Influence of fetal sex on the productive performance of primiparous and multiparous dairy cows in a livestock farm in the department of Sonsonate, El Salvador

Abstract

The influence of fetal sex on the productive parameters of primiparous and multiparous cows in a herd of the dairy basin of the Sonsonate department of El Salvador was evaluated. The records of pure Holstein breed cows that calved between 2004 and 2017 were analyzed. A database was created in the VAMPP Bovino 3.0® software by collecting physical and digital records provided by the herd, such as the identification of the animal, calving dates, drying date, calving number, calf sex and biweekly milk production. From the base a total of 3,492 data belonging to 190 animals were extracted, with them the parameters to measure the productive performance of the animals under study were calculated. The independent variables evaluated were: parity (1st, 2nd and 3rd calving) and the fetal sex of the calf (Female and Male). The dependent variables were: average daily production per cow, production at peak lactation, days at peak lactation, duration of lactation per cow, total production at 305 days and persistence. For the statistical analysis, a completely randomized design with a bifactorial arrangement was applied, since the first 3 lactations and both sexes of the offspring were evaluated and the statistical test of Multivariate Analysis of Variance was also applied. The general averages of the variables analyzed were not influenced by fetal sex (p>0.05). However, there were statistical significance for all the productive variables and their interaction with the number of lactations, since the higher the number of deliveries, the average daily production, production at the peak of lactation and the cumulative production at 305 days increased. Primiparous cows took more days to reach peak lactation than multiparous cows and had the shortest duration of lactation compared to multiparous cows (p = 0.0001). Although the multiparous cows achieved higher milk production, they were not able to sustain it throughout the lactation period, presenting a lower percentage of persistence (multiparous = 90.52%; primiparous = 93.65%). When performing the multivariate test, it was found that the cows that in their three lactations produced female, female and male calves (HHM) had: the lowest productive yields, the shortest lactation duration and the least persistence, reaching the peak of lactation in a shorter period (p = 0.0007).