Abstract
Sample day observations of Guernseys, Holsteins, and Jerseys were evaluated to determine contributions to variation and relations among milk, fat, and protein yields; fat and protein percentages; and somatic cell score. Somatic cell scores and mean yields for sample days increased with parity, whereas fat and protein percentages decreased. Lactation curves were approximated, examined, and compared. Fat and protein yield decreased at different rates, and persistency of yields decreased with increasing parity. Among breeds, curves differed more for fat than protein yield. Estimates for fat percentage also differed more than for protein percentage among breeds and parities. Curves for protein percentage reached the nadir earlier in lactation than curves for fat percentage. Somatic cell scores were highest at the beginning of lactation for cows in first parity but were highest at the end of lactation for cows in later parities. Somatic cell scores increased more rapidly following the nadir for cows in later lactations. Effects of month and age of calving were estimated for all traits.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
