Variations in the Temperature-Humidity Index and Dorsal Fat Thickness during the Last Trimester of Gestation and Early Postpartum Period Affect Fertility of Bos indicus Cows in the Tropics

Effects of Season on Donor and Recipient Cows and Calf Performance from Birth to Weaning in Embryo Transfer Programs in the Tropics

Simple Summary

It is well-known that embryo transfer is a powerful tool which can increase the number of offspring of donor cows, thus improving cattle efficiency. The recipient dams are vital in a successful embryo transfer program, as they will sustain the length of the pregnancy and directly impact the development of the embryo and the productive performance of the animal after birth. Evaluating the effect of season on donors, recipients and delivered offspring from a private farm, we found that the seasonal effect is more apparent in donor and calf performance than in the recipients. It seems to be that the performance of the calves measured by birth and weaning weight favors the embryo-transferred offspring. However, there is a bias towards measuring the performance of calves born by embryo transfer as their condition was favorable compared to calves born by natural mating, as the latter calved at pasture without supervision, whereas the former the recipient dams calved in selected pastures.

Abstract

The aim of this study was to assess the seasonal effect of an embryo transfer program in the tropics on the donor response, recipient reproductive performance and calf growth from birth to weaning. This study included five-year records from 145 donors, 1149 embryo transfers (ET) and 609 in calves. The effect of the season (dry or wet) was evaluated at the time of embryo flushing, embryo transfer and birth of the calves. There was a seasonal effect on the yield and quality of the embryos. The number of nonfertilized and transferable good quality embryos increased in the wet season. For the recipients, the probability of pregnancy after an ET decreased by 6% for each year of the dam’s age. However, no seasonal effect was found when comparing ET calves with their control group (natural mating—NM), nevertheless, weaning weight was associated with birth body weight, treatment, sex of the calf, season at birth, year of treatment, and dam’s age. Calves born by NM had lower average daily gain (ADG), and male calves registered higher gains than females. Likewise, calves born during the rainy season had lower ADG compared with calves born during the dry season. In conclusion, this study shows that seasonal effect is more apparent in donor and calf performance than in the recipients.

The Effect of Maternal Behavior around Calving on Reproduction and Wellbeing of Zebu Type Cows and Calves

The behaviors associated with domestic cattle such as maternal care are quite similar to those behaviors observed in wild ungulates. These behaviors allow the cow to bond with her calf, protect and provide it with nourishment and ultimately reduce the bond at weaning. Although maternal behavior is an important factor influencing the survival and early development of the newborn calf, Zebu type cows around calving have not been studied extensively. Herein, we consider the four main aspects of maternal behavior in cattle and particularly Bos indicus cows and calves. Firstly, we provide a brief description of the behavior of cows around parturition and the behavior of the first stages of the calves' lives. In the second part, the protective behavior of the mother is analyzed. Subsequently, examples of animal welfare implications followed by an analysis of some factors that affect calf survival, including mother experience and weather conditions, are discussed, and in the last part, reproduction along with some peculiarities of reproductive behavior, and the wellbeing of mother and calves are examined. We concluded that knowledge of maternal behavior of Zebu type cows around calving and interactions with calves might contribute to an enhanced reproductive efficiency of the mother and the welfare of the calf.

Effects of Separation of Cows and Calves on Reproductive Performance and Animal Welfare in Tropical Beef Cattle

Nursing a calf suppresses postpartum ovarian activity prolonging the period of anestrus. Diverse methods are used to reduce the effect of suckling; the most popular, restricted suckling, reduces the number of encounters mother-calf. Temporal weaning of the calf for periods of 24 h, 48 h, or even 72 h also suppress the effect of suckling and is commonly applied to cow-calf operations in the tropics. Early weaning of the calf, usually three to five months after birth, is a practice gaining popularity over the traditional system of weaning at seven months. Furthermore, the use of nose-flaps in the calf to avoid suckling is a common procedure in South America. Finally, weaning during the first week after calving is an established method to reduce postpartum anestrus. The objective of the present review is to discuss the effects of these methods on the reproductive performance of beef cattle and their animal welfare implications.