RESUMEN
The nutritional composition of diets and the provision of exogenous phytases play important roles in animal performance. Therefore, we evaluated the individual and combined impact of metabolizable energy (ME), digestible lysine (dLys), available phosphorus (avP) and calcium (Ca), and phytase dose (1,000 or 2,000 FTU/kg) on the growth performance, feed efficiency, phosphorus digestibility, and bone ash content of broiler chickens from 10 to 42 d of age. Experimental diets were formulated in a Box-Behnken design to contain various levels of ME (11.9, 12.2, 12.54, or 13.1 MJ/kg), dLys (0.91, 0.93, 0.96, or 1.00%) and avP/Ca (0.12/0.47, 0.21/0.58, or 0.33/0.68%). The effect of phytase was expressed in terms of the extra nutrients released. The diets were formulated to have consistent phytate substrate contents (0.28% in average). Body weight gain (BWG) and feed conversion ratio (FCR) were described via polynomial equations (R2 = 0.88 and 0.52, respectively), with interconnections between variables (ME, dLys, and avP/Ca). No interaction was observed among variables (P > 0.05). Metabolizable energy was the most important factor affecting BWG and FCR (linearly; P < 0.001). Reducing ME content from 13.1 to 11.9 MJ/kg in control diet resulted in a 6.8% decrease in BWG and a 3.1% increase in FCR (P < 0.001). The dLys contents also affected performance linearly (P < 0.001), but to a lesser degree; BWG decreased by 160 g when the dLys was reduced by 0.09% units, while the same reduction in dLys increased the FCR by 0.108 points. The inclusion of phytase alleviated the negative effects on feed intake (FI), BWG, and FCR. Phytase improved phosphorus digestibility and bone ash content according to a quadratic relationship. When phytase was added, ME negatively affected FI (r = -0.82, P < 0.001), whereas the dLys content was correlated with FCR (r = -0.80, P < 0.001). Supplementing phytase allowed the reduction of ME, dLys, and avP-Ca in the diet without affecting performance. The addition of phytase increased of ME, dLys, and avP by 0.20 MJ/kg, 0.04 and 0.18% units for 1,000 FTU/kg and 0.4 MJ/kg, 0.06 and 0.20% units for 2,000 FTU/kg.
Asunto(s)
6-Fitasa , Fósforo Dietético , Animales , Aminoácidos/metabolismo , Fósforo/metabolismo , Pollos , Suplementos Dietéticos , Fósforo Dietético/metabolismo , Calcificación Fisiológica , Dieta/veterinaria , Lisina/metabolismo , Aumento de Peso , Alimentación Animal/análisis , Digestión , Fenómenos Fisiológicos Nutricionales de los AnimalesRESUMEN
This experiment compared the effects of 2 chronic heat stress (HS) models, constant (coHS), and cyclic (cyHS), on broiler performance, carcass characteristics, and meat quality. A total of 720 male chicks from a Cobb 500 line were placed in 12 environmentally controlled chambers divided into 2 pens of 30 birds. Before the experimental HS models were applied, chamber temperatures were gradually decreased from 32°C at placement to 24°C on d 20. From 20 to 41 d, 4 chambers were set to 35°C (coHS), and 4 chambers were set to 35°C for 12 h and 24°C for the next 12 h (cyHS). Four thermoneutral chambers were maintained at 24°C with half of the birds pair-fed to equalize feed intake (FI) with coHS birds (TN-coPF) and half fed ad-libitum (TN-al). From 20 to 41 d, FI and BW gain (BWG) of cyHS, coHS and TN-coPF birds were decreased (P < 0.001), whereas feed conversion ratio (FCR) was increased (P < 0.001) for coHS and TN-coPF birds compared with TN-al birds. The overall BWG and FCR of coHS birds were lower (P < 0.001) than TN-coPF birds. Both HS models reduced (P < 0.001) carcass weight, pectoralis major yield, total breast meat yield, and increased (P < 0.001) wing yield relative to TN-al birds, with each of these measurements more impacted by coHS than by cyHS. Pair-fed birds had lower (P < 0.001) fat pad and a higher total breast meat yield than coHS birds. They also had the lowest (P < 0.001) pectoralis major ultimate pH and yellowness, and these parameters were lower (P < 0.001) for coHS birds than for TN-al birds. Both HS models reduced (P < 0.001) the incidence of woody breast and white striping. Thus, these data indicate that the detrimental effects of HS cannot be entirely explained by reduced FI and that HS per se affects metabolic pathways associated with muscle and lipid accretion in broilers.
Asunto(s)
Pollos , Respuesta al Choque Térmico , Carne , Alimentación Animal , Animales , Pollos/fisiología , Dieta/veterinaria , Calor , Masculino , Carne/normasRESUMEN
The nutritional composition of diets and the provision of exogenous enzymes play important roles in animal performance. Here, we evaluated the individual and combined impact of nutrients (metabolizable energy (ME), digestible lysine (dLys), available phosphorus and calcium (avP-Ca)) and exogenous multicarbohydrase and phytase complex (MCPC) enyzmes on the growth performance and feed efficiency of broiler chickens from 10 to 42â¯days (d) of age. Experimental diets were formulated in a Box-Behnken design to contain various levels of ME (11.89, 12.21, 12.54 or 13.06â¯MJ/kg), dLys (0.91%, 0.93%, 0.96% or 1.00%) and avP/Ca (0.12/0.47%, 0.21/0.58% or 0.33/0.68%). The effect of MCPC was expressed in terms of the extra nutrients released. The diets were formulated to have consistent substrate contents (i.e., arabinoxylan and phytate). Feed intake (FI), BW gain (BWG) and feed conversion ratio (FCR) were described via polynomial equations (R2â¯=â¯0.99, 0.98 and 0.81, respectively), with interconnections between variables (ME, dLys and avP-Ca). Available P-Ca was the most important factor affecting FI (quadratically), and BWG and FCR (linearly). Reducing the avP content from 0.33% to 0.12% in diets lacking MCPC resulted in 25% and 33% decreases in FI and BWG, respectively, and a 12% increase in FCR. The ME and dLys contents also linearly affected these performance parameters to a lesser degree; FI decreased by 400â¯g when the ME was reduced by 1.17â¯MJ/kg, and by 300â¯g following a 0.09% reduction of dLys, while the same reductions in ME and dLys decreased BWG by 120â¯g and 150â¯g, respectively. The inclusion of MCPC alleviated the reduction of FI, BWG and FCR by decreasing the avP-Ca. Thus, ME and dLys were the most important factors affecting BWG and FCR in broilers fed diets containing MCPC. When MCPC was added, ME negatively affected FI (râ¯=â¯-0.89, Pâ¯<â¯0.001), whereas the dLys content was correlated with BWG (râ¯=â¯0.74, Pâ¯<â¯0.001). Both ME and dLys affected FCR (râ¯=â¯-0.83 and -0.85, respectively). Supplementing MCPC allowed the reduction of ME, dLys and avP-Ca in the diet without affecting performance. Indeed, MCPC's effect promoted with the release of the following nutrients: 0.56â¯MJ ME/kg, 0.06% dLys, and 0.15% and 0.13% avP and Ca, respectively. The results indicate nutrient effect and interaction on performance and feed additive potential for nutrient release.
Asunto(s)
Pollos , Lisina , Alimentación Animal/análisis , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Dieta/veterinaria , Suplementos Dietéticos , FósforoRESUMEN
The objective of this ring test was to investigate the prececal phosphorus (P) digestibility of soybean meal (SBM) in broiler chickens using the trial protocol proposed by the World's Poultry Science Association. It was hypothesized that prececal P digestibility of SBM determined in the collaborating stations is similar. Three diets with different inclusion levels of SBM were mixed in a feed mill specialized in experimental diets and transported to 17 collaborating stations. Broiler chicks were raised on commercial starter diets according to station-specific management routine. Then they were fed the experimental diets for a minimum of 5 d before content of the posterior half of the ileum was collected. A minimum of 6 experimental replicates per diet was used in each station. All diets and digesta samples were analyzed in the same laboratory. Diet, station, and their interaction significantly affected (P < 0.05) the prececal digestibility values of P and calcium of the diets. The prececal P digestibility of SBM was determined by linear regression and varied among stations from 19 to 51%, with significant differences among stations. In a subset of 4 stations, the prececal disappearance of myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate)-P; InsP6-P) also was studied. The prececal InsP6-P disappearance correlated well with the prececal P digestibility. We hypothesized that factors influencing InsP6 hydrolysis were main contributors to the variation in prececal P digestibility among stations. These factors were probably related to the feeding and housing conditions (floor pens or cages) of the birds in the pre-experimental phase. Therefore, we suggest that the World's Poultry Science Association protocol for the determination of digestible P be should extended to the standardization of the pre-experimental period. We also suggest that comparisons of P digestibility measurements among studies are made only with great caution until the protocol is more refined.
Asunto(s)
Pollos/fisiología , Dieta/veterinaria , Digestión/fisiología , Fósforo Dietético/metabolismo , Alimentación Animal/análisis , Crianza de Animales Domésticos/métodos , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Calcio de la Dieta/metabolismo , Glycine maxRESUMEN
The DE values and digestible nutrients content of 6 diets were measured in 60-kg male growing pigs fed restricted amount of feed. Diets were prepared from 5 ingredients [wheat (Triticum aestivum), corn (Zea mays), barley (Hordeum vulgare), wheat bran, and soybean (Glycine max) meal; inclusion levels of ingredients were not correlated] with or without carbohydrose enzyme (Rovabio Excel AP; 3300 endo-ß-1,4-xylanase visco units and 300 endo-1,3(4)-ß-glucanase units/kg of feed; 150 g/t of feed) according to a 6 × 2 factorial arrangement; dietary NDF ranged from 10.6 to 20.1% of DM. Pigs (5 per treatment) were placed in metabolism cages that allowed total collections of feces and urine for 10 d after a 11-d adaptation. Samples of feed, urine, and feces were analyzed for GE, ash, and N. Digestibility of GE, N, and OM were calculated. The effects of diet and enzyme (Enz) were evaluated by ANOVA. In addition, the DE and digestible nutrient contents of ingredients were calculated by regression of nutritive values of diets on level of ingredient inclusions. Apparent total tract digestibility of OM, N, and GE of diets were associated with dietary NDF content (r = -0.97; P < 0.001) and were increased (P < 0.05) by Enz addition by 0.4, 1.6, and 0.5%-units (a difference between two percentage values) for OM, N, and GE digestibility, respectively. Improvement in DE value due to Enz averaged 0.09 MJ/kg DM (15.11 vs. 15.02 MJ/kg DM; P < 0.05). The ADG (891 vs. 850 g/d; P < 0.05) was also increased by Enz addition. The calculated DE content without Enz addition averaged 16.3, 16.4, 14.9, 10.5, and 17.2 MJ/kg DM for wheat, corn, barley, wheat bran, and soybean meal, respectively. The Enz addition increased the DE value of ingredients similarly, but the best response was observed for wheat (0.33 MJ/kg DM).
Asunto(s)
Alimentación Animal/análisis , Dieta/veterinaria , Digestión/fisiología , Complejos Multienzimáticos/farmacología , Porcinos/crecimiento & desarrollo , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Ingestión de Energía , Masculino , Complejos Multienzimáticos/administración & dosificación , Porcinos/fisiologíaRESUMEN
The present experiment was undertaken to study the interactions between dietary supplements of rumen-protected methionine (RPM) and intramuscular injections of folic acid and vitamin B(12), given from 3 wk before calving to 16 wk of lactation, on hepatic metabolism of lactating dairy cows. Sixty multiparous Holstein cows were assigned to 10 blocks of 6 cows each according to their previous milk production. Within each block, 3 cows were fed a diet calculated to supply Met as 1.83% of metabolizable protein, whereas the 3 other cows were fed the same diet supplemented with 18g of RPM calculated to provide Met as 2.23% of metabolizable protein. Within each level of Met, the cows received no vitamin supplement or weekly intramuscular injections of 160mg of folic acid alone or combined with 10mg of vitamin B(12). Liver biopsies were taken at 2, 4, 8, and 16 wk of lactation. Liver concentrations of folates and vitamin B(12) were increased by their respective supplements but this response to vitamin supplements was altered by methionine supply. Concentrations of total lipids and triglycerides increased in livers of cows fed RPM, whereas concentrations of cholesterol ester, cholesterol, diglycerides, phosphatidylethanolamine, and phosphatidylcholine were not affected. Folic acid, alone or combined with vitamin B(12), tended to increase the ratio of phosphatidylcholine to phosphatidylethanolamine. Gene expression of 5,10-methylene-tetrahydrofolate reductase, microsomal transfer protein, and phosphatidylethanolamine methyltransferase were higher in liver of cows fed RPM supplements. The relative mRNA abundance of 5,10-methylene-tetrahydrofolate reductase and methylmalonyl-CoA mutase were increased by the combined injections of folic acid and vitamin B(12), whereas those of methionine synthase and methionine synthase reductase were not affected by treatments. These results suggest that increasing supply of methyl groups, as preformed labile methyl groups or through methylneogenesis, affected the methylation cycle but had a limited effect on dairy cow performance. The observed effects of the combined supplement of folic acid and vitamin B(12) on lactational performance of dairy cows probably result from an improvement of energy metabolism during early lactation.
Asunto(s)
Dieta/veterinaria , Suplementos Dietéticos , Ácido Fólico/farmacología , Hígado/efectos de los fármacos , Metionina/metabolismo , Vitamina B 12/farmacología , Industria Lechera , Ácido Fólico/administración & dosificación , Regulación de la Expresión Génica/efectos de los fármacos , Inyecciones Intramusculares , Lípido A/metabolismo , Hígado/metabolismo , Distribución Aleatoria , Factores de Tiempo , Vitamina B 12/administración & dosificaciónRESUMEN
The present experiment was undertaken to determine if the effects of supplementary folic acid on lactational performance were caused by improved methylneogenesis and if the supply in vitamin B(12) could affect this metabolic pathway. In this eventuality, supplementary Met, a major source of preformed methyl groups, should reduce the requirements for these vitamins. Sixty multiparous Holstein cows were assigned to 10 blocks of 6 cows each according to their previous milk production. Within each block, 3 cows were fed a diet estimated to supply Met as 1.83% metabolizable protein and 3 cows were fed the same diet supplemented with 18 g of rumen-protected methionine (RPM) to supply Met as 2.23% of metabolizable protein. Within each level of Met, cows received no vitamin supplement or weekly intramuscular injections of 160 mg of folic acid alone or combined with 10 mg of vitamin B(12) from 3 wk before to 16 wk after calving. There was no treatment effect on dry matter intake during pre- and postcalving periods: 13.4 +/- 0.4 and 21.8 +/- 0.4 kg/d, respectively. Milk production was not affected by RPM supplementation. Folic acid and vitamin B(12) given together tended to increase milk production during the 16 wk of lactation. This effect was more pronounced during the first 4 wk of lactation: 37.5, 37.7, and 40.3 +/- 0.9 kg/d for cows receiving no vitamin supplement, folic acid alone, or folic acid combined with vitamin B(12), respectively. Milk fat yield was not affected by treatments. Lactose, crude protein, and total solid yields were greater, in early lactation, in cows injected with folic acid and vitamin B(12) together but this effect diminished as lactation progressed. Intramuscular injections of folic acid alone or combined with vitamin B(12) tended to decrease plasma concentrations of homocysteine from 5.51 microM with no vitamin supplement to 4.54 and 4.77 +/- 0.37 microM, respectively. Results of the present experiment suggest that the effects of the combined supplement of folic acid and vitamin B(12) on lactational performance of dairy cows were not due to an improvement in methyl groups supply, because RPM supplement, a source of preformed methyl groups, did not alter the cow responsiveness to vitamin supplements.
Asunto(s)
Bovinos/fisiología , Dieta/veterinaria , Ácido Fólico/farmacología , Lactancia/fisiología , Metionina/metabolismo , Vitamina B 12/farmacología , Complejo Vitamínico B/farmacología , Aminoácidos/sangre , Animales , Análisis Químico de la Sangre , Bovinos/metabolismo , Industria Lechera , Femenino , Ácido Fólico/administración & dosificación , Inyecciones Intramusculares , Distribución Aleatoria , Vitamina B 12/administración & dosificación , Complejo Vitamínico B/administración & dosificaciónRESUMEN
The present experiment was undertaken to determine the effects of dietary supplements of rumen-protected methionine and intramuscular injections of folic acid and vitamin B(12), given 3 wk before to 16 wk after calving, on glucose and methionine metabolism of lactating dairy cows. Twenty-four multiparous Holstein cows were assigned to 6 blocks of 4 cows each according to their previous milk production. Within each block, 2 cows were fed a diet estimated to supply methionine as 1.83% metabolizable protein, equivalent to 76% of methionine requirement, whereas the 2 other cows were fed the same diet supplemented daily with 18 g of rumen-protected methionine. Within each diet, the cows were administrated either no vitamin supplement or weekly intramuscular injections of 160 mg of folic acid plus 10 mg of vitamin B(12.) To investigate metabolic changes at 12 wk of lactation, glucose and methionine kinetics were measured by isotope dilution using infusions of 3[U-(13)C]glucose, [(13)C]NaHCO(3) and 3[1-(13)C,(2)H(3)] methionine. Milk and plasma concentrations of folic acid and vitamin B(12) increased with vitamin injections. Supplementary B-vitamins increased milk production from 34.7 to 38.9 +/- 1.0 kg/d and increased milk lactose, protein, and total solids yields. Whole-body glucose flux tended to increase with vitamin supplementation with a similar quantitative magnitude as the milk lactose yield increase. Vitamin supplementation increased methionine utilization for protein synthesis through increased protein turnover when methionine was deficient and through decreased methionine oxidation when rumen-protected methionine was fed. Vitamin supplementation decreased plasma concentrations of homocysteine independently of rumen-protected methionine feeding, although no effect of vitamin supplementation was measured on methionine remethylation, but this could be due to the limitation of the technique used. Therefore, the effects of these B-vitamins on lactation performance were not mainly explained by methionine economy because of a more efficient methylneogenesis but were rather related to increased glucose availability and changes in methionine metabolism.