Effect of different dietary ideal protein concentrations on broiler performance

Expression of lysine-mediated neuropeptide hormones controlling satiety and appetite in broiler chickens

Lysine is the second most limiting amino acid after methionine and is considered the most limiting amino acid for growth in poultry. Lysine requirement for broiler chickens has changed over the years. Leptin and adiponectin represent 2 adipokines that mediate metabolism by eliciting satiety effects whereas ghrelin peptide hormone influences appetite. We hypothesize that this affects growth performance of chicks. This study evaluates the effect of varying dietary lysine homeostasis on performance of broiler chickens through satiety- and appetite-mediating hormones. In 3 replications, 270 one-day-old chicks were reared for 8 wk feeding on diets comprising 0.85, 1.14, and 1.42% lysine during the starter period and 0.75, 1.00, and 1.25% lysine during the grower period. These concentrations of lysine represent 75% (low lysine), 100% (control), and 125% (high lysine) of National Research Council recommendation for broiler chickens. Feed and water were provided for ad libitum consumption. At 8 wk of age, liver, pancreas, brain, and hypothalamus tissues were collected from 18 birds randomly selected from each treatment, snap frozen in liquid nitrogen, and stored at -80°C until use. Total RNA was extracted, and cDNA was synthesized for quantitative real-time PCR assays. Low lysine concentration caused slow growth and high mortality. There was significant upregulation of ghrelin in the hypothalamus and pancreas, and leptin and adiponectin in the hypothalamus and liver, and downregulation of ghrelin in the intestines. At low lysine concentrations, adiponectin was not expressed in both pancreas and intestines. High lysine concentration exhibited increased growth, upregulation of ghrelin in the liver, and downregulation of ghrelin in the intestines, and both adiponectin and leptin in the liver. The expression of ghrelin was negatively correlated with the expression of adiponectin and leptin (P < 0.05) in the liver, hypothalamus, and pancreas. Expression of leptin was positively correlated with adiponectin in the hypothalamus and liver (P < 0.05), exhibiting satiety effects when the concentrations of lysine were low.

Response of two broiler strains to four feeding regimens under hot climate

In total, 392 male broilers were randomly distributed in a factorial arrangement of 2 × 4, with two commercial broiler strains (Arbor Acres (AA) and Hubbard (Hub)) and four (NRC, Degussa, CVB, and strain guides) different feeding regimens (FR), totaling eight treatments and seven replicates, with seven broilers in each one. The following parameters were evaluated: bodyweight gain (BWG), feed intake (FI), feed conversion ratio (FCR), carcass yield, meat quality, nutrient intake, and its correlation with BWG. Interaction strain type × FR was significant for BWG, FI, and FCR, with the AA broilers showing higher BWG and FI and lower FCR than the Hub broilers. There was no difference in BWG, FI, and FCR of the AA broilers regardless of FR they were on, but the Hub broilers had lower BWG when they were fed according to the Degussa and CVB regimens; BWG and FCR were negatively affected. During the starter phase, BWG of the AA broilers was significantly correlated with feed, metabolisable energy (ME), lysine, and sulfur amino acids (SAA) intake. However, BWG was correlated with feed and ME intake and feed intake from 1 to 31 and from 1 to 42 days of age, respectively. In the Hub chicks, ME and crude protein intake and lysine and SAA intake were inversely correlated with BWG from 1 to 31 days and from 1 to 42 days of age, respectively. There was no significant effect of FR on dressed carcass weight or relative gizzard, pancreas, and liver weights and on intestinal weight; however, abdominal fat and spleen differed significantly with FR. Strain type significantly affected the relative weight of the intestines. There was no significant effect of FR and/or strain type on meat moisture, crude protein, lipid and ash content, or pH, colour, meat juiciness and tenderness (meat softness). In conclusion, AA strain of broiler performed better than the Hub strain under the different FR in all the evaluated production phases, but neither FR nor strain type affected carcass characteristics.

Modeling as a research tool in poultry science

The World's Poultry Science Association (WPSA) is a long-established and unique organization that strives to advance knowledge and understanding of all aspects of poultry science and the poultry industry. Its 3 main aims are education, organization, and research. The WPSA Keynote Lecture, titled "Modeling as a research tool in poultry science," addresses 2 of these aims, namely, the value of modeling in research and education. The role of scientists is to put forward and then to test theories. These theories, or models, may be simple or highly complex, but they are aimed at improving our understanding of a system or the interaction between systems. In developing a model, the scientist must take into account existing knowledge, and in this process gaps in our knowledge of a system are identified. Useful ideas for research are generated in this way, and experiments may be designed specifically to address these issues. The resultant models become more accurate and more useful, and can be used in education and extension as a means of explaining many of the complex issues that arise in poultry science.

Feed formulations to reduce N excretion and ammonia emission from poultry manure

This summary focuses on reducing nitrogen (N) and ammonia emissions from poultry manure through the use of improved amino acid digestibilities and enzyme supplementation. Proper feed processing techniques, phase feeding, and the minimization of feed and water waste can contribute to additional minor reductions in these emissions. Reductions in environmental pollution can be achieved through improved diet formulation based on available nutrients in the ingredients, reducing crude protein (CP) levels and adding synthetic amino acids. Use of amino acid and CP digestibilities can reduce N excretion up to 40% and a 25% increase in N digestibility can be achieved with enzyme supplementation in broiler diets. Digestibilities can be measured by two methods: the excreta and ileal amino acid digestibilities. Both methods allow amino acid levels to be reduced by 10% or more. Enzyme supplementation decreases intestinal viscosity, improves metabolizable energy levels, and increases amino acid digestibilities. Many feed manufacturers still use total amino acid content to formulate feeds. To meet amino acid requirements, crystalline amino acids are needed. The use of feather, meat and bone meal must not be overestimated or underestimated and the limiting amino acids such as cystine, tryptophan, and threonine must be carefully analyzed.

Responses of male growing broilers to increasing levels of balanced protein offered as coarse mash or pellets of varying quality

Two experiments with 14- to 35-d-old male broilers were performed to investigate the interactions between increasing levels of balanced protein (BP; 9.7, 10.7, 11.7, and 12.7 g of digestible Lys/kg of feed) and physical feed form. In Experiment 1 diets were offered as coarse mash and pellets of either good or poor quality. Good pellet quality was characterized by high durability. In Experiment 2 diets were offered as good quality pellets or coarse mash. However, for the latter particle size, distribution either was kept constant with increasing BP or changed with increasing proportion of soybean meal. Feed intake generally decreased with increasing BP; however, feed intake was highest in good pellets fed to broilers and lowest in mash fed to birds. Although there was only a small response on weight gain in mash-fed birds, feed conversion improved substantially for all feed forms with increasing BP. Particle size distribution did not affect this effect. Highest weight gain was achieved with good pellets; to achieve similar performance with poor pellet quality, higher levels of BP were needed. Carcass evaluation suggested increasing breast meat yield and particularly decreasing fat accretion with increasing BP. Results of both experiments indicate that optimum dietary amino acid levels for growing broilers may vary among different physical feed forms.

Response of Male BUT Big 6 Turkeys to Varying Amino Acid Feeding Programs

Dietary protein is a major cost contributor in turkey nutrition. Therefore, a feeding trial with male BUT Big 6 turkeys to 154 d of age was conducted to examine how live performance and economics are affected when dietary amino acid levels are altered in different phases. Six dietary treatments were run with treatment 1 as the control in which balanced protein levels were according to recommendations during all 6 phases. Treatments 2 through 6 used combinations of balanced protein (based on lysine) that ranged from 90 to 120% of those used in treatment 1. The combinations for the 6 phases of feeding were 120, 120, 120, 120, 90, and 90% for treatment 2; 120, 120, 120, 100, 90, and 90% for treatment 3; 120, 120, 100, 100, 90, and 90% for treatment 4; 120, 120, 120, 120, 100, and 100% for treatment 5; and 90, 90, 90, 100, 100, and 100 for treatment 6. Final BW was highest in treatment 4 and lowest in treatment 2 (P < 0.05), whereas final BW were intermediate and statistically not different in treatments 1, 3, 5, and 6. Breast meat yield was highest in treatment 5 and lowest in treatments 2 and 3 (P < 0.05). Mortality seemed to be reduced in treatment 6 compared with treatments 2, 3, and 5 (P < 0.10). Performance data in combination with economic simulations suggested that the feeding regimens of treatments 4 or 6 might be alternative strategies to treatment 1 to improve overall profitability.

Effects of different dietary ideal protein levels on male and female broiler performance during different phases of life: single phase effects, carryover effects, and interactions between phases

Several experiments in which the dietary ideal protein (IP) levels were increased indicate that with current IP recommendations the maximum performance of broilers will not be achieved. However, available data of this IP-increment approach is scarce and, for the starter phase, entirely lacking. The objective of the present study, therefore, was to generate data regarding the effects in the starter phase and to test the impact of adequate vs. high IP levels in preceding phases on the response to IP increment in the phase under study. To evaluate this, an IP dose response in the starter phase and factorial arrangements combining adequate or high IP levels in starter and grower diets with low, adequate, or high IP levels in finisher diets were carried out with male and female broilers. Enhanced dietary IP levels in the starter diet increased BW gain in the starter phase and in the consecutive grower phase. Moreover, it was shown that a delay in BW gain due to suboptimal IP levels in the starter diet could only be partly compensated for in later phases of life. These results demonstrate the need for a reevaluation of IP levels used in practical starter diets. Feed conversion efficiency and BW gain responses to increased IP levels in the grower and finisher diets were less pronounced when high compared with adequate IP levels were fed in the preceding phase. This difference in response could not be detected statistically but was consistent between experiments and phases. Therefore, this phenomenon should not simply be neglected.