Evolución de peso de vaquillonas hijas de vacas cruza y puras sometidas a niveles de oferta de forraje en gestación y lactancia

The objective was to study how high and low OF during breeding and crossing in the mother affected the evolution of PV of heifers during breeding. The experiment was carried out at the Bernardo Rosengurtt Experimental Station between May and November 2022. 30 heifers from an experiment in which their mothers were subjected to a factorial design of treatments of High and Low OF (8 and 6 kg M.S. / kg P.V. respectively) and genetic group of the cows (Angus, Hereford, AA x HH and HH x AA); born in the spring of 2021 (average birth date 13-09-2021 ± 93 days). The experimental design employed was a completely random design, where the experimental unit was each animal. The average weaning date was 25/02/2022 ± 8 days, with an average weight of 196 ± 12 kg. The PV of the animals was measured monthly from the beginning of the experiment until the end of it (March - November). The OF values were different depending on the season and the average annual OF was 1.7%. The PV of heifers was affected by the month, while it was not affected by the OF, genotype or interactions OF x Month and Genotype x Month. In the month of May, the weight was 207 ± 8 kg, in that period (May - June), the evolution of PV had a period of stability (P > 0.05), while in July the PV begins to increase but does not differ statistically from June, reaching a PV of 221 ± 8 kg. From August to November, the evolution of cow weight increases (P < 0.05), achieving a PV of 279 ± 8 kg in November. The weight gains of heifers tended to be affected by the Month effect, while they were not affected by OF, neither the Genotype, nor the Genotype x Month and OF x Month interaction. In the month of May, the heifers obtained an average daily gain of 0.150 ± 0.07 kg/day. In the month of June, the heifers obtained daily weight losses of - 0.174 ± 0.07 kg. In the months of July to November, they experienced weight gains, where the highest daily gains were in the months of July, August and November being of 0.64 ± 0.07 kg, 0.62 ± 0.08 kg and 0.53 ± 0.07 kg respectively (P<0.05). In the months of September and October, there is a decrease in daily earnings compared to the previous months of July and August (P<0.05), where the lowest levels of earnings are evident in the month of September being 0.23 ± 0.08 kg, while in October 0.34 ± 0.07 kg.