Suchergebnisse

This study aimed to evaluate the production, reproductive performance, and productive efficiency of predominantly Charolais cows and their calves (Straightbred, ¾ C, ¼ N) according to body size at calving. Sixty-three cow-calf pairs were used and classified into three weight groups: Light (331.3±5.8 kg), Moderate (385.9±5.3 kg), and Heavy (424.4±6.2 kg). The classes were formed using half standard deviations above or below the average weight of the cows at calving. For each pair, the body weight was evaluated at calving, at weaning (63 days), at the beginning and at end of the reproductive period, and at 9 months for the calves. Pregnancy rates were similar (P > 0.05) between weight groups. The calves did not differ (P > 0.05) in terms of body weight and weight gain from calving until pregnancy diagnosis (210 days). The heavy cows had greater weight variations from 210 days to 270 days than the light cows. The calf production rate (kg calf/cow kept in herds) did not differ between weight groups. However, in relation to the weight of the cows at 210 days, light cows were 11.28% and 13.02% more productive (P < 0.05), than moderate and heavy cows, respectively. Light cows were more efficient than the other classes of cows at calving and at 210 days old. Our simulations showed that there were more kilograms for sale in herds of light cows (53.085 kg) than moderate and heavy cows (52.310 and 52.870 kg, respectively), while maintaining the structures of the herd constant. The size of the Charolais cow did not influence the weight of calves from calving until 7 months of age or their reproductive performance provided they were weaned early. The need for space for the maintenance of the cow-calf pair increased as the weight of the cows increased. In herds with smaller cows, higher numbers and a higher production of weight for sale are observed than in herds with moderate and heavy cows. Light cows were the most efficient at calving and during pregnancy diagnosis at 210 days.

This study aimed to assess the probability of meat tenderness in confined cows. For this purpose, CAPES and SciELO platforms were searched for papers under this subject published in Brazil between 2000 and 2015. A total of 43 articles were found, of which eleven were used. Those selected approached the finishing of confined cows and specified animal genetic group, breed, and age at experiment start. Moreover, all these studies evaluated sensory and organoleptic characteristics of meat, following the same method. Each variable was analyzed by logistic regression, using the LOGISTIC procedure of SAS. The factors were evaluated by odds ratio (OR), in which changes in the probability of meat tenderness were estimated by means of an add-on function in regression variable units. Animal age at the beginning of termination, percentages of zebuine blood and heterozygosity, and marbling score are factors that affect (p < 0.30) the chance of beef tenderness. The probabilities of obtaining a tender meat increase when age at termination beginning and zebuine genotype participation are reduced, as well as when heterozygosity (via crosses) and meat marbling score increases.

The development of beef calves born of Charolais (CH), Nellore (N), and Charolais × Nellore crossbred cows with Charolais (CHP) and Nellore (NP) predominance, was evaluated from birth to 12 months of age. The cows were grouped into three age classes: primiparous, young and adult. The net energy requirements for maintenance and gain of the calves were also evaluated, as were the production and availability of energy in the milk of the evaluated cows. We used 93 pairs of contemporary cows and calves maintained in natural pasture. From birth to 21 days of age and from 21 to 42 days of age, the calves of adult cows presented the highest average daily weight gain (ADG), while the calves of young and primiparous cows had similar ADG. The highest net energy requirements for maintenance (NEm) and gain (NEg) were for crossbred and Charolais calves, the latter being similar to Nellore calves. The energy available in the milk of the adult cows was 33% higher than that of primiparous cows. The weight gain of calves was influenced by the age of the cow until weaning. The pre-weaning and post-weaning weights of calves were affected by the genetic group, and adult and young cows produced heavier calves in the pre-weaning period than primiparous cows.

The objective of this study was to evaluate the fatty acid profile of duodenal digesta (experiment I) and of meat of beef cattle (experiment II) fed diets containing different levels of concentrate (220, 400, 590 and 790 g of concentrate/kg of dry matter of the diets). The experiment I was conducted with four Charolais-Nellore steers (460 ± 18.2 kg of BW), with a T-shaped duodenal cannula, using a double 4 × 4 Latin square as an experimental design. In experiment II, 16 crossbred Charolais-Nellore young bulls (192.44 ± 18.2 kg of BW) were randomly distributed in the experimental treatments (220, 400, 590 and 790 g of concentrate/kg of dry matter of the diets). The diets were isonitrogenous (120 g of crude protein/kg of dry matter). The intramuscular fat content was used as a covariant for the statistical analysis of the meat fatty acid profile. The duodenal content of fatty acid C17:0 decreased with increase of concentrate levels, while its content in the meat presented a quadratic variation with the increase of the concentrate levels of the diets, being the lowest values observed for the diet with 400 g of concentrate. The duodenal content of fatty acid C18:1 trans-11 decreased, whereas the content of this fatty acid in the meat increased with the increase of the dietary concentrate levels. The increase in the level of concentrate reduced the content of polyunsaturated fatty acids C18:3 n-3, C20:3 n-6, C20:4 n-6, and C20:5 n-3 EPA in both the duodenal digesta and meat. No difference was observed in the n-6/n-3 fatty acids ratio (mean of 13.96) of the meat between diets. The elevation of the level of concentrate in confinement diets reduces the nutraceutical quality of the meat of Charolais-Nellore young bulls slaughtered at 14-16 months of age due to the reduction of the polyunsaturated fatty acids content important for human health.

The objective of this study was to evaluate the effect of live weight at first mating on reproductive performance in the first and second reproductive years. For that purpose, the reproductive history of 221 heifers mated for the first time between the years of 2003 and 2012 was evaluated. Heifers were grouped into three weight classes at the age of 24 months: 50-59.9% (55%), 60-69.9% (65%), and 70-80% (75%). The pregnancy rate in the first reproductive year in heifers from weight classes 55%, 65%, and 75% was 38.0%, 56.4%, and 69.0%, respectively. The pregnancy rate in the second reproductive year was not affected by weight at first mating (p > 0.05) and corresponded to 41.6%; 42.1%, and 50.4% in the three weight classes, respectively. The weight class of heifers before mating at the age of 24 months affected reproductive performance at first mating but did not increase the pregnancy rate in the second reproductive year.

This study was conducted aiming at measuring the performance and behavior of beef cattle surgically castrated, immunocastrated or non-castrated, finished at 18 months old in Aruana pasture and with energy supplementation. Thirty-nine male bovines with an initial average body weight and age of 284.1 ± 31.4 kg and 14 months old, respectively, were used. The bromatological composition analysis and productive parameters of the pasture did not differ between treatments. The performance of young cattle was not changed by the sexual condition. When evaluating the agonistic behavior, the non-castrated bovine presented a higher number of activities, such as threats and fights, in relation to those immunocastrated. The time spent on the feeder by non-castrated young cattle (56.20 minutes) was higher than that observed for surgically castrated or immunocastrated (41.43 and 32.38 minutes, respectively). The combination between the correct management of Aruana pasture and use of supplementation showed to be promising for finishing bovines. Both surgically castrated and immunocastrated steers demonstrated to be equivalents in the performed evaluations. Therefore, if the farmer chooses castration, the use of immunocastration is suggested. This practice is less invasive, preserves animal welfare more than surgical castration, and has a lower cost.

The objective of this study was to, through a meta-analysis of published data, evaluate the effects of dietary supplementation on the performance of beef cattle grazed on Brachiaria pastures during the rearing and finishing phases of growth. Data from 15 Brazilian studies were analyzed, totaling 462 animals given different types and levels of supplementation. Animals were divided into two categories: 319 in the rearing phase, and 143 in the finishing phase. The reviewed studies evaluated the effects of protein, energy, and protein/energy supplementation on animal performance parameters. Daily weight gain and final live weight were analyzed using forest plots. Daily weight gain during the rearing phase was similar across all supplement types used. Animals given supplementation gained an average of 119 g more per day compared to those who received no supplementation. Specifically, protein supplementation resulted in an increase of 28.22 kg. Animals given supplementation of any kind, represented by the subgroups shown in the plots, gained an average of 24.47 kg more compared to the control group.

This study aimed to assess the effect of sorghum planting patterns on forage response and performance of beef heifers at finishing phase. The experimental period lasted 84 days; treatments consisted of the combination of two interrow spacings (22 and 44 cm) and two sorghum-sowing rates (12 and 24 kg ha?1). Beef heifers, at finishing phase, with initial age of 15 months (± 2.3 months) and average body weight of 262 kg (± 37.95 kg), continuously grazed forage. The experimental design was completely randomized in a 2 × 2 factorial scheme with three repetitions per area. The different planting patterns did not affect (P > 0.05) dry matter production (5,447.78 kg DM ha?1) and accumulation rate (58.47 kg DM ha?1 day?1). Forage accumulation rate, leaf mass, forage mass, leaf supply and forage supply were influenced (P < 0.05) by time. Similar behavior was observed for stocking rate, weight gain per area unit and daily weight gain, with values of 1,172.32 kg of liveweight ha?1, 312.31 kg ha?1; 0.891 kg day?1, respectively. Animal performance had no effect (P > 0.05) from planting patterns, with nearly 4.04 mm of subcutaneous fat thickness and final weight of 330.36 kg. Animal body development showed no significant differences (P > 0.05), with values for length, heart girth and hip height of 132.01, 163.75 and 126.75 cm, respectively. The weight to average height ratio between planting patterns was 2.67 kg cm?1.

The goal of the present study was to evaluatecharacteristics of the carcass and meat of steers and heifers, finished in feedlots and fed different high-grain diets. Forty-five bovines were used: 21 heifers, with an initial age of 32 months and initial weight of 359.9 kg, and 24 steers, with an initial age of 20 months and initial weight of 337.6 kg, from a Charolais × Nelore crossbreed. The animals were divided among the treatments, which were defined by the energy source used in the diet: rice, white oats, or corn; seven heifers and eight steers were used per diet treatment. The animals remained confined until reaching an estimated warm carcass weight of 220 kg. The experimental design was completely randomized, with a 3 × 2 factorial arrangement. Weights at slaughter were higher for animals fed white oats (449.3 kg) or corn (430.4 kg) than for animals fed rice (401.8 kg). Higher carcass yields were found in corn-fed animals. Animals that received rice had lower coverfat thickness. The yields of the rib and hind-quarter commercial cuts were higher for cattle that received white oats or corn. Animals that received corn diets had greater arm circumference than animals that received white oatsand both were larger than animals that were fed rice. The tenderness (5.15 points) and palatability (5.46 points) of rice-fed animals werelower than those of animals fed white oats (5.73 and 6.40 points, respectively) or corn (6.04 and 6.45 points, respectively). Slaughter weights were similar between categories - 424.1 kg and 430.2 kg for steers and heifers, respectively. Steers had higher fore-quarter yield (38.0% vs.37.4%), whereas heifers had a greater carcass length (126.0 cm vs. 123.1 cm). The finishing of cattle with corn- or white oat-based high grain-diets yielded heavier carcasses, with adequate deposition of fat, andbetter performance of principal carcass cuts. Feeding with rice in high-grain diets produced leaner meats, but reduced carcass weight, with greater losses upon cooling and less tender meat. The production of confined heifers or steers ensures similar meat products.

The objective of this study was to evaluate the effect of crude protein substitution of soybean meal with urea (slow-release or otherwise) on the carcass and the meat characteristics of finished steers in confinement. Twenty-seven castrated, purebred and Charolais-Nelore crossbred steers with a mean age of 20 ± 1,5 months and initial mean live weight of 293 ± 31 kg, were distributed in three treatments: Protected Urea (concentrate containing slow degradation urea ); Soybean meal (concentrate containing soybean meal) and Urea Common (concentrate containing common urea). A randomized block experimental design (racial predominance) was used, with three treatments and nine replications, with the animal as the experimental unit. Feeding treatments did not influence the hot and cold carcass weight and yield. The fat thickness that covered the carcass was not altered, according to the diets studied, being on average 3.97 ± 0.94 mm. The measurements and the carcass compactness were not altered by the diets, presenting average values of 127.55; 74.86; 39.86; 38.84 and 25.72 cm for carcass length, leg and arm, arm perimeter and cushion thickness, respectively. A significant difference was observed in marbling, and the meat of the animals treated with soybean meal were higher than those treated with protected urea (3.72 vs 2.28 points).

Dry matter and neutral detergent fiber contents act as physical regulators of voluntary intake in ruminants. Therefore, different levels of these components may interfere with animal performance and require careful assessment of the used raw material. This study was conducted with the purpose to assess the effect of soybean hulls and white oat in distinct or associated uses in the concentrate diet on the ingestive behavior of cattle. Thirty-six steers with an initial mean age of 20 months and initial mean weight of 226 kg were used. The diet was composed of 50% sorghum silage and 50% concentrate based on dry matter. The tested diets were soybean hulls (concentrate fraction composed mainly of soybean hulls), white oat grains (concentrate fraction composed mainly of white oat grains), and mixture (concentrate fraction composed of equal parts of soybean hulls and white oat grains). The experimental design was a randomized block design with 12 animals per diet. The data were compared by the PROC MIXED procedure with repeated measures in time, and the means were compared by the least significant difference test at 5% significance level. Diets presented different contents of neutral detergent fiber (66, 56, and 47%) and lignin (3.2, 3.7, and 4.1%) as the percentage of white oat grain increased in the diet. The total rumination time was lower (447 minutes) for animals that received equal parts of soybean hulls and white oat grains in the diet when compared to animals receiving a diet containing soybean hulls (483 minutes) and white oat grains (495 minutes), with no difference from each other. Animals fed a diet containing soybean hulls and white oat grains showed longer feeding time, a higher number of daily meals, shorter rumination time, shorter time spent chewing, and fewer number of chews per bolus and day. This diet results in a better dry matter and neutral detergent fiber rumination efficiencies.