Paper-Lecture43 - Effects of Fat Saturation and Source of...

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Effects of Fat Saturation and Source of Fiber on of Nutrient Digestion and Milk Production by Lactating Dairy Cowsl92 J. PANTOJA, J. L. FIRKINS,, M. L. ABSTRACT Six primiparous cannulated cows were assigned to six treatments in a 6 x 6 Latin square design to evaluate the effects of degree of fat saturation and amount and source of effective fiber on site of nutrient digestion and milk production. Cows were fed for ad libi- tum intake a control diet with no added fat or diets with 5% added fat from saturated tallow, tallow, or animal- vegetable fat; the diets with animal- vegetable fat had 40% forage, 40% for- age plus 20% soyhulls, or 60% forage. Ruminal acetate:propionate was higher when soyhulls replaced forage NDF be- cause of the higher digestibility of soy- hulls in the rumen and total tract. Rumi- nal digestion of NDF was decreased as unsaturation of fat increased. True and apparent efficiencies of bacterial protein synthesis were increased as fat unsatura- tion increased, probably because of reduced recycling of microbial N in the rumen. The digestibility of fatty acids in the small intestine was higher in cows fed no fat than in those fed fat and was reduced as fat unsaturation decreased, primarily because of the saturated tallow. Dry matter intake was decreased 14% by increased fat unsaturation. All fat supple- ments depressed milk protein percentage. Received October 29, 1993. Accepted February 25, 1994. 'Salaries and research support provided by state and federal funds appropriated to the Ohio Agncultd Re- search and Development Center, The Ohio State Univer- sity. Contributing to Regional Research Project NC-185. Journal Article Number 221-93. 2Supported in part by the Ohio Dairy Farmers Federa- tion Milk Check-Off Program, Columbus. 3Reprint quests: Plumb Hall, 2027 Coffey Road. 4Department of Veterinary Clinical Sciences. Site EASTRIDGE, and B. L. HULL4 Department of Dairy Science The State University Columbus 43210 Production of 4% FCM tended to de- crease linearly as unsaturation of fat in- creased. In diets with added fat, a degree of saturation between saturated tallow and tallow (iodine values of 18 and 62) appears to be optimum for fatty acid digestibility and DMI. wey words: fat saturation, effective fi- ber, fatty acid digestibility, milk produc- tion) Abbreviation key: AVF = animal-vegetable fat, C = control, FA = fatty acid, HF = high forage, IV = iodine value, LCFA = long-chain fatty acid, LF = low forage, NANBN = non- NH3 nonbacterial N, SH = soyhulls, ST = saturated tallow, T = tallow. INTRODUCTION High producing dairy cows require high energy diets for maximal milk production in early and midlactation and to replenish body stores in mid to late lactation. The inclusion of fats in diets to increase energy density has became a common practice. Fats have the potential to improve the efficiency of energy utilization by converting preformed fatty acids (FA) to milk fat without the heat loss as- sociated with the conversion of carbohydrates to FA (3).
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This note was uploaded on 09/19/2011 for the course ANS 5446 taught by Professor Brown during the Spring '08 term at University of Florida.

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Paper-Lecture43 - Effects of Fat Saturation and Source of...

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