Changes on offspring/dam relationship, for improving reproductive performance in Gir and Holstein X Zebu dairy cows

Abstract

Postpartum anestrous and fertility of dairy cows are influenced by physiological processes of lactation and suckling. In the Triângulo Mineiro and Alto Paranaiba regions were tested three modifications of traditional management in milking Gir herds and crossbred herds. In the first one, the postpartum interval to first estrus of Girolando (Holstein x Gir) cows was equal to 122 ± 56.4 days (n= 8) under conventional management (two daily periods of milking and suckling); this interval was significatively shortened (70.6 ± 19.6 days; n= 9) when supressed milking and suckling in the afternoon, of alternated days, from the sixth day of lactation forward. The second modification were tested in Hostein X Zebu crossbred females, that were inseminated during the second postpartum estrus, verifying fecundation of 88.9% and service period of 157.8 days when in the interval between the fist and second estrus cows remained together with the calf, after milking made at morning, until the evening (n= 10); fecundation of 70.0% and service period of 161.3 days, when cows were non-milked nor sucled in the afternoon (n= 10); and fecundation of 50.0% and service period of 205.5 days, when cows were milked and suckled, twice a day (n= 9). The third modification were made in Gir and Girolando females that showed previously at least one behavioral estrus, suppressing milking and suckling periods in the afternoon, during first (T1) or second (T3) week of the estrous cycle. In the last day of these unique milking period, in all animals was injected one subdose of synthetic prostaglandin. In the respective control groups, milking and suckling were maintained, twice a day, and injected prostaglandin in the same way of experimental treatments (T2, T4). In these groups (T1, T3, T2 and T4), the incidence of synchronized estrus was equal to 75% (n= 12), 67% (n= 6), 40% (n=5) and 40% (n= 5), and the interval from prostaglandin aplication to synchronized estrus, 4.4, 2.0, 5.5 and 4.5 days, respectively. In the three experiments, data about cows weight , corporal condition, production levels and mamitis, were evaluated. The incidence of mamitis were higher in one group of cows that were, temporarily, not milked during afternoon, in advanced periods of lactation. It was concluded that these alternative practices of management may be useful for reproductive performance, but it is necessary to verify, previously, sanitary problems and time of usage.