Abstract
This study inferred genetic and permanent environmental variation of milk yield in Tropical Milking Criollo cattle and compared 5 random regression test-day models using Wilmink's function and Legendre polynomials. Data consisted of 15,377 test-day records from 467 Tropical Milking Criollo cows that calved between 1974 and 2006 in the tropical lowlands of the Gulf Coast of Mexico and in southern Nicaragua. Estimated heritabilities of test-day milk yields ranged from 0.18 to 0.45, and repeatabilities ranged from 0.35 to 0.68 for the period spanning from 6 to 400 d in milk. Genetic correlation between days in milk 10 and 400 was around 0.50 but greater than 0.90 for most pairs of test days. The model that used first-order Legendre polynomials for additive genetic effects and second-order Legendre polynomials for permanent environmental effects gave the smallest residual variance and was also favored by the Akaike information criterion and likelihood ratio tests.
Highlights
The quest toward increasing dairy productivity in tropical Latin America has refocused attention on the Tropical Milking Criollo (TMC) cattle (de Alba and Kennedy, 1994; Rosendo-Ponce and Becerril-Pérez, 2002)
A common practice in TMC is to continue to milk the cow beyond 305 d, because small amounts of milk per cow are still valuable in the tropical dairy unit
The declining pattern at the end of lactation detected by Van Vleck and Henderson (1961) was different from what we have found in TMC cattle
Summary
The quest toward increasing dairy productivity in tropical Latin America has refocused attention on the Tropical Milking Criollo (TMC) cattle (de Alba and Kennedy, 1994; Rosendo-Ponce and Becerril-Pérez, 2002). The TMC breed has greater fertility, survival rate, and longevity than other adapted breeds (Bodisco et al, 1968; Rosendo-Ponce and Becerril-Pérez, 2002), and its milk is high in fat, proteins, and total solids These cattle have been under selection for total milk production since the 70s. Studies of lactations under hot tropical conditions are very scarce, especially with local breeds Proper husbandry of these cattle requires consideration of genetic and environmental factors, and characterization of lactation is an important issue. Mathematical functions developed for cows adapted to temperate regions are fitted to data from tropical cows (Osorio-Arce and Segura-Correa, 2005)
Sign-in/Register to view highlights & summary 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.
