Performance of broiler chicken submitted to a quantitative feed restriction program

The search for better zootechnical indexes such as feed conversion, daily weight gain, uniformity, and lower bird mortality has become a priority within the poultry industry. The use of food restriction programs has emerged as an alternative to improve these rates as well as to mitigate the effect of the increased cost of nutrition over the past few years. In this work, the feed conversion (FC), daily weight gain (DWG), uniformity, and mortality of male broilers submitted to two food restriction programs were evaluated; one program reduced food by 10% and the other by 20% in relation to the feeding program suggested by the Cobb500 strain. One hundred and eighty birds aged 10 days old were housed in 12 boxes for 30 days. Fifteen birds were placed in each box, and four replicates per treatment were designed: T1 (control group-feed intake as recommended by the Cobb500 strain), T2 (10% reduction), and T3 (20% reduction). There was no statistical difference in DWG, uniformity, or mortality between the treatment groups. As for FC, a statistical difference was observed with a gain of 100 g in T2 and 252 g in T3 in relation to T1. The results of this work demonstrate that food restriction programs can be used to improve FC in broiler flocks, without interfering with the DWG, uniformity, or mortality of birds.

Impact of an alternate feeding program on broiler breeder pullet behavior, performance, and plasma corticosterone

Broiler breeders are commonly feed restricted using some variation of skip-a-day feeding to prevent excessive body weight (BW) gain and poor flock uniformity that results in lower production levels. However, the level of feed restriction has increased leading to negative effects on broiler breeder welfare. Research needs to be conducted to evaluate alternative feeding programs to diminish the negative impact of restricted feeding on bird welfare. This research examined pullets that were fed soybean hulls (alternate day feeding, ATD) on the off day of a traditional skip-a-day feeding program in comparison to the standard skip-a-day program (SAD). The 2 dietary feeding treatments each had 3 replicate pens of 210 pullets each and were fed from wk 5 to 21 of age. Nitrogen-corrected true metabolizable energy and digestible amino acid coefficients of soybean hulls were determined. Body weight in the ATD feed program was significantly higher (P < 0.001) than the birds on the SAD feed program until 16 wk of age. Feed allocations for the SAD feeding program was increased at 11 wk of age to achieve similar BW prior to photo stimulation. The ATD feed program significantly improved BW uniformity of the birds for weeks 8, 12, 16, and 20. Hens fed on the SAD feed program had a lower mean egg production than the hens fed on the ATD program. There were significant differences on plasma corticosterone concentrations between the feeding days (24 or 48 h after feeding) in both feed programs. There was a shift in the behavior of the birds with significant differences in the feeding, foraging, and comfort behaviors between the feeding programs on the same feed day. Overall, feeding the ATD females soybean hulls on the off feed day improved the BW uniformity and egg production, but further research will be needed to determine potential differences in nutrient utilization or behavior of the pullets that positively impacted this flock performance.

Effects of qualitative and quantitative food restriction treatments on feeding motivational state and general activity level of growing broiler breeders

Growing broiler breeder chickens are fed restricted rations to limit body weight at sexual maturity. This experiment tested a proposal (Brouns, F., Edwards, S.A., English, P.R., 1994. Effect of dietary fibre and feeding system on activity and oral behaviour of group housed gilts. Appl. Anim. Behav. Sci. 39, 215-223.) that feeding motivation is reduced by using qualitative rather than quantitative food restriction, and it examined relationships among suppression of growth rate, feeding motivational state and general activity level. From 2 to 15 weeks of age, female broiler breeders were reared in six groups of 20, each with a different feeding treatment. The six treatments were: high and low levels of diet dilution (600-700 g/kg and 300-350 g/kg oat feed, ad libitum), appetite suppression (50-60 g/kg and 25-30 g/kg calcium propionate, ad libitum) and quantitative restriction (recommended daily ration and twice that amount). Birds were conditioned to an operant (PR1 schedule) feeding procedure with their respective treatment diets from 3 to 7 weeks, and this was used to measure feeding motivation in 12-min tests at three times of day (1000, 1300 and 1600 h) at 8, 10, 12 and 14 weeks. Proportions of time spent sitting were measured as an index of general inactivity in systematic observations at 9, 11, 13 and 15 weeks. Although the diet dilution and appetite suppression (qualitative) treatments did not limit growth rates as intended, they and the quantitative treatments produced a range of mean body weights to compare with feeding motivation whenever birds were tested. With body weight as a covariate, there were significant effects on numbers of operant responses in 12 min (the measure of feeding motivation) of weight, age, time of day and treatmentxtime interaction, but not treatment. Feeding motivation was positively correlated with suppression of growth rate, regardless of how that suppression was achieved. However, the experimental procedure required all test birds to be without food from 0900 or 0915 h, and motivation was lowest in the earliest (1000 h) test with qualitative but not quantitative treatments. Hence, there was some evidence that feeding motivation may be partially suppressed with qualitative food restriction; distinction can be made between short-term and longer-term feeding motivation. General activity level (inversely reflected by time spent sitting) was closely correlated positively with both suppression of growth rate and feeding motivation. As a fundamental relationship between feeding motivation and reduction of growth rate was not altered by using qualitative rather than quantitative food restriction, these results support an earlier conclusion (Savory, C.J., Hocking, P.M., Mann, J.S., Maxwell, M.H., 1996. Is broiler breeder welfare improved by using qualitative rather than quantitative food restriction to limit growth rate? Anim. Welfare 5, 105-127.) that broiler breeder welfare is not improved with qualitative restriction methods.

Equipment design for breeding flocks

Breeding stocks require specialized equipment and facilities that accommodate both sexes and their mating behaviors. Divergence in male and female requirements has occurred due to genetic selection, particularly in heavy meat stocks. Proper equipment design requires specific knowledge about the nutritional requirements, genetics, and behavior of the particular stock within the environment intended. Attention must be paid to the relationship between the rearing and breeding environments, because preferences and behavioral patterns develop at an early age. The "correct" breeding environment is highly dependent upon the growing environment. There is evidence that some undesirable behaviors and poor fertility may arise from inadequate rearing nutrition and that nutrition can influence the development of certain behaviors.

Is Broiler Breeder Welfare Improved by Using Qualitative Rather Than Quantitative Food Restriction to Limit Growth Rate?

Possible welfare benefits of qualitative rather than quantitative food restriction were investigated with growing female broiler breeder chickens (Ross 1). In Experiment 1, body-weight gains from 2 to 6 weeks of age were compared among different diet dilution, appetite suppression and low protein treatments, with free access to food at all times, to identify qualitative treatments causing weight gains similar to that recommended in the Ross 1 Parent Stock Management Manual. Based on these results, four diet dilution (400g kg−1 unmolassed sugar-beet pulp, 300 and 600g kg−1 oat hulls, 500g kg−1 softwood sawdust) and one appetite suppression (50g kg−1 calcium propionate) treatments were compared with two quantitative restriction (the recommended daily ration and twice that amount) and one ad libitum control treatments, from 2 to 10 weeks of age, in Experiment 2. As well as growth, food intake, excreta production and digestibility, measurements were also made of behaviour and blood indices of stress. Several conclusions were drawn. Different methods of qualitative food restriction can be used to control growth rate within desired limits. Problems with these methods include reduced uniformity in weight gain, increased excreta production and/or increased cost. Although they appear to suppress abnormal oral behaviours, they do not alter the increased general activity which is correlated with suppression of growth rate, and which may more accurately reflect associated hunger. Suppression of abnormal oral behaviours may only rarely correspond with reduction in blood indices of stress, and so cannot be taken to indicate improved welfare. Some of these methods can add to physiological stress. Finally, there was insufficient evidence of improved welfare, based on both behavioural and physiological criteria, to justify advocating the suitability of any of these methods for commercial use.

Hyperglycemia and non-enzymatic glycation of serum and tissue proteins in chickens

The objectives of these studies were to determine whether elevated plasma glucose concentrations in broiler breeder chickens (200-250 mg/dl) can result in the non-enzymatic attachment of glucose to serum proteins (fructosamine) and eventual cross-linking of tissue proteins (basement membrane thickness), and to investigate the effects of a factor that may influence this cross-linking process. In response to feeding the satiety factor calcium propionate (CaP, 1.7%), plasma glucose and fructosamine concentrations were increased (P < 0.05) from 1 to 9 weeks of age, whereas concentrations of plasma glucose and fructosamine in feed-restricted chicks were reduced for the first 7 weeks after hatch. In a second study, the age-related increase in kidney capillary basement membrane thickness was prevented (P < 0.05) by feeding the cross-linking inhibitor aminoguanidine (AG, 800 ppm) to 30-week-old broiler breeder hens for 34 weeks. The results from these studies suggest that concentrations of plasma glucose in chickens may, in fact, be exerting long-term detrimental effects on tissue proteins, which can be ameliorated by factors that limit the cross-linking reaction.

Broiler chick responses to anorectic agents: 1. Dietary acetic and propionic acids and the digestive system

The effects of various levels of acetic or propionic acid supplementation on feed intake and the gastrointestinal tract were studied in female broiler chicks. Voluntary feed intake and body weight gain decreased with the inclusion of the acids. Results indicate that acetic and propionic acids exert a similar anorectic effect on chicks fed diets differing in energy content. The inhibitory effect of these acids on voluntary feed intake could not be attributed to alterations in feed utilization, to differences in pancreatic alpha-amylase activity, or to differences in the acid-base balance. The increase in cecal capacity and volatile fatty acid (VFA) content is probably due to increased utilization of nonstarch polysaccharides at that site, the latter compensating for feed inhibition. This reflects a slight adaptive response of the cecum to anorectic agents.