Development and reproductive performance of Hereford heifers of different frame sizes up to mating at 14-15 months of age

Arq. Bras. Med. Vet. Zootec.

Lobato

Restle

et al. 2020

The objective of this study was to evaluate, for two years, the performance of 124 female and 105 male Braford calves born during the first and second halves of the same calving season and the effects of birth period on the development of males until slaughter, as yearlings, and of females until calving, after having mated at 13-15 months of age. Early-born females were heavier than those born late at weaning (119.3 vs 109.9kg; P<0.05), at the start of the breeding season (275.0 vs 263.0kg; P<0.05), and at the end of the breeding season (300.0 vs 289.5kg; P<0.05), in addition to being more fertile (70 vs 50% pregnancy rate). There was no difference (P>0.05) in the development of males born early in relation to those born late, except for weaning weight, which was higher in the former. Steers born early were ready for slaughter at a younger age (459.6 vs 490.1 days; P<0.05), and both groups (early- and late-born) had a body condition classified as fat (4.21 points). In intensive production systems, both male and female calves perform better if they are born during the first half of the calving season.

Section: Discussionmentioning

confidence: 87%

Performance of calves born in different periods of the calving season in intensive beef cattle farming

Arq. Bras. Med. Vet. Zootec.

Lobato

Restle

et al. 2020

“…There was no difference in pregnancy rate between the BMI classes (Table 2). M. D. Silva, Lobato, Vaz, Eloy and Vaz (2018) evaluated different ratios of weight (kg) to hip height (cm) in Hereford heifers mated at 14-15 months of age and also found no differences in pregnancy rate. However, in the present experiment, all groups had reached the minimum weight recommended for their mating age.…”

Section: Resultsmentioning

confidence: 99%

Body mass index at calving on performance and efficiency of Zebu cow herds

Cerdótes

Pacheco

et al. 2022

Semina: Ciênc. Agrár.

Self Cite

This study examines the impact of the body mass index (BMI) at calving on the development and postpartum efficiency of cows of Zebu origin. The study involved 87 cows and their calves [pure Nellore (N) or predominant Nellore composition in a cross with Charolais (C) (3/4N1/4C and 5/8N3/8C)]. The mothers were grouped into classes according to their BMI at calving, namely, ‘small’, ‘moderate’ and ‘large’. Body mass index was determined by dividing the body weight of the cows by their length and by hip height and then dividing the result by 10. Cows were weighed at calving, at weaning, at the end of the breeding period and at the diagnosis of pregnancy. Calves were weighed at birth, at early weaning (63 days) and at 210 of age. To evaluate milk yield and quality, milk was collected at 21, 42 and 63 days after calving. Milk yield was measured by the direct method, with manual milking, followed by analysis of the lactose, fat, total solids and crude protein contents. Pregnancy rate was similar between the three BMI groups; however, cows with a lower BMI were more efficient at calving in producing kilograms of calf per kilogram of cow kept. Higher BMI provide higher milk yields, without affecting its quality, as well as heavier calves at early weaning and at 210 days of age.

“…Lemaster, et al, (2017) also reported positive correlations between milk yield and calf development. The heavier weight of calves from the Heavy cows, even at 67 days, has an importance within the production system, because weaning weight is associated with the slaughter age of future steers (Pötter & Lobato, 2003) and with the first service of heifers at 13/15 months of age (Silva, et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Effect of live weight of beef cows on calf production efficiency

Lobato

Restle

et al. 2020

RSD

Self Cite

The objective was to evaluate the development and reproductive performance of beef cows of different body weights at calving were evaluated. Milk yield and calf production efficiency were assessed in secundiparous Braford cows classified at calving according to weight as Light (325.2±3.7 kg), Moderate (347.7±4.0 kg), and Heavy (384.2±4.1 kg). Heavy cows had higher total milk yield than Light cows, but did not differ from Moderate, reflecting in calves weighing at weaning 82.1, 76.6, and 76.9 kg, respectively. Differences on pregnancy rates for Light (90.0%, 18 pregnant cows/2 of eligible cows), Moderate (70.2%, 12 pregnant cows/5 of eligible cows), and Heavy (62.5%, 10 pregnant cows/6 of eligible cows) were not detected. Light cows were more productive and efficient when production performance was adjusted for the pregnancy rates than Moderate and Heavy cows. Production of kilograms of calves adjusted for pregnancy was 20.5, 16.2±0.5, and 14.0±0.5 kg for the Light, Moderate, and Heavy cows, respectively. Heavy and Moderate cows were less efficient as compared with the Light ones for production of calves adjusted for their calving interval. Light cows produce more kilograms of calf/cow, requiring the same amount of milk to produce one kilogram of calf. Light cows also have higher efficiency converting milk into calf weight than Moderate and Heavy cows. The productivity and efficiency of breeding herds should be evaluated by the combination of pregnancy rate and kilograms of weaned calves per cow exposed to breeding.