Performance, body development and ingestive behavior of Nelore and crossbred heifers finished in a grazing system.

The aim of this experiment was to evaluate growth, body development and ingestive behavior of Nelore and crossbred heifers. Twenty-two contemporary heifers (eight Nelore, seven Nelore × Angus (½ Angus) and seven Nelore × Pantaneiro (½ Pantaneiro) crosses) were evaluated. The variables evaluated were weight, subcutaneous fat thickness [assessed by ultrasound in the longissimus dorsi (SFT) and biceps femoris (SFTP8)] morphometric measures and ingestive behavior (determined between 7 am and 5 pm). The daily gain differed between the breeds (P < 0.05), being greater for the ½ Pantaneiro than Nelore and equal to ½ Angus at the end of the study. The ½ Angus heifers differed (P < 0.01) from the other breeds for SFT (4.36 mm), with no difference between Nelore (2.77 mm) and ½ Pantaneiro (3.38 mm). The SFTP8 was greater (P < 0.01) (5.36 mm) in ½ Angus heifers than t others crossbreed, and greater in ½ Pantaneiro than in Nelore (4.28 vs 3.29 mm). The heart girth and rump width between the ilia were larger (P < 0.01) for the ½ Angus than ½ Pantaneiro and Nelore (169 cm; 41.6 cm, respectively). Substernal height was greatest (P < 0.01) for the Nelore (69.1 cm), reflecting the greater anterior and posterior height. The ½ Angus spent the longest time (P < 0.05) walking and less time grazing. Idleness also differed (P < 0.05) throughout the day. Crossbred heifers exhibited better performance and development than Nelore. The grazing pattern of ½ Pantaneiro heifers was identical to Nelore, but walked less, gained more weight, and exhibited better carcass finishing.

Performance of Pantaneira breed cows in precision grazing system.

Use of a grazing system that takes into account the ingestive behavior of animals and the physiological characteristics of plants maximizes land use and promotes positive effects on the environment. In this sense, the objective of this study was to evaluate the performance of Pantaneira breed cows, kept in rotated grazing in Mombasa grass (Megathyrsus maximum), with different grazing times. Fifty animals were divided into two treatments: Continuous T1: 24 h and T2-Inverted: 12 h. The experiment lasted 98 days, being determined the production and nutritional quality of the forage, digestibility, intake, and performance of the animals. The design was randomized blocks at 5% probability, with the means compared by the F test. The design used was completely randomized at 5% probability by the T test. There was no significant difference for biomass production (P > 0.05). However, after grazing the Inverted group, the forage showed a lower percentage of leaves and an increase in neutral detergent fiber and acid contents and total carbohydrates, and a reduction in crude protein and ether extract values, as well as a higher digestibility (P < 0.05). The animals of the Continuous group intaked more forage (P < 0.05). The Inverted group had a higher average daily weight gain, in addition to a lower feed conversion (P < 0.001). The animals in the Control group spent more time eating (P < 0.0001) and sleeping (P < 0.0001), while the animals of the Inverted group spent more time in idleness (P < 0.0001) and interacting (P < 0.05). There was no difference in rumination time between treatments (P > 0.05). It was concluded that Inverted grazing improved the quality of Mombasa grass and the performance of cows.

Shade-seeking behavior and grazing activity of Pantaneira and Girolando heifers.

This study aimed to model and compare the shade-seeking behavior and grazing activity of Pantaneira and Girolando heifers by time of day. Eight heifers were used, four Pantaneira and four Girolando (3/4 Holstein × 1/4 Gir). The animals were about 18 months old and weighed 328 ± 14 kg (Pantaneira) and 430 ± 28 kg (Girolando). Shade-seeking behavior and grazing activity were recorded during the summer from 06:00 to 18:00 h in 10-min intervals, totaling 288 observations for each breed. A binary regression model was developed by means of a Bayesian approach considering logit, probit, cloglog, and Cauchy link functions. The most parsimonious model was constructed using the Cauchy function. The variables varied according to the time of day. Heifers of both breeds were more likely to graze toward the end of the day, when ambient temperatures were lower. Girolando heifers were more likely to seek shade between 06:00 and 14:00 h. From 12:00 to 13:00, the probability of seeking shade between breeds differed 22 percentage points. Pantaneira heifers were more likely to graze from 06:00 to 13:00 h, and their probability of grazing at 11:00 h was 21 percentage points higher than that of Girolando heifers. The results suggest that Pantaneira heifers are more heat-tolerant.