Interactive effects of dietary amino acid density and environmental temperature on growth performance and expression of selected amino acid transporters, water channels, and stress-related transcripts

Exposure to heat stress (HS) is one of the challenges facing the broiler industry worldwide. Various nutritional strategies have been suggested, such as altering dietary concentrations of some nutrients. Thus, we evaluated feeding different amino acid (AA) densities on live performance, Pectoralis (P.) muscles, and expression of selected AA transporters, water channels, and stress-related transcripts in a fast-growing broiler strain. Ross 308 chicks (n = 576) were randomly assigned to 4 dietary treatments (24 reps, 6 chicks per rep), differing in AA density (110, 100, 90, and 80% of a breeder's AA specifications). During 24 to 36 days of age, half of the birds were kept at a thermoneutral (TN) temperature of 20°C, whereas the other half were subjected to HS at 32° C for 8 h daily, making the treatment design a 4 × 2. The results revealed no interaction between housing temperature and AA density on growth performance or P. muscles weights. Feeding 80% AAs depressed BWG, FCR, and P. muscles at 36 d (P < 0.001). There was an interaction (P < 0.001) between AA density and temperature on the expression of all examined genes. Reducing the AA density beyond 100% upregulated the expression of AA transporter (CAT1, B⁰AT, b^0,+AT, SNAT1, LAT1), HSP70, HSP90, glucocorticoid receptor (GR), and AQP3 in the TN birds’ jejunum. Whereas in the HS birds, inconsistent expressions were observed in the jejunum, of which CAT1, B⁰AT, and LAT1 were markedly downregulated as AA density was reduced. In P. major of TN birds, reducing AA density resulted in upregulating the expression of all AA transporters, HSP70, GR, and AQP1, while downregulating HSP90 and AQP9. In contrast, AA reduction markedly downregulated CAT1, B⁰AT, and LAT1 in the P. major of HS birds. These findings indicate that the dietary AA level alters the expression of various genes involved in AA uptake, protein folding, and water transport. The magnitude of alteration is also dependent on the housing temperature. Furthermore, the results highlight the importance of adequate AA nutrition for fast-growing chickens under HS.

Effects of lysophospholipid supplementation to reduced energy, crude protein, and amino acid diets on growth performance, nutrient digestibility, and blood profiles in broiler chickens

Two experiments investigated the effects of lysophospholipid (LPL) supplementation on low-energy and low-nitrogenous diets for broilers. A total of 300 one-day-old male chicks (Ross 308) was allotted to 5 treatments in a completely randomized design. Each group consisted of 6 replicates with 10 birds each. Experimental diet I included positive control (PC) having 3,025 (starter), 3,150 (grower), and 3,200 kcal/kg (finisher) of ME; negative control (NC) was 150 kcal/kg of ME lower than PC, and LPL-05, LPL-10, and LPL-15 treatments were NC + 0.05%, 0.10%, and 0.15% of LPL supplementation, respectively. Experimental diet II included positive control (PC) having a formulated amount of crude protein including Lys and Met + Cys that met the Ross 308 standards; negative control (NC) was 4% lower CP and AA than PC; other treatments were supplemented with LPL at 0.05% (LPL-05), 0.10% (LPL-10), and 0.15% (LPL-15) into the NC, respectively. Experiment I showed that growth performance linearly increased as the LPL inclusion increased (P < 0.001). Broilers fed LPL-10 and LPL-15 increased digestibility of DM (P < 0.05), crude protein (P < 0.01), and total amino acids (P < 0.01) compared to NC. Serum glucose (P < 0.01) and high-density lipoprotein (P < 0.05) concentrations were greater in groups fed LPL-10 than those fed PC. Furthermore, leg muscle increased in birds fed LPL-10 compared with NC (P < 0.05). Experiment II observed a linear response to LPL supplementation in the whole period, in terms of body weight gain (P = 0.015) and feed conversion ratio (P = 0.027). Feeding of 0.15% LPL had promising effects on digestibility of crude protein and ether extract compared with NC (P < 0.01 and P < 0.05, respectively). Overall, LPL could be considered as a feed additive to reduced energy (−150 kcal/kg) or nitrogenous diets (−5%) in order to improve growth performance and nutrient digestibility without adverse effects on lymphoid organs and hepatic enzyme of broilers.

Influência da via de fornecimento do cloreto de sódio – água ou ração – em frangos de corte de um a sete dias de idade

RESUMO Estudou-se a via de fornecimento de cloreto de sódio (NaCl) – água ou ração – sobre o desempenho de frangos de corte, consumo de água, desenvolvimento dos órgãos, metabolizabilidade da matéria seca (MMS), retenção de nitrogênio (RN), energia metabolizável aparente corrigida para nitrogênio (EMAn), matéria seca das excretas (MSex) e composição de carcaça. Foram utilizados 120 frangos da linhagem Ross 308, distribuídos em três tratamentos com quatro repetições de 10 aves cada, num delineamento completamente casualizado. De um a sete dias de idade foram submetidos a três formas de suplementação de NaCl (0,47% de Na): 100% na ração; 50% na ração e 50% na água (50% ração:50% água); e 100% na água. Durante o período de oito a 21 dias as aves receberam uma dieta única, com NaCl via ração. De um a sete dias não houve diferença no Consumo de Água, Consumo de Ração e Ganho de Peso; porém, NaCl via água proporcionou melhor CA do que por ambas as vias (p < 0,07). Aos 21 dias de idade não foram observadas diferenças significativas no desempenho, no peso relativo do coração, fígado e moela e no comprimento relativo do intestino. Não houve resposta à via de fornecimento para EMAn e MSex em pintos de quatro a sete dias de idade; no entanto, as aves que receberam o NaCl via água de bebida, exibiram menor MMS e RN (p < 0,05) no mesmo período. Conclui-se que o NaCl pode ser adicionado tanto na ração quanto na água, sem ocasionar prejuízos ao desempenho produtivo dos frangos de corte na fase pré-inicial.