Document Type

Dissertation - University Access Only

Award Date

2012

Degree Name

Doctor of Philosophy (PhD)

Department / School

Dairy and Food Science

First Advisor

Kenneth Kalscheur

Abstract

Two studies were conducted to determine the effects on growth, nutrient
utilization, metabolic profile , and long-term performance of feeding rations with high
inclusion rates of distillers grains to dairy heifers. The first study evaluated ensiling
distillers wet grains with solubles (DWGS) with com stalks (CS) with or without a
silage additive, as feed for heifers . Ensiling characteristics (pH, acetic acid, lactic acid , and amrnonia-N) and nutrient composition (dry matter, crude protein , fiber, and ash) of the blends were not affected by the silage additive. In a feeding trial with 12 heifers,
feeding the ensiled blends maintained body weight gain, skeletal frame growth,
de creased dry matter intake, and improved the gain to feed ratio compared to a control diet. The silage additive increased total tract nutrient digestibility of the blend when fed to dairy heifers. The second study determined if increased dietary fat from feeding distillers dried grains with solubles (DOGS) affected growth, metabolism , or long-term performance of dairy heifers. Thirty-three Holstein heifers ( 133 ± I 8 d old) were us ed in a 24-wk randomi zed complete block design feeding trial with three treatments . Treatment diets were : I) a control diet containing com and soybean products (C) , 2) a low-fat diet containing reduced-fat distillers dried grains and com (LFDG) and 3) a hi g h- fat diet containing traditional high-fat distillers dried grains with solubles (HFDG). All diets contained approximately 40% hay, 25% com silage, and 35% concentrate mix (DM basis). Diets were balanced to be isonitrogenous and isocaloric, but not isolipidic. The HFDG diet was formulated to contain 4.8% fat compared to 2.8% in the C and LFDG diets, which had more starch. Body measurements and blood samples for metabolite and hormone analysis were taken throughout the trial. Post-feeding period, data were collected on heifer reproduction and lactation performance. Growth performances were similar among treatments. Total tract digestion of dry matter and organic matter were similar among treatments, but crude protein and fiber digestion were greater in heifers fed the HFDG diet compared to the LFDG and C diets. Analysis of blood metabolites and metabolic hormones indicated metabolic energy status of the heifers was similar among treatments. However, plasma cholesterol increased in heifers fed the HFDG diet compared to the other diets. Progesterone analysis indicated that heifers fed the HFDG diet were pubertal at smaller body weights than heifers fed the LFDG or C diets. Data collected post trial demonstrated that heifers fed LFDG or HFDG were similar to heifers fed C for number of AI services, age at conception, and age at first calving. However, heifers fed HFDG tended to require fewer AI services per conception compared to heifers fed LFDG. Milk yields and components during the first 100 days in milk were similar for heifers fed HFDG compared to C. Heifers fed LFDG had greater milk production and tended to have increased milk protein yields compared to heifers fed the C diet. Based on these results, growing pre-pubertal heifers can be fed dietary fat from DOGS in replacement of starch from com and maintain growth performance, nutrient utilization, or future reproductive or lactation performance.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds
Heifers -- Feeding and feeds
Distillers feeds

Publisher

South Dakota State University

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Rights Statement

In Copyright