ABSTRACT This study evaluated different crosses for sustainable beef production in the Meio-Norte, Brazil. Thirty-four cattle [seven Curraleiro Pé-duro (CPD), six Nellore (NEL), seven F 1 ( ½ NEL + ½ CPD ), seven F 2 A ( ¼ CPD + ¼ NEL + ½ Angus ), and seven F 2 S ( ¼ CPD + ¼ NEL + ½ Senepol )] were evaluated on natural pastures in the states of Piauí and Maranhão. The animals were weighed at birth (BW); weaning (WW); 12 (W12), 18 (W18), and 24 months (W24); and slaughter (SW). The morphometric measurements of rump height (RH), withers height (WH), body length (BW), and heart girth (HG) were assessed. Hot carcass weight (HCW), cold carcass weight (CCW), loin-eye area (LEA), backfat thickness (BFT), carcass dressing percentage (DP), water-holding capacity (WHC), cooking loss (CL), shear force (SF), pH, meat color (L*M, a*M, and b*M), and fat color (L*F, a*F, and b*F) were also analyzed. The three-cross animals (F2A and F2S) showed heavier weights from weaning to slaughter as well as higher HCW and CCW. The three-cross cattle produced less methane per kg of meat. The lack of differences between the NEL, F1, F2A, and F2S animals indicates that crossbreeding did not increase their size, which could be detrimental to reproductive efficiency. Loin-eye area, BFT, and DP differed between the genetic groups, with the highest LEA obtained by F2A. Backfat thickness and DP were low in all animals, suggesting a need for increased carcass fatness. Water-holding capacity, CL, SF, pH, a*F, b*F, L*M, and a*M did not differ; therefore, crossbreeding did not affect qualitative or visual aspects of meat and fat. The use of crosses in meat production systems in the Meio-Norte region of Brazil is a viable option to improve sustainability. In this respect, three-cross animals have the best performance.

ABSTRACT The objective of this study was to analyze the genetic evolution of milk production, udder morphology, and animal behavior of Gir dairy cattle. Data were obtained on the predicted breeding values for milk yield of 60,226 cows born from 1968 to 2015 and standardized predicted breeding values for udder conformation and milking behavior of 7,635 cows born from 1987 to 2015. The influence of tested bulls on genetic trends was discussed, with special focus on the period after 1993, the year when the predicted breeding values of the first group of tested bulls were released. The traits of interest were 305-d milk yield, fore udder attachment, rear udder height, rear udder width, teat length, teat thickness, ease of milking, and reactivity. Significant genetic evolution was observed for 305-d milk yield, with increasing annual growth observed from 1993, as the number of cows sired by the best proven bulls increased. Before 1993, no genetic evolution was observed for any of the studied traits. From 1993 onward, all traits showed genetic gains, except fore udder attachment. The use of genetically-tested bulls since 1993 has led to important genetic gains in the Brazilian Dairy Gir population. Before the identification of genetically superior bulls began, many traits showed no improvement. Selection for milk yield has modified the conformation traits of the Gir mammary system. The longevity of the mammary glands of high-yield cows may be impaired due to poor fore udder attachment. Regarding behavioral traits, this population has evolved to less-reactive animals that are easier to milk.

Objetivou-se com este estudo verificar diferenças no desempenho de animais jovens alimentados com dietas contendo grão úmido de milho ou sorgo. Utilizaram-se dois tratamentos experimentais, nos quais a dieta total possuía, como ingrediente energético principal, grão úmido de milho (TMU) ou grão úmido de sorgo (TSU). Noventa novilhos inteiros F1 Red Angus <FONT FACE=Symbol>´</FONT> Nelore, com 8 meses de idade e 240 kg de peso vivo médio inicial, foram alimentados durante 172 dias e divididos nos dois tratamentos, segundo delineamento inteiramente casualizado. Não foi verificada diferença para ganho de peso diário, ganho de peso total e peso final de abate. Com relação à carcaça, a área de olho-de-lombo, a espessura de gordura subcutânea e a espessura de gordura na garupa também não diferiram estatisticamente entre os tratamentos. Concluiu-se que a substituição integral do TMU pelo TSU não alterou o desempenho de bovinos jovens em confinamento.

The differences on performance of young cattle fed diets with high moisture corn or sorghum were evaluated in two treatments, where the main energy source of the total diet was composed of high moisture corn (HMC) or sorghum (HMS). Ninety Angus <FONT FACE=Symbol>´</FONT> Nelore crossbred young bulls, averaging 8 month of age and 240 kg BW and fed during 172 days were allotted to two experimental treatments as a completely randomized design. No treatment effect on average daily gain, total weight gain and slaughter final weight was observed. Regarding the carcass, ribeye area, subcutaneous fat thickness and rump fat thickness also did not differ between treatments. In conclusion, the totally replacement of high moisture corn by high moisture sorghum did not affect performance of feedlot young cattle.

Objetivou-se, com este estudo, verificar as diferenças nas características da carcaça, assim como nos parâmetros qualitativos da carne de novilhos jovens alimentados com dietas contendo silagem de grão úmido de milho ou sorgo. Foram utilizados dois tratamentos experimentais, nos quais a dieta total possuía como ingrediente energético principal a silagem de grão úmido de milho (TMU) ou a silagem de grão úmido de sorgo (TSU). Trinta e seis novilhos inteiros F1 Red Angus <FONT FACE=Symbol>´</FONT> Nelore com 8 meses de idade e peso médio inicial de 240 kg foram alimentados durante 172 dias e abatidos em seguida. O experimento foi conduzido em um delineamento inteiramente casualizado. Houve similaridade para o ganho de peso diário, ganho de peso total e peso final de abate. Não foi verificada diferença para o rendimento de carcaça, assim como para os rendimentos de dianteiro, traseiro e ponta de agulha. Os tratamentos TMU e TSU não afetaram os escores para cor, conformação e acabamento de gordura da carcaça. Marmorização, área de olho-de-lombo, espessura de gordura subcutânea e gordura perirenal, assim como as avaliações químicas da carne (proteína bruta e lipídios totais), também não diferiram entre os tratamentos. As dietas experimentais não afetaram a maciez da carne, assim como as perdas físicas no processo de cozimento (gotejamento e evaporação). Concluiu-se que a substituição integral da silagem de grão úmido de milho pela silagem de grão úmido de sorgo não alterou as características qualitativas e quantitativas da carcaça de bovinos jovens em confinamento.

Thirty-six Angus <FONT FACE=Symbol>´</FONT> Nelore crossbred young bulls averaging 8 month of age and 240 kg BW and fed diets with high moisture corn or sorghum during 172 days were allotted to two experimental treatments (where the main energy source of total diet was composed by high moisture corn - HMC or sorghum - HMS) to evaluate the differences on carcass and meat quality of young cattle. The experiment was analyzed as a completely randomized design. There were similarity for average daily gain, total weight gain and slaughter final weight. No difference was observed for carcass dressing, as for forequarter, hindquarter, and spare ribs. The HMC and HMS did not affected the color scores, conformation and fat distribution over the carcass. Marbling, ribeye area, subcutaneous fat thickness and pelvic fat, as for the chemical evaluations of the meat (crude protein and total lipids) also did not differ between treatments. No treatment effect on meat tenderness and physical losses in the cooking process (dripping, evaporation) was detected. In conclusion, the totally replacement of high moisture corn by high moisture sorghum did not affect carcass and quality meat traits of feedlot young cattle.