Factors Affecting Productive and Reproductive Performance of Dairy Cows in El Salvador

Abstract

Data from 19 herds in El Salvador, covering 1967 to 1972, were analyzed to determine factors affecting milk yield. Total data set was 2919 lactation records. Mean performance was 154 d open, 282 d in milk, and 2636kg milk; mean age of cows was 66 mo. Age of first calf heifers was 34.4 mo. Holstein and Brown Swiss crossbreds and pure Guernseys produced 2710, 2797, and 2737kg; Mestiza, Criollo and Brahman produced 2439, 2083, and 1974kg. Mean increases of yield per percent increase of Holstein or Brown Swiss breeding was 9.9kg. Slight decreases of age at first parturition with upgrading were detected. January through June was most favorable for parturition with mean milk yield 3.6% higher than remaining months; effects of month of parturition seemed greatest for Brahman, Criollo, and Mestiza and least for Brown Swiss. Effects of days open on yields were similar to estimates in the United States, although large for Brahman, Criollo, and Mestiza. Regressions of yield on kilogram concentrates fed and kilogram body weight, pooled within Holsteins and Brown Swiss, were 1.53 and 2.55kg. Under climate and management conditions of this population, continued upgrading to Holstein and Brown Swiss seemed warranted, as did utilization of feeding and management practices profitable in temperate dairy cattle and milk production areas.