
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Thiamin (B1) sources
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-cereal grains, lean meats, milk and fortified breads
-microorganisms inhabiting the digestive tract of livestock synthesize thiamin |
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Thiamin function
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-Involved in nervous function
-participates in the production of ATP from food -aids the function of the heart and cardiovascular system |
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Thiamin deficiencies
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-appetite repression
-reduced weight gain -nervous disorders -heart-muscle degeneration -ruminants: polioencephalomalcia chicken: reproduction problems |
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Riboflavin (B2) sources
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-usually supplemented in pure form
-most likely to be deficient in unsupplemented diets made up of ingredients normally fed to herbivores -Much that exists in plant material has low bioavailability for most species -Made by microbes in digestive tracts of livestock -cereal, nuts, milk, eggs, green leafy vegetables and lean meat |
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Riboflavin function
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-Cofactor for many enzyme systems
-Red blood cell production -Production of ATP from organic molecules, release ATP from CHOs -Also functions as an antioxidant, like selenium, vitamin C and E |
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Riboflavin deficiencies
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-poor hair coat
-neurological problems -changes in blood composition -chicken: reproductive problems |
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Pyridoxine (B6) sources
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-Found naturally in most fresh feedstuffs
-It's destroyed by heat and some pyridoxine that exists in plant material -Micoorganisms in livestock digestive tracts synthesize pyridoxine -beans, legumes, nuts, eggs, meat, fish, breads and cereals |
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Pyridoxine (B6) functions
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-involved in metabolism of proteins
-cofactor of many enzyme systems, including those involved with the synthesis of neurotransmitters -Production of ATP -healthy brain function -Red blood cell formation -Synthesis of antibodies in support of the immune system |
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Pyridoxine deficiencies
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-Reduced growth rate
-impaired immune function -fatty liver -nervous disorders -blood composition changes |
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Cyanocobalamin (B12) sources
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-contains cobalt
-doesn't occur in plant materials so herbivores depend on the synthetic activity of microbes in their digestive tract for their supply of B12 -Because it contains cobalt, cobalt must be supplied in the diet if the animal's requirement is to be met through microbial synthesis -Monogastrics that have access to their feces can meet B12 requirements through coprophagy -Eggs, meat, poultry, shellfish, milk and milk products |
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Cyanocobalamin functions
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-Cofactor in many enzyme systems, including those involved with protein metabolism and DNA synthesis
-Production of ATP -important for metabolism -Red blood cell production -CNS maintenance |
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Cyanocobalamin deficiencies
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-poor hair coat
-kidney damage -reduced growth -nervous disorders -blood composition changes -chicken: reproduction problems |
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Pantothenic acid (B5) sources
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-found naturally in most fresh feedstuffs
-usually supplemented in monogastric diets because the level present in feedstuff and the bioavailability it unknown -Microorganisms in digestive tract of livestock synthesize it |
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Pantothenic acid functions
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-participates in production of ATP
-needed for maintenance of normal skin and health -fat metabolism -ketone synthesis |
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Pantothenic acid deficiencies
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-skin problems
-nervous disorders -digestive problems -impaired immune function -swime: abnormal gait called goose-stepping -chicken: reproduction problems |
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Niacin (B3) sources
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-supplements include nicotinic acid and nicotinamide
-relative to nicotinic acid, nicotinamide is 124% bioavailable for chicks -Niacin in corn, oats, wheat, and grain sorghum is in a bound form that is unavailable to monogastrics -Except in cats, niacin can be made metabolically from a dietary excess of tryptophan -micoorganisms in the digestive tract of livestock synthesize niacin -dairy, poultry, fish, lean meant, nuts and eggs |
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Niacin functions
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-production of ATP
-necessary to maintain normal skin health -healthy nerves -healthy digestive system |
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Niacin deficiencies
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-reduced growth
-digestive disturbances -skin problems -in lactating dairy cows, high levels have shown to reduce plasma ketone concentration and may help reduce incidence of ketosis; reduce fat mobilization -An inability to absorb niacin or tryptophan may cause pellagra, a disease characterized by scally sores, mucosal changes and mental symptoms |
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Folic acid (B9) sources
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-most fresh feedstuffs provide sufficient folic acid for most animals
-microorganisms in digestive tract of livestock synthesize folic acid -Monogastric animals that have access to their feced can meet folic acid requirement by coprophagy -Beans, legumes, citrus fruits, juices, whole grains, dark green leafy vegetables, poultry, pork, shellfish and liver |
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Folic acid functions
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-Red and white blood cell production
-conversion of serine to glycine which is important in chickens because they can't make enough glycine to support maximum growth -DNA synthesis -Works with cyanocobalamin and vitamin c to help body digest and utilize proteins |
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Folic acid deficiencies
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-changes in blood composition
-bone or cartilage development problems -poor skin conditions -chickens: reproduction problems |
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Biotin (B7) sources
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-most animals can synthesize vitamin c in their tissues from glucose and related compounds with exception of fish, guinea pigs and primates
-extremely labile and difficult to maintain in feed products, it's destroyed by many environmental factors. -fish: unprotected form of vitamin C are extruded -citrus fruits, green peppers, strawberries, tomatoes, broccoli and potatoes |
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Biotin functions
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-Antioxidant: helps protect lipids in cell membrane from destruction through reaction with oxygen
-facilitates iron absorption -AA metabolism and in growth and maintenance of bone and collagen -healthy immune system -wound healing -maintains blood vessels and connective tissue |
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Biotin deficiencies
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-structural deformities and abnormalities of supportive cartilage
-anemia and small hemorrhages -impaired wound healing, immune response and reproductive function -scurvy: weakness, anemia, bruising, bleeding gums and loose teeth |
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Factors influencing vitamin needs of livestock
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-environmental stress leading to animal strain, disease, or other conditions that lower intake and/or reduce intestinal absorption of vitamins
-disturbance of intestinal microflora -bioavailability and/or stability of various vitamin sources in certain feedstuffs -interrelationships of certain vitamins with other nutrients |
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Purpose of the sheep industry
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-Take advantage of forage to produce wool, meat and milk
-sheep are often part of mixed farms -large flocks that graze rangelands |
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Sheep terminology
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-Ram: intact male
-Ewe: female sheep -Wether:castrated male -Lamb:a male or female <1 year old |
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Causes for decline of sheep #s
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-steady decline after WWII
-less demand for wool -high cost and declining demand for lamb meat -decrease in reliable managers and herdsmen -increased competition for public-owned land -seasonal nature of lamb production -increasing number of predators -decreased gov't support -inadequate profit for farmers |
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Ewe: lactation
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-about 65 days
-peak 2-4 weeks postpartum -70% of milk in first 8 weeks -Ewes with twins make 20-40% more milk than those nursing singles -lambs weekend 6-10 weeks |
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Ewe: flushing/breeding
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-Practice of increasing nutrient intake (mostly energy, but also protein) at the time of breeding to improve ovulation rate and hence lambing rate
-10-20% improvement in lambing rate because of the effect on the developing follicles of the oary -greatest effect when body condition scores of 2.0-3.5 -move ewes onto high-quality pasture or feed grain -continue into breeding season to reduce embryonic death |
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ewe: mid/early gestation
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-gestation length is about 5 months
-ewes are fed to achieve a BCS of 3.5 at parturition -energy and nutrient requirements are low |
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ewe: late gestation
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-2/3 of fetal growth occurs at this time
-if ewe fed nutrient deficient diet, will have negative impacts on lambs: death low birth weight -dissimilar birth weights reduced number of wool follicles -..and milk production postpartum -ewes carrying twins or triplets will have greater nutrient requirements than ewes carrying singles -will mobilize body fat to meet these requirements if DMI is inadequate -pregnancy toxemia aka ketosis may result |
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lambs: creep feed
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-prevents ewe from eating the grain
-reduces stress on ewe with twins or triplets -may contain antibiotics to improve gain and feed efficiency |
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lambs: early weaning
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-lambs given colostrum then taken away from ere and fed milk replacer
-Advantages: increased weight gains market weight at younger age pasture-sparing less stress on ewe fewer problems with parasites and predators |
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lambs: growing/finishing
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-finishing diet about 80% grain
-ram lambs have higher DMI and nutrient requirements than ewe lambs |
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Nutrition and Wool Production
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-energy is the primary nutrient impacting wool production...limits synthesis of microbial protein
-wool follicles can be permanently damaged when pregnant ewe or lamb are not provided with adequate nutrition |
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Copper
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-sheep accumulate copper in liver more readily than most other species. Less than 25 ppm in diet
-Cu toxicity is a concern because it destroys liver cells -Molybdenum forms insoluble complex with Cu in s. intestine and prevents its absorption. This helps limit Cu absorption and prevent Cu toxicity. |
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Ruminal acidosis
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-acute: ruminal pH rapidly falls below 5.7
-subacute: ruminal pH 5.7-6.2 -damage to rumen wall allows bacteria to enter blood causing liver abscesses -histamine concentrations in rumen increase -histamine absorbed through rumen wall causes inflammation in the epithelial cells inside the hoof--laminitis |
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Enterotoxemia
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-'overeating disease'
-when stressed animals are presents with a diet change without a proper transition -clostridium and escherichia proliferate in s. intestine and produce toxins |
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White muscle disease
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-deficiency of selenium and/or vitamin E
-lambs 3-8 weeks of age are most often affected -symptoms: muscle stiffness in legs, pale heart and skeletal muscle -avoid by feeding adequate selenium and vitamin E or injecting them |
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Water
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-livestock require a greater quantity of water than feed daily
-production and health decline if water requirements are not met -water quality and water consumption by livestock should be monitored |
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Requirement for water
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-water is a nutrient and an important constituent of the animal's body and of animal products
-animal's requirement for water is influenced by: type of animal environmental temperature and humidity rate and composition of grain pregnancy lactation type of diet feed intake activity level |
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Functions of water
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-softening feed and preparing it for maceration and passage through the digestive tract
-hydrolysis -carrier: transporting nutrients and hormones, and allowing animal to void the waste products of metabolism -cooling the body temperature through evaporation from the body's surface and the respiratory system -maintains shape of body cells -important source of minerals |
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Three sources of water
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-drinking water: provide free access to clean, fresh water at all times
-water in feedstuffs: dry feeds contain 8-15%; high moisture grains contain 25-35%;silages contain 50-75%; pasture and green chop contain 80-90% -Metabolic water: water created within the body by living organisms during metabolism, by oxidizing energy-containing compounds in their foods. May account for 5 to 10% of total water intake |
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Factors affecting intake of water
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-Type of animal
-age and body weight -physiological state: activity level, rate and composition of gain, pregnancy, lactation -environmental temperature and humidity -dry matter intake -water quality -diet composition: water content of feed, fiber, salt, and protein content of the diet -older animal requires more water -if BW, activity, production or DMI increase, water requirement also increases -if diet has high protein concentration it would increase the water requirement because the animal needs water to get rid of the urea |
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Reasons for inadequate water consumption by livestock
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-limited accessibility
-frozen water sources -empty containers -inadequate flow rate -failure to adjust waters properly -poor water quality -stray voltage: voltage difference between two sources |
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Inadequate water intake
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Leads to:
-reduced DMI -reduced growth and performance -serious health problems |
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Six criteria for assessing quality of water sources
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-odor and taste
-pH, salinity, total dissolved solids (TDS), total dissolved oxygen and hardness -Presence of organic chemical contaminants, heavy metals, toxic minerals -presence of excess minerals or compounds such as nitrates, nitrites and sulfates -presence of bacteria -presence of radioactive contaminants |
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Purpose of goat industry
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-take advantage of forage to produce products
-meat industry is largest segment -angora sector is shrinking -dairy goat sector-300,000, few large scale operations -demand for synthetic fiber production is decreasing, demand for goat milk is increasing, as well as goat meat |
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Goat terminology
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-doe: female goat that has kidded
-doeling: female goat that hasn't kidded -buck: intact male -wether: castrated male -kid: offspring |
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Demand for goat meat
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-Has increase because:
lower in calories, fat, saturate fat and cholesterol than chicken beef, pork and lamb, and just as high in protein |
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Doe: lactation
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-negative energy balance at kidding, not eating enough to meet energy requirements, mobilizing fat
-can produce milk for 305 days or more; DMI is 4-7% of BW, cow DMI is 3-4% of BW -rations are typically same as dairy cow rations -meat goats and angora goats are dried off at weaning of kids (4-7 wks) -goat milk very similar to cow milk, fat is a little higher, lactose a little less |
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Doe: anestrous
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-goats are seasonal breeders
-should be fed maintenance diet during this period unless they are lactating |
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Doe: flushing/breeding
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-increasing nutrient intake (energy and some protein) at time of breeding to increase ovulation rate, and lambing rate.
-flushing thin does has been shown to improve breeding performance -2 to 3 weeks before and 1 week during breeding, increases ovulation rate |
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Doe: early/mid gestation
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-gestation is 146-150 days
-will be milking for first 90 days of gestation if given 60 day dry period -BCS of 3.5 for parturition, feed concentrate during dry period to meet this, may also need to be fed during second half of dry period to prevent ketosis (pregnancy toxicity) |
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Doe: late gestation
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-doe will mobilize body fat to meet nutrient requirements if energy intake is inadequate
-excessive use of body fat results in ketosis (pregnancy toxemia) -ketosis is most likely to occur during late gestation (in cows it is in early lactation) |
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Goat kid nutrition
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-Colostrum within 12 hours of birth, feed 10% body weight, at least half this should be ingested within 2 hours. Goats have synepithelialchorial placenta, so IgG can't pass through to fetus
-liquid feeding stage; can feed goat milk, cow milk or milk replacer -can begin weaning after 3 days, fully weaned at 4 weeks -should be fed highest quality forage -feed .3 lbs of high quality starter |
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Rate of passage
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-goats and seep have a faster rate of passage compared with cows
-feeds are therefore digested less by goats -compared to cows, goats and sheep have higher DMI relative to body weight |
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Selective feeding behavior
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-goats consume plants otherwise avoided by cows and sheep, they are browsers
-goats are a great complimentary species for other ruminants on pasture -this selective behavior also enables the goat grazing on pasture with higher level of plant diversity |
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Hair fiber production
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-coarse guard hair and cashmere (fine undercoat) produced by meat goats
-mohair produced by angora goats -both cashmere and mohair have market value -metabolizable energy for mohair production-33% efficient. sulfur containing AA are signifiant components of mohair, so sulfur intake is critical--methionine and cysteine are sulfur AA |
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Activity levels
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-minimal activity: stable feeding conditions
-low activity: intensive management and tropical range, metabolizable energy 25% greater than minimal activity -medium activity: semiarid rangeland and slightly hilly pasture, ME 50% greater than minimal activity -high activity: arid rangeland, sparse vegetation and mountainous pasture, ME 75% greater than minimal activity |
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Factors affecting milk flavors
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-some feeds cause off flavors in milk: turnips, onions, garlic, cloves, peppermint
-caused by essential oils: aroma compounds in feeds, can be a source of energy or waste product of the plant, act as attractants for insects and anti-bacterial agents |
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Things to consider when feeding goats
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-Urinary calculi
-poisonous plants -bloat -acidosis -prussic acid poisoning -nitrate poisoning -milk fever -tall fescue toxicosis -enterotoxemia -white muscle disease |
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Dairy industry
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-number of farms has decreased, there are mostly large operations. But the number of cows per farm has increased, and the production per cow has dramatically increased due to improvements in nutrition
-stable increase in milk production in the US -number of organic operations has increased because the amount of certified organic farmland |
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Fresh cows
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-have recently transitioned from pregnancy to the process of parturition and on to lactation
-health and productivity of a fresh cow is dependent on the success of this transition -period of time from last 3 weeks of dry period to the first 3 weeks of lactation is the transition or periparturient period -transition cows are changing from the hormonal and metabolic status characteristics of the non-lactating (dry) cow to the hormonal and metabolic status of the lactating cow -usually managed to maintain a 12 month calving interval, so cows must be pregnant within 80 days of calving because gestation length is 282 days -80 days postpartum corresponds to period of time when cow is peaking in milk production and continues to run on an energy deficit -cow's ovaries will remain inactive until energy balance progresses beyond its most negative balance and is returning toward balance -feeding and management that leads to increased DMI will always lead to increased productivity and profits -DMI is limited by time feed spends in digestive tract so it can potentially be increased if the rate of removal from the rumen is increased |
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Fresh cow problems
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-ketosis
-fatty liver -displaced abomasum -retained placenta -mastitis -metritis -milk fever -acidosis |
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Energy status during lactation
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-energy intake does not meet energy requirements for the first 100 days of lactation, which is why the cow loses BC. After this, her energy intake will become greater, until her dry off day (~305) when she will be back to a 3.5 BCS
-her peak production also doesn't coincide with her peak DMI |
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Removal of feed from rumen
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-feed may be colonized and fermented by rumen microbes
-microbial activity may process a portion of the feed into gases, which are eructed -microbial activity may turn feed material into valuable compounds (VFAs) that are absorbed through the rumen wall -feed material may be reduced in size to small and dense particles that pass out of the reticulum and rumen into the omasum |
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Diet high in coarse forage vs grain
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-processed slowly and accumulate in the rumen
-as coarse forage is replaced by grain, rate of feed removal increases allowing DMI to increase -however, a decreased amount of saliva is produced because less chewing is required -at the same time, increased amounts of acid are being produced as microbes ferment grain -this can lead to acidosis---laminitis |
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Cows: mid-lactation to late lactation
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-lactating cows should be fed a diet that matches their production potential (high vs low diets)
-in general, a nutrient deficiency during lactation will result in reduced milk production -both deficiencies and excesses will have a negative impact on farm profitability -developing groups, rations for each group and moving animals into groups at appropriate times helps to meet the nutritional requirements for lactating cows as they progress through lactation |
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Time budget
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-3-5 hours eating
-10-12 hours lying down and resting -7-10 hours ruminating -30 minutes drinking -2-3 hours in milking parlor *these times vary depending on environmental factors, as well stage in lactation |
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Dry cow program
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-provide proper nutrition for fetal development
-preparing digestive system for upcoming lactation -retooling their metabolism for the challenges of lactation -maintaining the proper body condition |
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Shortened dry period
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-there is a lot of data that supports a 60 day dry period to maximize milk yield the next lactation
-some experiments showed that a 30 day dry period is possible without sacrificing milk production the next lactation -possible advantages of reducing dry period: increased income from milk production, simplified dry cow management, decreased metabolic disorders, and alleviation of overcrowded dry cow facilities |
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Essential oils
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-essential oils are blends of secondary metabolites obtained from the plant volatile fraction by stem distillation
-provide specific flavors and odors to many plants -two important active chemical groups: terpenoids and phenylpropanoids -have a wide variety of effects on health, including positive effects on: cardiovascular disease, some tumors, inflammatory processes, and diseases in which uncontrolled proliferation of free radical is very damaging -most important activities of these compounds are of antiseptics and antimicrobials |
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Nitrogen efficiency
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-N intake--30-40% fecal N, 35-45% urinary N, 25-35% milk N
-precision feeding: balanced energy and RDP supply, reduces fecal and urinary N and increase milk N |
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Am vs PM cut alfalfa baleage
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-PM cut increased total Nonstructural CHOs, increased DMI, milk yield, milk protein and fat, omasal flow of microbial protein and bacteria captured more NH3.
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Ketosis
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-most animals evolved in an energy-scarce environment, thus milk made by mammals is rich in energy
-cows acquire the energy to make this high-energy product from 2 sources: feed energy and stored body fat -energetic efficiency is higher when milk is produced using feed energy rather than the energy stored in body fat -cows should be managed to maximize DMI to be more energetically efficient to avoid ketosis -body fat is a good source of energy but it isn't a versatile source -body fat is effectively used to make milk fat, but poorly used to meet the cow's other energy needs -although a significant portion of the energy cost of making milk comes from fat production, there are other energy cost involved in milk production that are met through glucose -most of the glucose needed by the ruminant is produced by the animal during gluconeogenesis, which occurs mainly in the liver -because glucoe is sued to make lactose (milk sugar) and because lactose content in milk is relatively constant, a deficiency of lactose will result in a reduction in milk production -glucose is made from substances called glucogeneic precursors |
-cows in an energy deficit are mobilizing body fat to help meet the body's energy needs-as evidence of this fact, blood samples from transition cows in negative energy balance show high levels of circulating NEFAs (non-esterfied fatty acids)
-in order to use body fat as an energy source, lypolysis must occur during which the ester bonds of TAGs in fat tissue are broken -this releases glycerol and NEFA into the blood in a 1:3 proportion -the liver takes up NEFA in proportion to its level in blood -TAGs remain in the liver until they can be oxidized in liver cell mitochondria or repackaged for export -because the export process is slow relative to the import of NEFA, TAGs may accumulate in the liver leading to fatty liver -oxidation of liver TAGs involves degrading TAGs back to NEFA and sending them to the TCA cycle -in order for NEFA to be completely oxidized in the TCA cycle, glucogeneic precursors must be available. If they are in short supply, NEFAs will be incompletely oxidized, which will cause the production of ketones -cow in negative energy balance, DMI doesn't keep up, so she will mobilize fat, which will produce NEFAs, some of which can be used for energy, but if too much can cause fatty liver or ketosis |
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Strategies to meet glucose demands and decrease NEFA supply
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-propylene glycol and calcium propionate are both sources of glucogenic precursors
-niacin is involved in energy metabolism and reduces blood NEFA -Choline improves efficiency of gluconeogenesis in the liver, decreases NEFA, less TAGs in liver, reduced fatty liver -monesin increases rumen production of propionate, a glucogenic precursor, improves propionate concentration which improves energy efficiency and DMI. Significantly helped with DA, ketosis and mastitis |
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NFC concentration in prepartum diet
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-increase in nonfiber CHOs (starches and sugars) increased prepartum DMI and prepartum insulin, which help with metabolic issues and glucose, respectively
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Lipid metabolism
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-Triglycerols and glycerols are hydrolyzed and FA are biohydrogenated in the rumen
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Milke fever
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-occurs when blood Ca levels fall below the level necessary to support normal physiology
-caused by reduced blood Ca levels, which also leads to poor muscle tone and this may predispose the cow to a DA, RP or mastitis -Ca homeostasis: PTH (stimulates Ca to be released from bone) and calcitonin (puts Ca back into bone) -usually occurs within 3 days of parturition -symptoms: cows stop eating and are unsteady on their feet, dull eye a dilated pupils, and cows will be unable to stand up |
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Three factors causing drop in blood Ca
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-the drain on blood Ca imposed by milk production
-the inability of the digestive system to deliver enough Ca to replace that which is used for lactation -the inability of the parathyroid gland to direct mobilization of stored Ca reserves |
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Controlling milk fever--Dietary cation-anion difference (DCAD)
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-by feeding more anions and thereby reducing DCAD for the 2 weeks prepartum, the cow is put into a calving-type condition
-she is forced to mobilize the cation that she has in storage, which means the parathyroid gland is forced to secrete PTH prior to parturition -the intake of Ca and K (cations) by dry cows should be restricted |
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Ruminal acidosis
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-generally applied to the condition in which the rumen contents drop in pH below 6.2
-two forms of acidosis: acute (pH falls below 5.7) and subacute (pH 5.7-6.2) -high grain or concentrate concentrations in diet cause the production of propionate, which causes acidosis. This can lead to laminitis, liver abscesses and milk fat depression |
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Systemic problems associated with acidosis
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-change in microbial activity leading to increased production of trans-fatty acids
-change in population of microorganisms inhabiting the rumen, increasing the number of those that decarboxylate the AA histidine to create histamine -ruminal concentration of histamine increases -the rumen wall becomes inflamed and histamine, along with bacteria, passes into the portal blood---cause laminitis |
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Calves and heifers
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-objective of calf raising program is to keep the calf alive, healthy and growing at a rate that she will be large enough to breed by 14 months of age
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colostrum
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-cow's have a synepithlialchorial placenta, which doesn't allow Igs to pass from the cow into the blood of the developing calf
-colostrum is high in IgG, so the calf must consume this asap -should received colostrum that is equivalent to 10% of the birth weight -colostrum should be fed for the first 3 days of life at a rate of 4 quarts per day -after that milk or milk replacer should be fed at a rate of 1 quart daily |
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Milk replacers
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-milk replacers from untreated soybean contain enzyme inhibitors and for some calve, allergens
-the enzyme inhibitors reduce protein digestion and retard growth in calves, and it is also somewhat deficient in methionine -antibiotics are sometime added to milk replacers to aid in growth and prevention of bacterial scours |
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Calf starter
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-When calf is 4 days old, a calf starter should be offered fresh daily along with clean, fresh water
-contains ionophores which help control the protozoan disease coccidiosis -high quality calf starter should be highly palatable and nutritionally balanced -feedstuffs often included in calf starters include cracked or flaked corn, oats, beet pulp, molasses, soybean meal and milk products -VFAs from the digestion of grain in calf starters stimulates early rumen development -by 8 weeks, calves should be eating 6 to 8 lbs of calf starter, calf now has a functional rumen and is capable of rumination -at this time, high quality forages should be introduced |
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Guidelines to wean a calf
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-should be at least four weeks old
-should be eating 1.5-2.0 lbs of calf starter daily -the above rate of calf starter consumption should have occurred for 3 consecutive days -the size and health of the calf should be considered |
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Prebred and postbred heifer
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-at this time, herd replacement calves should be changed to a heifer feeding program that will include forages
-heifer feeding program should include a ration balanced for all nutrients to support proper heifer growth and development -top quality hay is always desirable for young heifers -hay crop silage, corn or sorghum silage and pasture can all be used as well -heifers should be grouped according to nutritional need and body size -two weeks prior to calving, the heifer should be treated and fed differently -during the two weeks prior to freshening, cows should be fed up to a maximum of .5% of the body weight |
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