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TAMU ANSC 318 - Dairy Cattle Nutrition and Feeding II
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ANSC 1st Edition Lecture 21 Outline of Last Lecture I. Dairy Cattle NE Requirements, Particle Size, and Adding Buffers to Diet. Outline of Current Lecture II. Adding Fat to Dairy Cow Dietsa. Benefitsb. SourcesIII. Feeding Systems for Lactating Dairy Cowsa. Traditional Feeding Systemi. Advantagesb. Total Mixed Ration Feeding Systemi. AdvantagesIV. Body Condition Scoring in Dairy Cowsa. Target BCS ScoresV. Nutritional Recommendationsa. Phase I – Early Lactationb. Phase II – Mid Lactationc. Phase III – Late LactationCurrent LectureDairy Cattle Nutrition and FeedingAdding Fat to Dairy Cow Diets•Energy density of the diet can be increased by replacing a portion of the grain in the diet with fat (fat is 2.5X more energy dense)•Fat-added diets allow more energy intake while avoiding excess-starch and low-fiber intakes•Including more than 8% fat in total diet will cause:-DMI to decrease-fiber digestion to decrease (too many LCFAs)-incidence of digestive upsets to increase•Most grains and forages contain about 3% fat•Therefore  fat can be added to diets at 5% without adversely affecting DMI or digestibility•3.5% milk fat is idealBenefits of Adding Fat•high-producing cows during the first 2-5 months of lactation benefit the most from fat-added dietsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.•cows fed fat-added diets typically produce 4 to 6 lbs more milk per day•cows fed fat-added diets lose less weight during early lactation•heat stressed (> 80 degrees) cows eat less and produce less milk-heat increment is much lower for fats•feeding fat-added diets to heat stressed cows is beneficial because heat increment is decreased•feeding fat-added diets may reduce the incidence of ketosis and enhance reproductive performance-more likely to return to estrus and rebreedSources of Fat for Lactating Dairy CowsFat Source Fat % CP % ADF % Amount to feed, lb/day1. Plant Oil Seed Sources:Cottonseed 23 23 35 5-7Soybean 19 41 6 5-7Canola 40 20 12 3-52. Unprocessed Fat Sources:Tallow 99 -- -- 1-1.5Hydrolyzed animal-vegetable oil blends99 -- -- 1-1.53. Processed Fat Sources:Ca salts of fatty acids85 -- -- 1-1.75Prilled Fat 99 -- -- 1-1.5•Can feed more than 7 pounds of soybeans if they are heated•Cottonseed is very common in TX•Unprocessed fat sources will be hydrolyzed in the stomach -negative effect on fiber fermentation•Processed fat sources  bypass fat-not hydrolyzed in rumen; go to the small intestine-most expensive fatFeeding Systems for Lactating Dairy CowsTraditional Feeding System:•Forages and concentrates are fed separately•Steps to a Traditional Feeding System-determine nutrient requirements (easy)-estimate forage DMI (difficult in grazing cows)-estimate forage nutritional quality (difficult; depends on stage of maturity)-challenging to formulate concentrate mix to supply nutrients beyond what the forage provides•Most challenging•No way to regulate what they eat when grazingAdvantages:-harvesting and chopping forages for TMR system is expensive-costs of grazing forages is cheap-cost of feeding equipment for this system is less expensiveTotal Mixed Ration (TMR) Feeding System•Forages and concentrates mixed and fed together•Steps to TMR feeding system-determine nutrient requirements (easy)-estimate forage DMI (easy since cows aren’t grazing)-estimate forage nutritional quality (easier for harvested forages)-formulate TMR (easy compared to formulating supplement for grazing cows)Advantages-cows aren’t permitted to eat only their “favorite” forage-cows are forced to eat the correct balance of forage and concentrate feeds-many small meals are eaten throughout the day  helps maintain stable rumen pH-easier to feed cows in various production groups-reduce the incidence of social dominance•Traditional causes greater changes in rumen pH -more likely to see decrease in milk fat synthesisBody Condition Scoring in Dairy Cows•Important management technique to gauge energy status of mature cows, as well as developing heifersFive-point boy condition score1.0 to 1.5 Severe under-condition2.0 to 2.5 Thin3.0 to 3.5 Moderate4.0 to 4.5 Fat5.0 Severe over-conditionBody Condition Score 2•Rump Area:-shallow cavity lined with fatty tissue at tailhead-some fatty tissue felt under pin bone-pelvis easily felt•Loin Area:-ends of short ribs feel rounded-upper surface felt with slight pressure-depression visible in loinBody Condition Score 3•Rump Area:-no visible cavity around tailhead-fatty tissue is easily felt over whole rump-skin appears smooth-pelvis is felt with slight pressure•Loin Area:-ends of short ribs can be felt with pressure-thick layer of tissue on top-only a slight depression in loinBody Condition Score 4•Rump Area:-folds of fatty tissue are visible around tailhead-patches of fat are present around the pin bones-pelvis is felt only with firm pressure•Loin Area:-short ribs cannot be felt even with firm pressure-no depression visible in loin between backbone and hip boneTarget of BCS for Dairy Cattle at Critical TimesTime of Scoring Target BCS Reasonable RangeCows:Calving 3.5 3.0 to 4.0Peak Milk 2.0 1.5 to 2.0Mid-lactation 2.5 2.0 to 2.5Dry off 3.5 3.0 to 3.5Heifers:6 months of age 2.5 2.0 to 3.0Breeding 2.5 2.0 to 3.0Calving 3.5 3.0 to 4.0Nutritional RecommendationsEarly Lactation – Phase IGoals to achieve during early lactation:•Maximize Intake  for every 1 lb increase in DMI, milk production will increase by 2.5 lb•Minimize Body Tissue Loss  Most dairy cows will have a negative energy balance during •1 lb of body tissue mobilized during early lactation will supply:-enough energy for 7 lb of milk-enough protein for 3.5 lb of milkFeeding Recommendations:•use high quality forages (i.e. alfalfa hay)•use palatable feeds with high energy density•ensure adequate effective fiber levels (min 20% ADF)•Consider adding fat to the diet (i.e. bypass fat or whole cottonseed)•use all natural protein supplements (no urea!)•consider use of high-quality bypass protein (UIP) sourcesEffects of Amount and Source of UIP on Milk ProductionFeedstuffs Low-UIP Diets High-UIP, low quality dietsHigh-UIP, high quality dietsCorn Silage 50 50 41.8Corn Grain 28.5 30.4 28Soybean Meal (6.4% lysine)18.3 9.4 11Corn Gluten Meal -- 7 --(1.7% lysine)Dried Brewers Grain (3.8% lysine)-- -- 16Milk Production, lb/day 68 70


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TAMU ANSC 318 - Dairy Cattle Nutrition and Feeding II

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