RESUMO Na bovinocultura leiteira, as vacas apresentam mudanças metabólicas importantes durante o período de transição, principalmente aquelas de alta produção, que necessitam de nutrientes em maior quantidade para suprir a demanda requerida. Este estudo teve como objetivo determinar a prevalência de hipomagnesemia subclínica no pré e pós-parto em vacas leiteiras inseridas em sistemas de produção de leite na microrregião de Sousa-PB e município de São João do Rio do Peixe-PB. Para isso foram realizadas visitas quinzenais a 34 propriedades rurais, onde a equipe coletou 357 amostras de sangue por meio de punção venosa, sendo 106 provenientes de vacas em lactação que se encontravam no período de pré-parto e 251 de vacas em lactação inseridas no período de pós-parto. Verificou-se que as propriedades forneciam três tipos de suplemento mineral: suplementação exclusiva com NaCl; suplementação com NaCl + núcleo mineral; e suplementação comercial. As vacas que recebiam a suplementação mineral do tipo comercial corresponderam aquelas com maior prevalência (10,53%) de ocorrência do distúrbio, apresentando ainda diferença significativa (P < 0,05) entre as demais formas de suplementação. Em relação ao período reprodutivo em que as vacas se encontravam, notou- se que aquelas do pós-parto apresentaram maior prevalência de hipomagnesemia subclínica (9,96%) em relação às vacas do pré-parto (8,49%). Porém não houve diferença significative (P > 0,05) entre ambas. Estudos como esse tornam-se fundamentais para alertar produtores rurais e técnicos sobre a ocorrência da hipomagnesemia subclínica na região, além dos prejuízos que os distúrbios metabólicos acarretam.

ABSTRACT In dairy farming, cows display important metabolic changes during the transition period, particularly high-production cows, which need nutrients in greater quantity to meet the required demand. The aim of this study was to determine the prevalence of subclinical hypomagnesemia in pre- and post-partum dairy cows inserted in milk-production systems in the Sousa microregion and the district of São João do Rio do Peixe, both in the State of Paraíba, Brazil. As such, visits were made every two weeks to 34 rural properties, where the team collected 357 blood samples by venepuncture, 106 from pre-partum lactating cows and 251 from lactating cows in the post-partum period. It was found that the properties supplied three types of mineral supplement: a single supplement of NaCl, a supplement of NaCl + mineral base, and a commercial supplement. The cows receiving the commercial mineral supplement had the highest prevalence (10.53%) of the disorder, even showing a significant difference (P < .05) between the other types of supplement. In relation to reproductive period, it was found that the post-partum cows had a higher prevalence of subclinical hypomagnesemia (9.96%) than did the pre-partem cows (8.49%); there was, however, no significant difference (P > .05) between the two. Studies such as this are fundamental for alerting rural and technical producers to the occurrence of subclinical hypomagnesemia in the region, in addition to the damage caused by metabolic disorders.

RESUMO O objetivo do presente estudo foi predizer a composição corporal e da carcaça de novilhas Nelore e suas cruzas com Angus e Simental. Foram utilizadas 60 novilhas de três grupos genéticos, sendo 20 Nelore, 20 Nelore x Angus e 20 Nelore x Simental, destas 12 (quatro de cada grupo genético) foram abatidas no início do experimento (grupo referência). As novilhas foram aleatoriamente distribuídas em nove tratamentos (delineamento inteiramente casualizado), em esquema fatorial 3 x 3, sendo três grupos genéticos e três dietas (30 e 50% da matéria seca da ração em concentrado, além de grupo em mantença) sob confinamento. Doze novilhas (quatro de cada grupo genético) foram alimentadas ao nível de mantença (1,1% do peso corporal em matéria seca) com ração contendo 30% de concentrado e 36 novilhas (12 animais de cada grupo genético) foram mantidas em sistema de alimentação à vontade com 30 (seis de cada grupo) ou 50% (seis de cada grupo) da matéria seca (MS) da ração em concentrado. Após o abate, procedeu-se à dissecação completa da carcaça direita e do corte das 9ª; 10ª; 11ª costelas, retiradas da carcaça esquerda. O corte das 9ª; 10ª; 11ª costelas estimou satisfatoriamente os teores de gordura e osso, no entanto, o teor de músculo foi subestimado em 5,32%. O corte das 9ª; 10ª; 11ª costelas estimou de modo satisfatório a composição química corporal e da carcaça, mas não estima, de modo satisfatório, a composição física da carcaça de novilhas Nelore e suas cruzas com Angus e Simental. Os teores dos constituintes químicos no corpo vazio e na carcaça são estimados de forma adequada pelo corte das 9ª; 10ª; 11ª costelas, quando forem utilizadas as equações propostos por Valadares Filho, Paulino e Magalhães (2006). Os percentuais dos macrominerais podem ser estimados pelo corte das costelas, no entanto, os teores de cálcio, fósforo e magnésio apresentam melhor precisão.

ABSTRACT The aim of this study was to predict the body and carcase composition of Nellore heifers and their crosses with Angus and Simmental bulls. Sixty heifers from three genetic groups were used, 20 Nellore, 20 Nellore x Angus and 20 Nellore x Simmental; of these, 12 (four from each genetic group) were slaughtered at the beginning of the experiment (reference group). The heifers were randomly divided into nine treatments (completely randomised design), in a 3 x 3 factorial scheme of three genetic groups and three diets (30 and 50% of the dry matter of the concentrate feed, in addition to the maintenance group) in feedlot. Twelve heifers (four from each genetic group) were fed at maintenance level (1.1% of body weight in dry matter) with a diet containing 30% concentrate, and 36 heifers (12 animals from each genetic group) were fed ad libitum, with 30% (six from each group) or 50% (six from each group) of the dry matter (DM) from the concentrate feed. After slaughtering, the right-side half-carcase was completely dissected, and the 9 th, 10 th and 11 th ribs removed, from the left-side half-carcase, were cut. The 9 th, 10 th and 11 th rib cut satisfactorily estimated the fat and bone content; however, the muscle content was underestimated by 5.32%. The 9 th, 10 th and 11 th rib cut also satisfactorily estimated the chemical composition of the body and carcase, but not the physical composition of the carcase of Nellore heifers or their crosses with Angus and Simmental. The chemical constituents of the empty body and carcase are adequately estimated from the 9 th, 10 th and 11 th rib cut when the equations proposed by Valadares Filho, Paulino and Magalhães (2006) are used. The percentage of macrominerals can be estimated from the rib cut, however, the levels of calcium, phosphorus and magnesium are the most accurate.

ABSTRACT. The aim of this study was to evaluate the replacement of Tifton 85 hay (Cynodon spp.) by maniçoba hay or silage (Manihot glaziovii Muell. Arg) on sheep intake and performance. Twenty-four male Santa Ines animals were used, with initial body weight of 19.77 ± 1.95 kg and average age of 160 days. The animals were distributed in three treatments (Tifton 85 hay-TH, Maniçoba hay-MH and Maniçoba silage-MS), arranged in a randomized blocks design, with 8 replicates per treatment. The feedlot period lasted for 71 days. The means of the variables were tested by Tukey’s test at 5% probability. Sheep fed MH presented higher dry matter intake (p > 0.05) than those fed TH (1.17 kg day-1 vs 1.06 kg day-1). Neutral detergent fiber intake was higher (p > 0.05) for MH-fed sheep (0.394 kg day-1) when compared to MS (0.340 kg day-1). The digestibility of total carbohydrates was higher (p > 0.05) for MH diet (0.71 g kg-1) than TH (0.67 g kg-1). The average daily gain and body weight at slaughter did not differ (p > 0.05) among treatments. Maniçoba hay or silage can replace Tifton 85 hay in sheep diets.

RESUMO. Este trabalho foi realizado para avaliar os cortes comerciais do dianteiro e traseiro de bovinos de origem leiteira alimentados com farelo da vagem de algaroba. Utilizou-se 25 bovinos machos, não castrados (Holandês-Zebu), distribuídos no delineamento inteiramente casualizado, com cinco animais por tratamento. A ração teve aproximadamente 121,2 e 544,98 g kg-1 de proteína bruta e nutrientes digestíveis totais, respectivamente, e foi composta por feno de capim tifton, farelo de milho, farelo de soja, farelo da vagem de algaroba e sal mineral. A meia carcaça direita de cada animal foi separada entre a 5ª e a 6ª costelas em quarto dianteiro e traseiro, dos quais se obteve os cortes comerciais. Não houve efeito (p > 0,05) da substituição do milho pelo farelo da vagem de algaroba sobre os pesos e rendimentos dos cortes do dianteiro (paleta, peito, acém, cupim e costelas) e traseiro (filé mignon, músculos, patinho, fraldão, chã de fora, lagarto, maminha, chã de dentro, picanha, alcatra, aranha, contra filé, capa do contra filé). O farelo da vagem de algaroba pode substituir o farelo de milho em 100% no concentrado sem que haja alteração nos pesos e rendimentos dos cortes comerciais do dianteiro e traseiro de bovinos de origem leiteira.

ABSTRACT. This study was carried out in order to assess commercial front and rear cuts of dairy-origin cattle fed mesquite pod meal. Twenty-five non-castrated male bovines (Holstein-Zebu), distributed according to a completely randomized design, with five animals per treatment, were used. The feed contained about 121.2 and 544.98 g kg-1 of crude protein and total digestible nutrients, respectively, and was composed of tifton grass hay, cornmeal, soybean meal, mesquite pod meal and mineral salt. The right half carcass of each animal was separated between the 5th and 6th ribs, in front and rear quarters, from which commercial cuts were obtained. There was no effect (p > 0.05) as to the replacement of corn for mesquite pod meal on the weights and yields of front cuts (shoulder, brisket, chuck, hump and flanks) and rear cuts (tenderloin, shank, knuckle, thin flank, flat, eye round, rump tail, top side, cap of rump, rump, cut of rump, striploin, cap of cube roll). Mesquite pod meal can substitute cornmeal in 100% in the concentrate without changes in weight and yield of the commercial front and rear cuts of male bovines of dairy origin.

Objetivou-se avaliar a taxa de deposição de tecidos corporais de novilhas Nelore e suas cruzas com Angus e Simental. Foram utilizadas 57 novilhas de três grupos genéticos, das quais 19 eram do grupo Nelore, 19 Angus e 19 Simental, destas 12 (4 de cada grupo genético) foram abatidas no início do experimento (grupo referência) para estimativa da composição da carcaça dos demais animais. Outras 36 novilhas (12 animais de cada grupo genético) foram distribuídas em seis tratamentos, em esquema fatorial 3x2, de modo a constituir três grupos genéticos (Nelore, Angus e Simental) e dois níveis de oferta de concentrado (30 e 50% da matéria seca da ração em concentrado), com seis repetições por tratamento. As nove novilhas restantes foram utilizadas em um experimento paralelo (quadrado latino) para determinação da digestibilidade das rações experimentais. Ao final do experimento, todos os animais foram abatidos e a composição corporal determinada. O percentual de gordura subcutânea foi maior para as novilhas Angus. Os constituintes químicos do peso de corpo vazio e do ganho de peso de corpo vazio não sofreram efeito dos grupos genéticos. Constatou-se que o cruzamento entre fêmeas Nelore com animais Angus, bem como o nível de concentrado melhoram o padrão de deposição dos tecidos corporais.

The objective of this work was to evaluate deposition pattems of body tissues of Nellore and crossbreed with Angus and Simmental heifers. Fifty seven heifers (19 Nellore, 19 Angus and 19 Simmental) were used, being 12 heifers (four in each genetic group) slaughtered before the beginning of the experiment as the baseline group. Thirty six (twelve in each genetic group) were ad libitun fed with 30 (six in each group) and 50% (six in each group) of dry matter diet in concentrate. The animals were in a completely randomized design, 3x2 factorial (tree genetic group and two diet), with six replicates per treatment. Nine remaining animals were used for a digestibility trial. At the end of the experiment all these animals were slaughtered and its corporal composition determined. The percentage of subcutaneous fat was greater for Angus heifers. Chemical constituents of empty body weight and empty body gain there did not suffer effects of genetic group. The crossing between Nellore and Angus, as well as the level of concentrate improve carcass characteristics and pattern of deposition of body tissues.

The objective of this study was to determine the energy nutritional requirements for females of Nellore, Nellore × Angus and Nellore × Simmental fed on two levels of concentrate. Sixty heifers from three genetic groups were used: 20 Nellore, 20 Nellore × Angus and 20 Nellore × Simmental. Twelve belonged to the reference group (four of each genetic group) and were slaughtered at the beginning of the experiment. Another 12 heifers (four of each genetic group) were fed on the maintenance level and 36 heifers (12 animals of each genetic group) were kept in feeding system ad libitum with 30 (six in each group) or 50% (six of each group) dry matter concentrate. Animals were randomly assigned to six treatments in a 3 × 2 factorial arrangement (three genetic groups and two diets) with six replicates per treatment. Nine more heifers were used in a parallel experiment to estimate the apparent digestibility coefficients (three from each genetic group). Net energy requirements were estimated by the equation of retained energy as a function of metabolic empty body weight (EBW0.75) and empty body weight gain (EBWg). Requirements of metabolizable and net energy were estimated for maintenance by the equation of heat production as a function of metabolizable energy intake. Using the combined equation RE (retained energy; Mcal/day) = 0.0703 × EBW.75 × EBWg1.128 to predict net energy requirements for weight gain is recommended. The requirement of metabolizable and net energy for maintenance of all groups is 70.55 and 106.53 kcal/kgEBW0.75/day, respectively. Use efficiencies of metabolizable energy for gain and maintenance are 36.41 and 66.23%, for the three genetic groups respectively.

This study aimed to determine the protein requirements for females of Nellore, F1 Nellore × Angus and F1 Nellore × Simmental fed on two concentrate levels (30 and 50%). Sixty heifers from three genetic groups with 18 months of age were used: 20 Nellore, 20 Nellore × Angus and 20 Nellore × Simmental. Twelve heifers of the reference group (four of each genetic group) were slaughtered at the beginning of the experiment. Another 12 heifers (four of each genetic group) were fed on the level of maintenance and 36 heifers (12 animals of each genetic group) were kept in power system ad libitum with 30% (six of each group) or 50% (six of each group) dietary dry matter in concentrate. Heifers were randomly assigned to six treatments in a 3 × 2 factorial arrangement (three genetic groups and two diets) with six replicates per treatment. Nine more heifers (three from each genetic group) were used to estimate the apparent digestibility coefficients of food in a parallel experiment. A model was fitted according to the protein retained as function of the gain of empty body weight (EBW) and retained energy (RE) to calculate the protein net requirements. To estimate the metabolizable protein requirements for maintenance the consumption of metabolizable protein was contrasted with EBW. The joint use of the equation net protein gain (NPG) = 197.40 × EBWg - 11.14 × RE is recommended to predict the protein net requirements for weight gain. Protein and metabolizable protein net requirements for maintenance are 1.07 and 3.88 g/EBW0.75/day, respectively. The use efficiency of metabolizable protein for gain of all genetic groups is 37.04%.