ABSTRACT. The objective of this study was to evaluate the effect of threonine:digestible lysine ratio in the diet on the physiological variables and weight of organs of light laying hens. Two hundred and ten 47 week-old Dekalb White laying hens were distributed in a completely randomized design, with five levels of threonine (0.507; 0.552; 0.597; 0.642 and 0.677%) and seven replicates of six birds each. The experimental period was 10 weeks, totaling 62 days and more eight days for the animals to adapt. The physiological parameters of cloacal temperature (CT), respiratory rate (RR) and average surface temperature (AST) were recorded weekly (7:00 am, 10:00 am, 1:00 pm, 4:00 pm, and 7:00 pm); after solid and water fasting, the birds were slaughtered to assess the absolute weight of the organs. The time of day influenced (p < 0.05) the physiological parameters RR and AST, and CT showed a significant effect (p < 0.05) of increasing levels of digestible threonine. The total weight of the pancreas, proventriculus and lung showed a significant effect (p < 0.05) of the increase in the levels of digestible threonine. The respiratory rate is affected by the levels of threonine in the diet. The 0.687% level promoted hypertrophy of the pancreas, proventriculus and lung, promoting more significant activity of these organs.

Resumo Este estudo objetivou avaliar o comportamento ingestivo e a preferência alimentar de caprinos criados em Caatinga (Floresta Tropical Seca) degradada em três épocas do ano: transição (chuva-seca), seca e chuva. O experimento foi desenvolvido na Estação Experimental pertencente à UFPB em São João do Cariri-PB, Brasil. Foram utilizados seis caprinos machos mantidos em pastagem com área de 3,2 hectares. A avaliação dos animais foi feita por meio de observação visual e ininterrupta. O delineamento experimental utilizado foi o inteiramente casualizado, com três tratamentos (época de chuva-seca, seco e chuvoso) e seis repetições (animais). As médias foram submetidas ao Teste de Tukey em nível de 5%. Na época de transição (chuva-seca), o tempo gasto pelos animais apresentou semelhanças para gramíneas, herbáceas/subarbustivas, serapilheira, arbustivos/arbóreos selecionados, com exceção das bromélias e cactáceas. Na estação chuvosa, os animais despenderam maior tempo de pastejo consumindo gramíneas. Nessa mesma época, o marmeleiro (Croton hemiargyreus Mill. Arg.) foi a espécie mais selecionada em relação à catingueira (Caesalpinia pyramidalis) e ao pereiro (Aspidosperma pyrifolium). O tempo despendido para atividade de pastejo na época de transição (chuva-seca) foi superior à época chuvosa e seca. Os caprinos, em criação extensiva na Caatinga, apresentam alta plasticidade no hábito alimentar podendo comportarse como animais pastejadores ou ramoneadores.

Abstract This study aimed to assess the ingestive behavior and feeding preference of goats reared in degraded Caatinga (dry tropical forest) during three seasons: transition (rainy-dry), dry, and rainy seasons. The experiment was carried out at the UFPB Experimental Station in São João do Cariri, PB, Brazil. Six male goats kept on pasture with an area of 3.2 hectares were used. The animals were assessed through continuous visual observation. The experimental design was completely randomized, with three treatments (rainy-dry, dry, and rainy seasons) and six replications (animals). Means were submitted to the Tukey test at a 5% level. The time www.revistas.ufq.br/vet spent by animals during the transition season (rainy-dry) had to cite in the article page. similarities for the selected grasses, herbaceous/sub-shrub plants, litter, and shrub/ tree plants, except for bromeliads and cacti. The animals spent longer grazing time consuming grasses at the rainy season. During this season, marmeleiro (Croton hemiargyreus Mill. Arg.) was the most selected species in relation to catingueira (Caesalpinia pyramidalis Tul.) and pereiro (Aspidosperma pyrifolium Mart.). The time spent for grazing activity during the transition season (rainy-dry) was longer than the rainy and dry season. Goats reared extensively in the Caatinga have high plasticity in their eating habits and can behave as grazing or browsing animals.

ABSTRACT This study was designed to assess the effects of feeding space availability on social behavior and performance of housed crossbreed sheep through the use of three different types of feeders. Thirty-six crossbreed ewes (Santa Inês × Dorper; 2-3 years old) with initial body weight of 34.99±4.28 kg were randomly assigned to a 3 × 3 (feeder type × available space at the feeder) factorial arrangement among nine pens. Pens had one of three feeder types (concrete bunk, plastic, or wood barrel) and one of three amounts of available space in the feeder (0.33, 0.25, or 0.20 m animal−1). Total dry matter intake/pen, dry matter intake per animal, total weight gain/pen, daily weight gain/animal, and food waste were evaluated. Percentage of time spent at feeding and frequency of aggressive behaviors/12 h were recorded. We observed a higher total daily weight gain in ewes with a feeding space of 0.33 and 0.25 m animal−1. The wastes were essentially insignificant for wood feeders in all feeding space treatments. The average number of aggressive behaviors was lower (P<0.05) for animals kept in pens with feeding space of 0.33 m animal−1 than for those maintained in pens with feeding space of 0.20 and 0.25 m animal−1. Ewes with feeding space of 0.33 m animal−1 fed simultaneously 54% of the time, while among pens with feeding spaces of 0.25 or 0.20 m animal−1, this period was reduced to 41 and 30%, respectively. An available feeding space of 0.33 m animal−1 is recommended for adult housed ewes, once it favors simultaneous access, lower competitive interactions at the feeder, and less variation in terms of individual weight gain among ewes.

The objective of this study was to evaluate the association of forage cactus with different fiber sources (elephant grass hay - EGH; corn straw - CS, hay of cassava shoots - HCS; fresh sugarcane bagasse - FSB; and hydrolyzed sugarcane bagasse - HSB) on the milk yield and composition and the feeding behavior of lactating Sindhi cows. Five cows with average body weight, average daily milk yield, and average daily 4%-fat-corrected milk yield of 265, 4.95 and 5.22 kg, respectively, were used in a 5 × 5 Latin square design. The effect of experimental diets on milk yield and composition, feeding time (FT), rumination time (RT), idle time, mean values of total chewing time (TCT), number of ruminal boli (NRB), number of rumination chews (NRC), and feed efficiency (FE) and rumination efficiency (RE) expressed as a function of DM and NDF were analyzed. Milk yield in kg/day and corrected to 4.0% fat from the animals that received cactus associated with CS were higher as compared with the treatment with hydrolyzed sugarcane bagasse. The milk composition variables were not influenced by the treatments, and nor were FT, RT, TCT, NRB and NC. Two patterns were observed for FE and RE, with higher efficiency of the diets with EGH, CS and HCS and lower efficiency for diets containing sugarcane bagasse. In this context, Sindhi cows fed forage cactus associated with corn straw, elephant grass hay, and hay of cassava shoots present better performance, feeding efficiency, and rumination responses than those fed forage cactus associated with fresh sugarcane bagasse and hydrolyzed sugarcane bagasse.

The objective of this study was to evaluate the seasonal and daily variation in sexual behavior of Morada Nova breeders raised in the Brazilian semi-arid region. The data were collected from four rams and 114 ewes of the Morada Nova breed - 55 females in the dry season and another 59 in the rainy season. Observations were performed in the dry and rainy seasons, divided into four times of the day: morning (05:01 h to 11.00 h), afternoon (11.01 h to 17.00 h), evening (17.01 h to 23:00 h), and dawn (23:01 h to 05.00 h). Sexual behavior was assessed for a period of 24 h/day, in a breeding season. One ram was used each three days. The behavioral patterns of the rams in view of females were observed during the recognition (sniffing the female urine, bouts of anogenital sniffing, and flehmen reaction), preparatory (exposure of tongue and penis, leg-kicking, and low-pitched bleats), and copulatory (number of mounts, number of ejaculations, and refractory period) phases. The rams were more active during daytime. The animals in the rainy season showed more efficient sexual behaviors by the lower frequency of mounts per ejaculation and greater number of ejaculations in a shorter time. In contrast, courting behaviors such as exposure of tongue, number of mounts, low-pitched bleats, and leg-kicking were more frequent in the dry season. In the semi-arid region with latitudes close to 7°N, Morada Nova rams have a higher intensity of precopulatory behaviors and lower frequency of ejaculations in the dry season.

This experiment was carried to evaluate the effect of forage cactus with different fiber sources (elephant grass hay [EGH], corn straw [CS], hay of cassava shoots [HCS], fresh sugarcane bagasse [FSB], and hydrolyzed sugarcane bagasse [HSB]) on intake, apparent digestibility and macrobiotic protein production of cows. Five cows with 265 kg average body weight, 4.95 kg average daily milk yield and 5.22 kg 4% fat-corrected milk yield were randomly allocated to a 5 × 5 Latin square design. The animals fed cactus associated with CS, EGH and HCS showed higher intake of DM and nutrients. However, regarding the digestibility, diets with sugarcane bagasse showed higher digestibility compared with those with CS and hay. For microbial protein, the excretion of purine derivatives, synthesis of microbial N and microbial protein production were higher in the treatment with CS than in the treatment with sugarcane bagasse. On the other hand, the treatment with EGH and HCS did not have statistical differences compared with the other cases. The mean efficiency of microbial protein synthesis of the experiment was 131 g microbial crude protein/kg of TDN. The treatment with CS showed better efficiency; however, it was statistically superior only compared with FSB. The other treatments did not show statistical difference compared with the other cases. Diets with cactus associated with corn straw, hay of elephant grass or hay of cassava shoots provide higher intake of dry matter and nutrients and better metabolic response compared with diets with cactus associated with sugarcane bagasse for lactating Sindhi cows.

The objective of this study was to analyze the behavior of three genetic groups of confined goats by image monitoring using nine unneutered goats of the Azul, Graúna and Moxotó genotypes. The experimental design was completely randomized, in a 3 × 3 factorial arrangement (genetic groups × periods - morning, afternoon and night), with three replications. Animals were monitored by video cameras placed at the ceiling of each stall for 10 days. There were interaction factors in the frequency of behavioral categories: interaction with the trough, self-cleaning, standing bipedally, social interaction, and other activities. Azul, Graúna and Moxotó native goats kept in the same environment under the same system of containment and feeding show different frequencies and durations in their behaviors, which are influenced by the period of the day.

Objetivou-se com este estudo avaliar o efeito da restrição alimentar sobre o comportamento ingestivo de novilhas da raça Guzerá e Sindi. Foram utilizadas 36 novilhas, sendo 18 de cada uma das raças, distribuídos aleatoriamente em um delineamento inteiramente casualizado, em arranjo fatorial 2 x 3. Os tratamentos utilizados foram de 20 e 40% de restrição em relação ao consumido pelos animais do terceiro grupo que se alimentavam à vontade (sem restrição). Para a análise comportamental utilizou-se o método de amostragem scan com registro temporal em intervalos de cinco minutos durante 24 horas contínuas, estimando-se assim o tempo despendido em alimentação, ruminação e ócio. Em relação às restrições impostas, notou-se que animais que não passaram por restrição alimentar apresentaram maior tempo de alimentação e menor tempo em ócio (p < 0,05), observando-se a mesma eficiência alimentar para novilhas das duas raças em confinamento. Os genótipos estudados quando submetidos até um nível de 40% de restrição alimentar se comportam de maneira igual quanto ao comportamento ingestivo, eficiência alimentar e mastigação merícica. Contudo houve efeito dos níveis de restrição que são alterações nos padrões de comportamento ingestivo, mastigação merícica, apesar de não ter ocorrido alterações na eficiência de alimentação e no tempo de mastigação por bolo.

This study aimed to evaluate the effect of feed restriction on the ingestive behavior of Guzerat and Sindhi heifers. A total of 36 heifers were used, 18 from each breed, randomly distributed in a completely randomized design, in a 2 x 3 factorial scheme. The treatments used were 20 and 40% restriction compared to intake by animals from the third group, which were fed ad libitum (without restriction). For the behavioral analysis, the scan sampling method was used by logging and recording times in five-minute intervals during 24 hours, thus estimating the time spent feeding, ruminating and idling. With regard to the imposed restrictions, it was observed that non-restricted animals showed greater feeding time and lower resting time (p < 0.05); the two breeds showed the same feeding efficiency. When subjected to levels up to 40% of feed restriction, both studied genotypes perform similarly with regard to ingestive behavior, feeding efficiency and cud chews. However, there was an effect of the restriction levels on the patterns of ingestive behavior and cud chews, although there were no changes to feeding efficiency or chewing time per cud.

The objective was to evaluate the effect of electrolyte balance in diets with reduced protein for semi-weighted Bovans Goldline laying hens in the second production cycle. The design was completely randomized with five treatments and seven replicates of six birds per experimental unit. Treatment 1 consisted of a control diet containing 165.0 g/kg crude protein (CP), formulated with the addition of DL-methionine to meet birds requirements during the experimental period. To compose the treatments 2-5 (BE149, BE167, BE185 and BE203), a basal diet with reduced protein (135.0 g/kg CP) supplemented with synthetic amino acids DL-methionine, L-lysine, L- threonine, L-valine and L-tryptophan was formulated. This basal diet was supplemented with potassium carbonate, to replace the inert, so as to provide four levels of potassium (5.86, 6.56, 7.26 and 7.96 g/kg) corresponding to the electrolyte balance of 171, 149, 167, 185 and 203 meq/kg, respectively. There was increased linear effect for feed intake and decreasing linear effect for albumen weight and yolk percentage and quadratic effect for conversion per dozen and per egg mass. Crude protein is recommended at 135.0g/kg with 6.77 g/kg potassium and electrolyte balance of 172.51meq/kg in the diet of semi-weighted laying hens in the second production cycle.

Um experimento foi realizado com o objetivo de avaliar o efeito da utilização de microminerais na forma orgânica sobre o desempenho e a qualidade dos ovos de poedeiras comerciais em final de postura. Foram utilizadas 480 galinhas da linhagem Hisex com 72 a 80 semanas de idade, distribuídas em delineamento inteiramente casualizado, com 6 repetições e 16 aves por parcela. Foram avaliadas cinco dietas: ração basal suplementada com todos os microminerais na forma inorgânica (controle); ração basal suplementada com 50% dos microminerais zinco (Zn) + manganês (Mn) + cobre (Cu) na forma orgânica e 50% na forma inorgânica; ração basal suplementada com 50% de zinco na forma orgânica e 50% na forma inorgânica; ração basal suplementada com 50% de manganês na forma orgânica e 50% na forma inorgânica e ração basal suplementada com 50% de cobre na forma orgânica e 50% na forma inorgânica. Não houve efeito das dietas sobre a produção de ovos, o consumo de ração, a conversão alimentar, a porcentagem e a espessura de casca. As aves que consumiram a ração basal suplementada apenas com zinco ou manganês na forma orgânica produziram ovos com menor peso específico. A utilização da ração basal suplementada com cobre na forma orgânica proporcionou menor perda de ovos. Porém, os melhores resultados foram obtidos com a ração basal suplementada com os microminerais Zn + Mn + Cu na forma orgânica, pois proporcionou menor perda de ovos, maior peso específico e maior peso dos ovos, sendo, portanto, recomendada para a alimentação de poedeiras comerciais em final de postura.

The objective of the present study was to evaluate the effect of using microminerals in organic form on the performance and quality of eggs from commercial laying hens at the end of laying. Four hundred and eighty Hisex strain hens, 72 to 80 weeks of age, were used. A randomized complete design was used, with six replications and 16 birds for each experimental unit. Five diets were evaluated: basal feed supplemented with all microminerals in inorganic form (control); basal feed supplemented with 50% microminerals zinc (Zn) + manganese (Mn) + copper (Cu) in organic form and 50% in inorganic form; basal feed supplemented with 50% zinc in organic form and 50% in inorganic form; basal feed supplemented with 50% manganese in organic form and 50% in inorganic form; and basal feed supplemented with 50% copper in organic form and 50% in inorganic form. There was no effect of diets on egg production, feed intake, food conversion and egg shell percentage and thickness. Birds fed basal feed supplemented only with zinc or manganese in organic form produced eggs with lower specific weight. The use of basal feed supplemented with copper in organic form has minimized egg loss. However, the best results (lower egg loss, higher specific weight and higher weight of eggs) were obtained with the basal feed supplemented with microminerals Zn + Mn + Cu in organic form and, therefore, it is recommended for feeding of commercial laying at the end of laying.

Objetivou-se com este trabalho avaliar o efeito do peso sobre as relações das medidas de comprimento padrão de tilápias-do-nilo (Oreochromis niloticus). Avaliaram-se as medidas: comprimento da cabeça; altura do corpo, medida à frente do 1° raio das nadadeiras peitoral, dorsal, anal e caudal; largura do corpo, medida à frente da inserção do 1º raio das nadadeiras peitoral, dorsal e anal; perímetro, medido à frente da inserção do 1° raio das nadadeiras peitoral, dorsal e anal; e menor circunferência do pedúnculo; e os rendimentos de carcaça, filé, cabeça, nadadeira, pele, vísceras e resíduos. Foram utilizados 80 tilápias, em delineamento inteiramente casualizado com quatro tratamentos (faixas de peso 250 a 300 g; 350 a 400 g; 450 a 500 g, 550 a 600 g) e 20 repetições, considerando o peixe a unidade experimental. As menores variações nas características morfométricas foram observadas na faixa de peso de 450 a 600 g em comparação à faixa de 250 a 400 g. Nas faixas de peso 250 a 300 g, 350 a 400 g, 450 a 500 g e 550 a 600 g, não houve diferenças nos rendimentos de carcaça e filé e nas porcentagens de cabeça, nadadeira, pele e resíduos. A porcentagem de vísceras na faixa de peso 550 a 600 g (10,98%) foi significativamente inferior à obtida nas faixas de 250 a 300 g (12,77%), 350 a 400 g (13,26%) e 450 a 500 g (12,69%). O peso do filé na faixa de peso 350 a 400 g (260,50 g) foi superior ao da faixa de 250 a 300 g (239,95 g). Não houve diferença no peso do filé entre as faixas de peso 450 a 500 g (284,20 g) e 550 a 600 g (292,80 g). As faixas de peso de 450 a 500 g e 550 a 600 g apresentaram valores superiores de peso do filé em comparação às de 250 a 300 g e 350 a 400 g. Considerando o peso do filé, o peso ideal de abate da tilápia é de 450 a 500 g no intervalo de peso de 250 a 600 g.

The objective of this study was to evaluate the effect of weight categories on the relation of the measures of standard length; length of the head; height of the body measured at the front of the 1° ray of pectoral, dorsal, anal and tail fins; width of the body measured at the front of the insertion of 1º ray of pectoral, dorsal and anal fins; perimeter measured at the front of the insertion of the 1° ray of pectoral, dorsal and anal fins and minor circumference of the peduncle and yield of carcass, filet, head, fin, skin, viscera and residues of the Nile tilapia (Oreochromis niloticus). Eighty tilapia were used, in a completely randomized design, with four treatments (weight categories 250 the 300 g; 350 the 400 g; 450 the 500 g and 550 the 600 g) and 20 replications. Each fish was considered an experimental unit. The Nile tilapia presented minors variations in the morphometric characteristics in the weight category 450 to 600 g, when compared with the category 250 to 400 g. The weight category 250 the 300 g, 350 the 400 g, 450 the 500 g and 550 the 600 g provided the same yield of carcass, filet and percentages of head, fin, skin and residues. The percentage of viscera in the 550 the 600 g category (10.98%) was significantly lower when compared to 250 the 300 g (12.77%), 350 the 400 g (13.26%) and 450 the 500 g (12.69%). The weight of filet in the 350 the 400 g category (260.50 g) was higher than the 250 the 300 g category (239.95 g). There was no difference in the weight of fillet between the 450 the 500 g category (284.20 g) and 550 the 600 g (292.80 g). The category 450 the 500 g and 550 the 600 g presented higher values of weight of fillet when compared to 250 the 300 g and 350 the 400 g. According to the weight of fillet found, the ideal weight of slaughter of the tilapia is between 450 and 500 g in a range of 250-600 g.

Este estudo foi conduzido para avaliar as exigências de treonina digestível nas rações de leitoas no período de 30 60 kg, mantidas em ambiente termoneutro. Setenta leitoas, mestiças, com peso inicial de 30,0 ± 0,61 kg, foram distribuídas em delineamento experimental de blocos ao acaso, com cinco tratamentos (níveis de treonina digestível), sete repetições e dois animais por unidade experimental. Os tratamentos corresponderam aos níveis de 0,50; 0,53; 0,56; 0,60 e 0,63% de treonina digestível. Não houve efeito dos níveis de treonina digestível sobre o ganho de peso diário dos animais. A conversão alimentar melhorou, de forma quadrática, com os níveis de treonina digestível e o modelo Linear Response Plateau estimou em 0,52% o nível do aminoácido, a partir do qual a conversão não variou. O consumo de ração diário reduziu com o aumento linear da ingestão de treonina digestivel. A deposição de gordura reduziu de forma linear, enquanto a de proteína não variou com o aumento de treonina digestivel. Os pesos absoluto e relativo dos rins e o absoluto do intestino aumentaram de forma quadrática com os níveis de treonina digestível. No entanto, o peso relativo do intestino aumentou de forma linear. Concluiu-se que o nível calculado de 0,52% de treonina digestível, correspondente a um consumo diário de 9,18 g e a uma relação com a lisina digestível de 63%, proporcionou melhor conversão alimentar para leitoas mantidas em ambiente termoneutro dos 30 aos 60 kg.

This study was carried out to evaluate the requirement of digestible threonine in diets of gilts from 30 to 60 kg, maintained thermoneutral environment. Seventy crossbreed gilts with an initial weight of de 30.0 ± 0.61 kg were used in a randomized blocks design, with five treatments (levels of digestible threonine), seven replicates and two animals per experimental unity. The treatments corresponded of the levels of 0.50; 0.53; 0.56; 0.60; and 0.63% of digestible threonine. No effect was observed of digestible threonine level on daily weight gain of animals. Feed:gain ratio improved in a quadratic way with the digestible threonine level, and the Linear Response Plateau model estimated in 0.52% the level of amino acid, from which the feed conversion did not change. Daily feed intake was reduced with the increase of digestible threonine intake. Fat deposition linearly reduced, while protein deposition did not change with the increase of digestible threonine. The absolute and relative weight of kidneys and the absolute of intestine increased in a quadratic way with the digestible threonine levels, However, the relative weight of intestine increased in a linear way. It was concluded that the calculated level of 0.52% of digestible threonine, corresponding to a daily intake of 9.18 g and a relation with the digestible lysine of 63% provided better feed:gain ratio for gilts maintained in a thermoneutral environment from 30 to 60 kg.

Este estudo foi conduzido com o objetivo de avaliar as exigências de treonina digestível em rações para leitoas no período de 15 aos 30 kg, mantidas em ambiente termoneutro. Setenta leitoas, mestiças, com peso inicial de 15,1 ± 0,4 kg, foram distribuídas em delineamento experimental de blocos ao acaso, com cinco tratamentos (níveis de treonina digestível), sete repetições e dois animais por unidade experimental. Os tratamentos corresponderam aos níveis de 0,54; 0,58; 0,61; 0,65 e 0,69% de treonina digestível. Os níveis de treonina digestível da ração aumentaram o ganho de peso diário de forma quadrática até o nível de 0,61% e a conversão alimentar até o nível de 0,62%. As deposições de proteína e gordura na carcaça dos animais também se elevaram de forma quadrática, atingindo valor máximo no nível de 0,61%. Constatou-se efeito linear dos tratamentos sobre os pesos absoluto e relativo do intestino. O nível calculado de 0,62% de treonina digestível, correspondente a uma relação com a lisina digestível de 67% e a um consumo diário de 7,11 g, proporcionou melhor desempenho de leitoas mantidas em ambiente termoneutro dos 15 aos 30 kg.

This study was carried out to evaluate the requirements of digestible threonine in diets of gilts from 15 to 30kg, maintained in thermoneutral environment. Seventy crossbreed gilts with an initial weight of 15.1 ± 0.4 kg were used in a randomized blocks design, with five treatments (levels of digestible threonine), seven replicates and two animals per experimental unity. The treatments corresponded to the levels of 0.54, 0.58, 0.61, 0.65, e 0.698% of digestible threonine. Digestible threonine levels in the diet increased the daily weight gain in a quadratic way up to the level of 0.61% and the feed:gain ratio up to the level of 0.62%. Protein and fat deposition rates also increased in a quadratic way reaching maximum value up to the level of 0.61%. A linear effect of the treatments was evidenced on the absolute and relative weights of the intestine. The calculated level of 0.62% of digestible threonine corresponding to a relation with digestible lysine of 67% and a daily intake of 7.11 g, provided better performance of gilts maintained in a thermoneutral environment from 15 to 30 kg.

Um experimento foi conduzido para avaliar a influência da redução da PB com a suplementação de aminoácidos na dieta sobre o desempenho de suínos machos castrados mantidos em ambiente de alta temperatura. Foram utilizados 60 leitões mestiços (Landrace x Large White) com peso inicial médio de 29,8 kg, em delineamento inteiramente ao acaso, com cinco tratamentos (17, 16, 15, 14 e 13% PB), seis repetições e dois animais por unidade experimental. As dietas experimentais e a água foram fornecidas à vontade até o final do experimento, quando os animais atingiram o peso médio de 59,9 kg. A temperatura média no interior da sala foi mantida em 32,2ºC, a umidade relativa em 74,4% e o Índice de Temperatura de Globo e Umidade em 82,8. A redução do nível de PB da dieta influenciou o ganho de peso (GP) dos animais, de modo que aqueles alimentados com a dieta com 14% de PB apresentaram redução significativa no GP. O consumo também foi influenciado pelos níveis de PB da dieta, pois foi menor nos animais alimentados com a dieta com 14% de PB em comparação àqueles alimentados com dieta com 16 e 13% de PB. A conversão alimentar não foi influenciada pelos níveis de PB da dieta. Observou-se efeito dos tratamentos sobre as deposições de proteína (DP) e gordura (DG); os animais alimentados com a dieta com 14% de PB apresentaram os menores valores de DG e de DP na carcaça. Os animais que receberam o nível mais elevado de PB apresentaram maiores pesos, absoluto e relativo, dos rins. O nível de PB de dietas para suínos machos dos 30 aos 60 kg em ambiente de alta temperatura pode ser reduzido de 17 para 13%, pois, até esse nível, a redução não influencia negativamente o desempenho e a DP na carcaça, desde que as dietas sejam devidamente suplementadas com aminoácidos essenciais limitantes.

This experiment was carried out to evaluate the influence of the reduction of dietary CP levels and amino acid supplementation on performance of barrows maintained in a high environmental temperature. A total of sixty crossbreed (Landrace x Large White) piglets (average body weight = 29.8 kg) was allotted in a completely randomized experimental design with five treatments (17, 16, 15, 14 and 13% CP), six replications and two animals per experimental unit. Diets and water were suplied ad libitum until the end of the experimental period, when the animals reached the average weight of 59.9 kg. The average temperature in the room was maintained at 32.2ºC and the relative humidity at 74.4%, corresponding to a Black Globe-Humidity Index of 82.8. The reduction of dietary CP level affected weight gain (WG). The animals fed 14% CP diet showed significant WG reduction. Feed intake (FI) also was affected by CP level, and the animals fed 14% CP diet showed smaller FI values than those fed 16 and 13% CP diets. Feed:gain ratio was not affected by treatments. The animals fed the diet with 14% CP showed the smallest values of protein and fat deposition rates in the carcass. The animals fed the diet with 17% CP showed higher kidneys weights. It was concluded that dietary CP level for barrows from 30 to 60 kg body weight, maintained in a high environmental temperature, can be reduced from 17 to 13% with no effect on performance and protein deposition rate in carcass since diets are supplemented with essential amino acids.

Este estudo foi realizado objetivando-se avaliar níveis de treonina digestível em rações para leitoas em crescimento mantidas em ambiente de alta temperatura. Foram utilizadas 70 leitoas mestiças com peso inicial de 14,9 ± 0,56 kg, distribuídas em delineamento de blocos ao acaso, com cinco tratamentos (níveis de treonina digestível), sete repetições e dois animais por unidade experimental. Os tratamentos corresponderam aos níveis de 0,538; 0,577; 0,614; 0,651 e 0,688% de treonina digestível na ração. O ganho de peso diário e o consumo médio diário de treonina aumentaram de forma linear com os níveis de treonina da ração, enquanto, o consumo diário de ração não foi influenciado pelos tratamentos. Embora a conversão alimentar tenha variado de forma linear com os tratamentos, por meio do modelo "Linear Response Plateau" (LRP), estimou-se em 0,587% o nível ótimo de treonina digestível na ração. As deposições diárias de proteína e gordura na carcaça dos animais não foram influenciadas pelos níveis de treonina da ração, que também não influenciaram os pesos absoluto e relativo dos órgãos avaliados. Concluiu-se que, para leitoas dos 15 aos 30 kg, mantidas em ambiente de alta temperatura, o nível de 0,587% de treonina digestível na ração proporcionou a melhor resposta de conversão alimentar, o que representa uma relação treonina:lisina digestível de 63%.

This trial was conducted to evaluate the dietary levels of digestible threonine for growing gilts on heat stress environment. Seventy crossbreed gilts averaging initial weight of 14.9 ± 0.56 kg were assigned to a complete randomized blocks design with five treatments (levels of digestible threonine) of seven replications (two animals per experimental unity). The treatments consisted of the following dietary digestible threonine levels: 0.538, 0.577, 0.614, 0.651, and 0.688%. Daily weight gain and threonine intake linearly increased as the dietary threonine level increased, whereas daily feed intake was not affected. Although feed:gain ratio linearly changed with the treatments, the best dietary digestible threonine level was estimated in 0.587%. Daily depositions of protein and fat in the carcass and absolute and relative weights of the evaluated organs were not affected by the treatments. It was concluded that gilts from 15 to 30 kg on heat stress environment require 0.587% of digestible threonine in the diet to obtain better feed:gain ratio, leading to a threonine digestible: digestible lysine ratio of 63%.