Níveis de energia metabolizável para frangos de corte no período de 22 a 42 dias de idade mantidos em condições de estresse de calor

Utilizaram-se 240 frangos de corte machos Hubbard com peso médio inicial de 689+5,27 g, mantidos de 22 a 42 dias de idade, em condições de estresse de calor (31,9+0,29ºC). Foi usado delineamento inteiramente casualizado, com cinco tratamentos (3000, 3075, 3150, 3225 e 3300 kcal de energia metabolizável/kg de ração), seis repetições e oito animais por unidade experimental. Avaliaram-se os efeitos de níveis de energia metabolizável (EM) sobre o desempenho, a qualidade de carcaça e as variáveis fisiológicas de frangos de corte alimentados de forma controlada (93% do consumo voluntário) com rações isoprotéicas. O ganho de peso e a conversão alimentar elevaram-se e o consumo de energia metabolizável aumentou linearmente, em razão do nível de EM das rações. Observou-se que as deposições de proteína e gordura na carcaça foram influenciadas de forma linear crescente, enquanto o peso absoluto da sobrecoxa apresentou variação quadrática. Os pesos absoluto dos pulmões e do coração e o relativo dos pulmões dos frangos de corte foram influenciados pelo nível de EM das rações. O nível de 3300 kcal de EM proporcionou os melhores resultados de desempenho, enquanto o de 3108 kcal resultou em maior deposição de proteína, com menor proporção de gordura na carcaça de frangos de corte mantidos em condições de estresse de calor

Thermoregulatory responses during thermal acclimation in pigs divergently selected for residual feed intake

The objective of this study was to evaluate the performance and thermoregulatory responses during acclimation to high ambient temperature (Ta) of pigs from two lines selected for high (RFI+) or low (RFI−) residual feed intake with the hypothesis that RFI− pigs producing less heat would better tolerate high Ta. Pigs (50 kg initial body weight; 17 per line among which 10 of them were catheterized) were individually housed in a climatic-controlled room where Ta was maintained at 24.2 ± 0.4 °C during 7 days and thereafter at 30.4 ± 0.7 °C during 14 days. Irrespective of Ta, RFI− pigs had lower feed intake (ADFI) and similar average daily gain (ADG) than RFI+ pigs. Whatever the line, ADFI, ADG, and feed efficiency decreased with increased Ta. Overall, the Ta increase resulted in an increase in rectal temperature (RT), skin temperature (ST), and respiratory rate (RR) within the first 24–48 h and, subsequently, in a decrease followed by stabilization. The RT decrease during acclimation occurred 24 h earlier in RFI− pigs than in RFI+. Thyroid hormones and cortisol decreased at high Ta and it was similar in both lines. Based on performance and RT, ST, and RR responses, it seems that selection for low RFI tends to ameliorate pigs’ tolerance to high Ta. Nevertheless, this selection does not induce significant differences between lines in endocrine and metabolite responses during thermal stress

Lisina digestível para leitoas em fase de crescimento Digestible lysine for growing gilts

Oitenta leitoas (24,2±1,52kg) com alto potencial genético para deposição de carne na carcaça foram distribuídas em experimento de blocos ao acaso para avaliar cinco níveis de lisina digestível (Ld) (9, 10, 11, 12 e 13g kg-1) durante a fase de crescimento (63 a 103 dias de idade). Os animais foram alojados em pares e alimentados à vontade. No início e ao final do período experimental, as leitoas foram pesadas e submetidas à análise de ultrassom para avaliação da área de olho de lombo (AOL) e espessura de toucinho (ET). Os níveis de Ld proporcionaram aumento linear (P0,05) dos níveis de Ld sobre o consumo de ração diário (CRD) e ET. Os níveis de 12,0 e 12,5g kg-1 de Ld na dieta, correspondentes, respectivamente, ao consumo de lisina digestível diário (CLdD), de 23,6 e 24,6g, proporcionam os melhores resultados de desempenho e área de olho de lombo de leitoas em fase de crescimento (63 aos 103 dias de idade).Eighty gilts (24.2±1.52kg) with high genetic potential for lean gain were used in a randomized complete block design to evaluate five digestible lysine levels (9, 10, 11, 12 and 13g kg-1) during the growing phase (63 to 103 days of age). Gilts were housed in pair and fed their respective diets ad libitum. At the begging and the ending of the experimental period, gilts were weighed and scanned by ultrasound to measure loin area, as well as fat depth. The digestible lysine levels linearly increase (P0.05) of the treatments on the fat depth and feed intake. The digestible lysine levels of 12 and 12.5g kg-1, corresponding to the intake of 23.6 e 24.6g dia-1, provide the best results of performance and loin area of growing gilts (63 to 103 days old)

Níveis de lisina em rações para fêmeas suínas em lactação

Foram utilizadas 65 porcas (Large White x Landrace) com 217,36 ± 21,35 kg para avaliação de diferentes níveis de lisina total (0,950; 1,025; 1,100; 1,175 e 1,250%) na ração para a fase de 21 dias de lactação. Utilizou-se o delineamento experimental de blocos ao acaso, com cinco tratamentos e 13 repetições, sendo a porca considerada a unidade experimental. O consumo total de ração diário foi fixado entre os tratamentos. Os níveis de lisina da ração não influenciaram o peso das matrizes ao desmame, a perda de peso, a espessura de toucinho (ET) das matrizes, a variação na ET, a perda de gordura corporal, o número de leitões desmamados por leitegada e o intervalo desmama-estro. No entanto, foi verificada redução linear na perda de proteína corporal, em kg e em porcentagem, e na produção de leite diária das matrizes suínas com o aumento do nível de lisina na ração. O ganho de peso da leitegada foi influenciado, reduzindo de forma linear com os tratamentos. Os resultados obtidos neste estudo evidenciaram que, ao consumir menores quantidades de lisina, as matrizes mobilizaram suas reservas corporais protéicas para manutenção do desempenho produtivo. Entretanto, a quantidade de proteína mobilizada por estes animais (2,2 kg, correspondente a 6,45% da proteína corporal) não foi suficiente para influenciar os parâmetros produtivos e reprodutivos. O consumo diário de 45 g de lisina total, correspondente a 40 g de lisina digestível, atende às exigências para os desempenhos produtivo e reprodutivo de fêmeas suínas em lactação, enquanto o consumo estimado de 58,9 g de lisina total/dia, correspondente a 53,5 g/dia de lisina digestível, minimiza a perda de proteína corporal durante a lactação.Sixty-five crossbred sows (Landrace x Large White) averaging 217.36 ± 21.35 kg were used to evaluate increasing dietary total lysine levels (0.950, 1.025, 1.100, 1.175, and 1.250%) during 21 days of lactation. The experiment was analyzed as a randomized block design, with five treatments, 13 replicates of one sow per experimental unit. The daily total feed intake was fixed for all treatments. The dietary lysine levels did not affect sow weight at weaning, body weight loss, backfat thickness (BT), BT change, body fat loss, number of weaned piglets per litter and weaning-to-estrus interval. However, there was a linear decrease on body protein loss expressed as kg and percentage and on daily milk production of sows, as the dietary lysine levels increased. The treatments affected litter weight gain, that decreased linearly. The results of this work showed that sows fed decreasing lysine levels retained significant amounts of body protein reserve to maintain their productive performance. However, the protein mobilization of these animals (2.2 kg corresponding to 6.45% of body protein loss) was not enough to affect the productive and reproductive performance. It was concluded that a daily total lysine intake of 45 g, correspondent of 40 g of digestible lysine meets the requirements for productive and reproductive performance of lactating sows and that they require 58.9 g of estimate total lysine/day, that corresponds to 53.5 g/day of digestible lysine to minimize body protein loss during the lactation

Available phosphorus for 15- to 30-kg pigs kept in hot environment

This experiment was conducted to determine the requirement of available phosphorus (aP) for pigs kept in hot environment. Seventy-two pigs (36 castrated males and 36 females) with initial weight of 15.10±0.31 kg were allotted in a completely randomized block design with six treatments (0.107, 0.214, 0.321, 0.428, 0.535, and 0.642% of aP), six replicates and two pigs (1 castrated male and 1 female) per experimental unit. Pigs were kept in a hot environment with temperature of 34.1±0.8 ºC. The levels of aP influenced the daily weight gain, which increased quadratically up to the estimated level of 0.477%, and feed conversion, which improved quadratically up to the estimated level of 0.457%. The levels of aP also influenced the content of phosphorus in the bone, which increased quadratically up to the estimated level of 0.529%. The available phosphorus requirement of 15- to 30-kg pigs kept in a hot environment, for the best results of daily weight gain, feed conversion and bone parameters are 0.477, 0.457, and 0.529%, corresponding to the estimated daily available phosphorus intakes of 4.75; 4.55 and 5.27 g, respectively

Nutritional plans for boars

The objective of the present study was to evaluate nutritional plans for boars. Four hundred animals of 67 to 135 days of age and initial weight of 27.75±1.61 kg were distributed in a randomized block design with seven nutritional plans for boars (9.0-8.0; 9.0-9.0; 10.0-9.0; 10.0-10.0; 11.0-10.0; 11.0-11.0 and 12.0-11.0 g/kg of digestible lysine from 67 to 107 days and from 108 to 135 days, respectively) with four repetitions and a control plan for barrows (11.0-10.0 g/kg of digestible lysine) with eight repetitions and ten animals each. Uncastrated male swine presented better feed conversion; however they showed a lower marbling degree in relation to barrows, regardless of the nutritional plan. The nutritional plan that corresponds to the sequence of 11.0-10.0 g/kg of digestible lysine from the 67 to the 107 days and from the 108 to the 135 days, respectively, meets the nutritional needs of boars