Evaluation of Urea and Dried Whey in Diets of Cows During Early Lactation

<p>Previous research indicated that soluble nitrogen may be utilized more efficiently for rumen microbial production in diets containing dried whey. To further evaluate this, 33 Holstein, cows (30 multiparous and 3 primiparous) were fed one of three concentrate mixes containing all natural proteins (SBM). 1% urea (U), or 1% urea and 30% dried whey (UDW) from wk 3 through 16 postpartum. Urea replaced portions of the soybean meal in the SBM mix while dried whey replaced portions of the corn and soybean meal. Cows were fed total mixed rations consisting of 40% (dry matter basis) corn silage, 10% alfalfa hay, and 50% of respective concentrate mix. Diets were formulated to be isonitrogenous at 16% crude protein, but soluble nitrogen was formulated to be approximately 23, 30, and 42% of the total nitrogen for SBM, U, and UDW diets. Milk production and composition were adjusted by analysis of covariance using the second week milk production and composition as covariates. Milk yield was similar (33.8, 33.4, and 33.2 kg/day) for cows or cows fed SBM, U and UDW, respectively, indicating that diets high in soluble nitrogen can support milk production equal to that of natural protein supplemented rations. Production of 4% fat-corrected milk (29.9, 28.0 and 29.2 kg/day) was lower for cows fed U diet because of lower milk fat percentage (3.23, 2.94 and) was lower for cows fed U diet because of lower milk fat percentages (3.23, 2.94, and 3.23%). Milk protein percentages (3.10, 3.04, and 3.04%) and solids-not-fat percentages (8.74, 8.79, and 8.81%) were not affected by type of concentrate · fed. Milk solid percentages (12.02, 11.70, and 12.01%) and production of solids-corrected milk (30.3, 28.6, and 29.6 kg/day) were higher for cows fed SBM · and UDW versus U. Dry matter intakes · (22.0, 20.2, and 23.1 kg/day) were highest for cows fed UDW and lowest when fed U. Rumen parameters showed a decrease in molar percentages of acetate (56.6, 50.3, and 50.2%) for cows fed U, and UDW, but cows fed U had higher molar percentages of propionate (24.8, 28.6, and 25.0%). Molar percentages of butyrate were higher (13.6, 14.4, and 18.4%) for cows fed UDW. Ratios of acetate+butyrate: propionate were highest (2.95, 2.40, and 2.93) for cows fed SBM and UDW. Concentrations of rumen ammonia (11.8, 20.3 and 13.5 mg/dl) and serum urea (19.5, 22.9, and 16.5 mg/dl) were highest for cows fed U. In conclusion the utilization of urea nitrogen for milk production was improves by adding dried whey to simulate rumen microbial protein synthesis to diets of early lactation cows</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis - Open Access

Discipline thesis:degree_discipline

Dairy Science

Year dc:date.available

1985

Author dc:creator

• Casper, David Paul

Contributors dc:contributor

• David J. Schingoethe

• Dairy Science

Statement dc:rights

• <p>In Copyright - Non-Commercial Use Permitted<br /><a href="http://rightsstatements.org/vocab/InC-NC/1.0/">http://rightsstatements.org/vocab/InC-NC/1.0/</a></p>

Language dc:language

en

Repository record dc:identifier

https://openprairie.sdstate.edu/etd/1321

OAI identifier oai:identifier

oai:openprairie.sdstate.edu:etd-2322