Reproductive efficiency of Nellore cows nursing Nellore or crossbred Simmental × Nellore calves
Vargas Junior, Fernando Miranda de, Wechsler, Francisco Stefano, Oliveira, Marcus Vinicius Morais de, Seno, Leonardo de Oliveira, Fernandes, Alexandre Rodrigo Mendes, Camilo, Fernando Rossi
R. Bras. Zootec.
DATA DE PUBLICAÇÃO
The objective of this study was to analyze the influence of genetic group (GG) of the calf during gestation, mobilization of body reserves and period of postpartum anestrus in Nellore cows. Thirty-seven primiparous and multiparous cows were used: 24 gave birth to Nellore (NEL), and 13 gave birth to ½ Simmental × ½ Nellore (SIM) calves. According to the date of calving, cows were divided into three blocks, with intervals of 20 days between blocks. The body condition (BC) of the cows was estimated subjectively on a scale from 0 to 5 points, with intermediate grading of 0.5 points. We measured the thickness of subcutaneous fat (SF) between the 12th and 13th ribs and rump by ultrasound. Blood samples from each cow were collected weekly from the third week after birth until weaning, to analyze the level of progesterone; in the samples collected until 16 weeks postpartum, we analyzed the concentration of nonesterified fatty acids (NEFA). The gestation period of mothers of NEL calves was eight days longer, on average. The variables relating to the mobilization of body reserves (NEFA, BC and SF) were not influenced by calf GG, with the only significant effects being the number of days postpartum, with a peak in the concentration of NEFA between the sixth and eighth weeks and linear decrease in BC and NF. Mothers of NEL calves remained in anestrus for 4.6 weeks longer than the mothers of crossbred calves.
- Voluntary intake of dry matter and performance of Nellore cows and their Nellore and crossbred Simental × Nellore calves
- Protein requirements for females of Nellore, Nellore × Angus and Nellore × Simmental fed on two forage: concentrate ratios
- Energy nutritional requirements for females of Nellore, Nellore × Angus and Nellore × Simmental fed on two forage: concentrate ratios
- Carcass traits of Nellore, F1 Simmental × Nellore and F1 Angus × Nellore steers fed at maintenance or ad libitum with two concentrate levels in the diet
- Intake, digestibility and nitrogen use efficiency in crossbred F1 Holstein × Zebu grazing cows