Alexandre Pereira dos Santos

Níveis de ractopamina para suínos machos castrados em terminação mantidos sob estresse por calor

Avaliaram-se o desempenho, as caracteristicas quantitativas de carcaca e as respostas viscerais de suinos machos castrados mantidos em ambiente de estresse por calor e alimentados com dietas suplementadas com ractopamina. Foram utilizados 48 animais com peso inicial de 67,3 ± 3,8 kg, distribuidos em delineamento em blocos casualizados, com quatro niveis de ractopamina (0, 5, 10 e 20 mg/kg), cada um com seis repeticoes de dois animais. O periodo experimental foi de 28 dias. A temperatura do ar foi de 31,8 ± 2,0oC, a umidade relativa foi de 72,6 ± 10,2% e indice de temperatura de globo e umidade (ITGU) de 82,7 ± 2,8. Os niveis de ractopamina nao influenciaram o consumo diario de racao, mas melhoraram a conversao alimentar e aumentaram o ganho diario de peso e o peso final dos animais. As caracteristicas quantitativas de carcaca nao foram influenciadas pelos niveis de ractopamina. Os pesos de figado e dos rins aumentaram de forma linear de acordo com os niveis de ractopamina nas dietas, ao passo que o peso dos demais orgaos e o comprimento do intestino delgado nao foram afetados pela suplementacao com ractopamina. O nivel otimo de ractopamina para melhor desempenho de suinos machos castrados sob estresse por calor e de 20 mg/kg e nao altera as caracteristicas quantitativas da carcaca.

Energia líquida e ractopamina para leitoas em terminação sob altas temperaturas ambientais

The objective of this paper was to assess net energy (NE) levels and ractopamine in the diet of finishing gilts maintained under high temperature environment (29.5±2.3°C). Forty gilts were used, with initial weight of 69.3±2.8kg, distributed in a randomized block design, in a factorial scheme 2x4 (0 and 20ppm of ractopamine; and 2,300; 2,424; 2,548 and 2,668kcal/kg NE kg-1 of feed), and five replications and one animal each. There was interaction (P<0.05) between NE levels and ractopamine, and the inclusion of 20ppm of ractopamine in the diets containing 2,548 and 2,668kcal reduced (P<0.05) backfat thickness and increased (P<0.05) the percentage of lean meat of carcasses. The use of ractopamine improved (P<0.05) feed gain ratio and increased (P<0.05) the amount of lean meat in carcasses. It was concluded that ractopamine at a dose of 20ppm provides benefits in performance and carcass traits of gilts under heat stress and this effect is more positive in diets containing higher energy levels (2,548 and 2,668kcal of NE kg-1).

Restrição alimentar para suínos machos castrados e imunocastrados em terminação

The objective of this study was to evaluate the performance and carcass quantitative characteristics of barrows and immunocastrated swine fed ad libitum or under quantitative feeding restriction. Two hundred and forty animals were used, with initial weight of 91.49±3.26kg, distributed in a randomized blocks design, in a factorial scheme 2x2 (two management and two food categories), with four replicates of 15 pigs each. Pigs submitted to dietary restriction had lower consumption (P 0.05) between castrated and immunocastrated. Pigs fed ad libitum had higher (P 0.05) among the factors on carcass traits. The restriction did not affect (P>0.05) carcass traits. Immunocastrated pigs had lower (P<0.05) back fat thickness and higher percentage of lean meat. Dietary restriction improves feed conversion of castrated pigs. The dietary restriction affects weight gain and does not affect carcass characteristics of barrows and immunocastrated. Immunocastrated pigs have higher performance, lower back fat thickness and a higher percentage of lean meat compared to the castrated.

Duração da suplementação de ractopamina em dietas para leitoas em terminação mantidas sob alta temperatura ambiente

The study was conducted to evaluate the duration of the supplementation of ractopamine in the diet of finishing gilts maintained under high temperature environment. Forty eight females, with initial weight of 70.4±2.6kg were used. The pigs were distributed in randomized blocks design of six treatments (supplementation of ractopamine for 0, 7, 14, 21, 28 and 35 days pre-slaughter) and four replications, each experimental unit consisted of two animals. The final weight and daily feed intake were not affected (P>0.05) by treatments. The weight gain increased and the feed conversion decreased linearly (P 0.05) by duration of supplementation of ractopamine in the diet. The weights of the lungs, heart, liver, kidneys and spleen were not modified (P>0.05) by treatments. It was concluded that inclusion of 20ppm of ractopamine in the diet of finishing gilts maintained under high temperature environment during 28 days maximizes the response of daily gain and during 35 days maximizes the response to feed conversion. However, the inclusion of the additive does not alter the quantitative characteristics of carcass and does not affect the development of the viscera.

Avaliação técnico-econômica de suínos machos imuno e cirurgicamente castrados

This study was conducted to evaluate the technical and economic performance and determine profitability through the economic sensitivity analysis of immune (IM) and male pigs surgically castrated (SC). Two experiments were conducted in a completely randomized design, consisting of two treatments (IM and SC) with eight replicates of 10 animals each, totaling 160 pigs per experiment. It was found that IM pigs have lower feed intake and feed conversion during the growth phases in relation to SC. In the finishing phases, IM have better weight gain, feed conversion, carcass yield and lean meat percentage in relation to SC. The use of IM increases the profitability in pig production. The analysis of profitability differential between IM and SC should consider all stages of creation, since the differential performance of not castrated pigs during growth influences economic results of production.

Digestible phosphorus levels for barrows from 50 to 80 kg

This study was carried out to evaluate the levels of digestible phosphorus in diets for barrows with a high potential for lean meat deposition from 50 to 80 kg. Eighty barrows, with an initial weight of 47.93±3.43 kg, were distributed in completely randomized blocks, with each group given five levels of digestible phosphorus (1.86, 2.23, 2.61, 2.99, and 3.36 g kg−1). There were eight replicates, and two animals per experimental unit. Phosphorus levels did not significantly influence feed intake, weight gain, or feed conversion ratio. Daily digestible phosphorus intake increased linearly as levels of phosphorus in the diet were increased. Phosphorus levels did not significantly influence muscle depth, loin eye area, backfat thickness, or the percentage and quantity of lean meat in the carcass. A linear increase was observed for feeding cost as the levels of digestible phosphorus in the diet were increased, and the level of 1.86 g kg−1 cost 29.4% less when compared with the level of 2.61 g kg−1. The dry matter, natural matter, the coefficient of the residue, and volatile solids of the waste were not significantly influenced by phosphorus levels. Conversely, it was possible to observe an increasing linear effect for total solids, total phosphorus, and total nitrogen in the waste of animals receiving diets with increased levels of digestible phosphorus. The level of 1.86 g kg−1, which corresponded to a daily intake of 4.77 g−1 of digestible phosphorus, meets the requirements of barrows weighing 50 to 80 kg.