ABSTRACT The objective of this paper was to investigate the availability of betaine present in fine wheat bran (FWB) in diets for growing pigs. We used thirty crossbred intact males, housed individually in metabolic cages and distributed in a randomized block design, with five treatments and six replicates. Blocks consisted of two periods of 15 days. Average initial body weights were 32.00±1.30 and 44.90±1.32 kg, in the first and second periods, respectively. Treatments were modified only at the level of methionine plus cysteine (Met+Cys) required and the Met+Cys sources, consisting of a negative control (NC), formulated with 80% of Met+Cys requirements, and four positive controls (PC): PCMet - NC supplemented with 1.2 g kg−1 of DL-methionine; PCBet - NC supplemented with 0.9 g kg−1 of anhydrous betaine; PCFWB - diet formulated with FWB; and PCFWB+Met - PCFWB supplemented with 1.0 g kg−1 of DL-methionine. No differences were observed on performance-related variables or on the digestibility coefficient of dry matter. Conversely, the digestibility coefficient of crude energy was lower when pigs were fed FWB and could be associated to the higher fiber content of FWB feeds. Digestible energy of feeds was higher for FWB diets, while the metabolizable energy of FWB diets did not differ from PCMet and PCBet. Nitrogen intake and apparent absorption were lower when pigs were fed FWB, but nitrogen retention, protein utilization, and biological value of the feed protein were the same among PC treatments, indicating that nitrogen from diets was used by pigs with the same efficiency, and is supported by no differences in performance-related variables. The FWB composition showed 12 g of betaine kg−1, which is available to maintain nitrogen retention and performance.

Resumo Este estudo objetivou avaliar o efeito da energia metabolizável da dieta (EM; 3,40, 3,60 ou 3,80 Mcal/kg) e do peso ao desmame (PD; 4,5 ± 0,4 e 6,7 ± 0,5 kg) sobre o balanço de nitrogênio (BN) e a metabolizabilidade da energia de leitões. 32 leitões machos castrados foram alojados individualmente em gaiolas de metabolismo por 28 d em um arranjo fatorial 2 x 3 com cinco animais por tratamento, exceto os tratamentos leve e 3,80 Mcal/kg EM e pesado e 3,40 Mcal/kg EM, que tiveram 6 animais por tratamento. As dietas foram formuladas para manter constante a razão nutriente:energia. O BN foi avaliado em três períodos, via coleta total de fezes e urina. Leitões pesados apresentaram 14% maior N ingerido, absorvido e retido no período inicial e total (P<0,05). Os níveis de EM aumentaram linearmente o N ingerido, absorvido e retido no período inicial e total (P<0,05). Em todos os períodos avaliados, a metabolizabilidade da energia aumentou linearmente com o aumento dos níveis de EM (P<0,05). Conclui-se que leitões desmamados pesados apresentam melhor eficiência na retenção de N. Além disso, o aumento da EM da dieta melhora a retenção de N e a metabolizabilidade da energia da dieta.

Abstract This study aimed to evaluate the effects of dietary metabolizable energy (ME; 3.40, 3.60, or 3.80 Mcal/kg) and weaning weight (WW; 4.5 ± 0.4 and 6.7 ± 0.5 kg) on nitrogen balance (NB) and gross energy metabolizability in weanling piglets. In total, 32 barrow piglets were individually housed in metabolic cages for 28 d in a 2x3 factorial arrangement with five barrows per treatment. Only light and 3.80 ME and heavy and 3.40 ME/kg treatments had six barrows per treatment each. The diets were formulated to maintain a constant nutrient to ME ratio. Nitrogen balance was evaluated in three periods through total collection of feces and urine. Heavy piglets had 14% greater N intake, absorption, and retention in starter and total periods (P<0.05). The increasing in the levels of dietary ME linearly augmented N intake, absorption, and retention during starter and total periods (P<0.05). The dietary ME levels linearly increased energy metabolizability in all periods (P<0.05). In conclusion, heavy weaned piglets had better efficiency in nitrogen retention. Besides, increasing dietary ME levels can improve the N retention and the metabolizability of dietary energy.

ABSTRACT This study was conducted to evaluate the effects of dietary metabolisable energy (ME: 3.25, 3.40, 3.55, or 3.70 Mcal kg−1) and weaning weight (WW: light 4.0±0.7 kg, and heavy: 6.3±0.6 kg) on productive response and energy utilization of weaned piglets. Sixty-four male piglets were housed in 32 metabolic cages (two animals per cage) during the first 14 d postweaning. At day 15, only one animal per cage was kept until day 28. Body composition, energy, and nutrient deposition rates and energy utilization efficiency were measured through a comparative slaughter procedure. Piglets with light WW had a poorer feed conversion ratio and lower weight gain and feed intake when expressed per live weight. Increased ME led to greater daily fat deposition in the empty bodies (defined as weighted mean of the carcass + organs + blood, no intestinal content), while light WW piglets had a reduced protein deposition. Light WW piglets increased heat production with increased ME, but no effect was seen for the heavy WW piglets. By contrast, heavy WW piglets increased empty body gross energy as ME increased, while no influence was observed on light WW piglets. Increasing dietary energy levels did not contribute to the subsequent growth performance of piglets that were lighter at weaning. The lack of interaction between weaning weight and dietary ME content on growth performance does not support the hypothesis that light piglets at weaning do not exhibit compensatory growth because of limitations in energy intake.