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Document Type

Thesis - University Access Only

Award Date

2012

Degree Name

Master of Science (MS)

Department

Dairy Science

First Advisor

Kenneth Kalschuer

Abstract

The objective of this study was to examine the effects of replacing com and soybean meal with field peas (Pisum sativum L.) in lactating dairy cow diets on milk production, dry matter intake and ruminal characteristics. The experiment used 16 lactating Holstein dairy cows (nine primiparous and seven multiparous) in a 4 x 4 Latin square design with 28 d periods. Cows were blocked into squares by parity, current milk production, and DIM, where one square consisted of 4 ruminally canulated cows (three multiparous and one primiparous). Cows averaged 122±47 DIM, 35.4±6.7 kg/d of milk, and weighed 645±82 kg at start of the experiment. Treatment diets were formulated to contain 17% crude protein, 32% neutral detergent fiber, 21 % acid detergent fiber, and 5% ether extract for a cow producing 43 kg/d of milk with 3.70% fat and 3.00% protein. All diets contained 37.6% com silage, 12.6% alfalfa hay, and 49.8% concentrate with com and soybean meal being replaced by peas at 0 (FPO), 12 (FP12), 24 (FP24) and 36% (FP36) (DM basis) inclusion in the diet. No changes in body weight or body condition score were observed. With increasing inclusion rate of peas in the diet dry matter intake, milk yield, milk protein percent, milk fat yield, milk protein yield, and energy-corrected milk linearly (P < 0.05) decreased, while milk urea nitrogen increased linearly. Feed efficiency responded quadratically to increased inclusion of peas. In the milk, total antioxidant capacity tended (P= 0.06) to linearly increase with the inclusion of peas. On an as-is fed basis, milk true protein, casein, and whey protein decreased linearly with the inclusion of peas. Rumen pH had a quadratic response to increasing inclusion of peas while rumen ammonia-N had a cubic response. Total volatile fatty acid had a quadratic response with FP24 being the greatest. Propionate and butyrate had cubic responses to increasing inclusion of FP. Acetate, valerate, iso-valerate, and acetate to propionate ratio all had cubic responses to increasing pea inclusion. !so-butyrate had a quadratic response. The predicted DMI for NRC was about 2 kg greater (24.2 vs. 22.1 kg/d) than for AMTS across all diets with the actual DMI being 23 .6 kg/d. Both the NRC and AMTS had diet CP increasing from 16.5 to 17.3% as FP inclusion increased, similar to the actual CP of the diets fed during the experiment. Both NRC and AMTS had diet RDP increasing as FP inclusion increased, but with NRC at an increasing rate. The NRC model increased (P < 0.001) from 9.9 to 13.2% while AMTS increased from 9.2 to 10.3% DM basis. In conclusion, the results of this experiment demonstrated that replacing com and soybean meal with increasing inclusion of field peas linearly decreased milk production and milk composition. Because the rumen protein degradability of field peas is greater than soybean, protein utilization of diets with increasing concentrations of FP was reduced resulting in lower milk production and milk protein percent.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds
Proteins in animal nutrition
Peas
Lactation
Milk yield
Tumor necrosis factor

Description

Includes bibliographical references (pages 53-60)

Format

application/pdf

Number of Pages

72

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

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