The response of broiler breeder hens to dietary balanced protein

Two basal feeds (118 and 175 g protein/kg) with similar balanced amino acid mixtures were appropriately blended to produce six experimental diets differing in protein. These were fed for six weeks to 180 broiler breeder hens (Ross 308) housed in individual cages from 26 w of age. A 13 h photoperiod was applied. Half the birds were restricted to 160 g of feed/d, whilst the others were fed ad libitum. The treatments were randomly allocated within six blocks. At the end of the six-week period the mean voluntary intake of the ad libitum-fed birds was 169 g/d whereas the intake of hens on feed restriction was 155 g/d. In spite of the range of protein intakes from 18.5 and 28.8 g/bird, no differences were observed in rate of laying between the two feeding strategies or dietary protein levels, nor were there differences in the proportions of yolk or albumen between these treatments. Egg weight, egg output and weight gain increased with protein intake as did energy retention (kJ/d) whereas heat output (kJ/d) decreased as protein intake increased. Even though dietary protein intake had no effect on rate of lay, the resultant decrease in heat output at high protein intakes suggests that this might be a useful strategy to consider for overcoming mild heat stress.Keywords: Ad libitum feeding, heat production, energy retention, egg compositio

Biological performance and gastrointestinal development of broiler chicks fed diets varying in energy : protein ratio

(South African J of Animal Science, 2000, 30, Supplement 1: 136-137

Growth and laying performance of medium-type pullets subjected to Quantitative and qualitative food restriction

No Abstrac

Diet selection priorities in growing pigs offered a choice of feeds

Two experiments were conducted to test whether young pigs are capable of discriminating against a feed based on its nutrient balance (or protein value) and/or the presence or absence of anti-nutritional factors, and whether there is an order of preference. In each experiment 48 Large White x Landrace female pigs weighing 16.5±1.50 kg were randomly allocated to one of either 12 dietary treatments (Experiment 1) or 14 dietary treatments (Experiment 2) and kept on the treatment diets for four weeks. In Experiment 1 there were four single feed control treatments, four two-feed choice treatments and four three-feed treatments. The choices were between soyabean oilcake vs. cottonseed oilcake as the main dietary protein source, and between diets that have a higher (balanced) versus lower (unbalanced) proportion of amino acids compared with the balance of amino acids in ideal protein. Experiment 2 had similar choices to Experiment 1, but also included treatments with 1% added tannin. The results showed that when young pigs were given a choice of diets their preference was firstly against potentially harmful substances in the feed (e.g. tannin) or an anti-nutritive factor (e.g. cottonseed oilcake), and then for better-balanced or higher protein-value feeds. South African Journal of Animal Science Vol.32(2) 2002: 136-14

Ruminal degradability and intestinal digestion of eight plant protein supplements used in ruminant diets

(South African J of Animal Science, 2000, 30, Supplement 1: 51-52

Utilization of protein from opaque -2 Maize by chicken and rat

No Abstrac

Performance of broiler chickens fed South African sorghum-based diets with xylanase

Two experiments were conducted to determine the influence of sorghum variety and xylanase on performance of broiler chickens. In Experiment 1A, a total of 240 day-old Ross broiler chickens were assigned to a 2 (sex) × 3 (sorghum variety) × 2 (with or without xylanase) factorial arrangement in a completely randomized design with 20 chickens per treatment. Gross performance measurements were assessed at 7, 14, and 21 days of age. Carcass yield and visceral organ weights were measured at day 21. In Experiment 1B, a total of 108 female Ross 308 broiler chickens were randomly assigned to a 3 (sorghum variety) × 2 (with or without xylanase) factorial arrangement in a completely randomized design with 6 treatments replicated 6 times. On day 25, all birds were euthanazed by intravenous injection of sodium pentobarbitone and digesta contents from the distal ileum were collected to determine the nutrient digestibility. Broiler chickens offered sorghum variety Pan8816 supplemented with xylanase had higher feed intake, weight gain, and similar feed conversion ratio at 1 - 7 days of age. Breast meat of broiler chickens was not affected by variety or xylanase. The small intestine was heavier in the Pan8625 and Pan8816 groups with xylanase than in the similar Pan8906 group. Enzyme inclusion increased the crude protein digestibility. When xylanase was included in all sorghum varieties, numerically, starch digestibility tended to improve. Sorghum variety affected the growth performance of broiler chickens. Furthermore, nutrient digestibility was affected by the differences in variety.Keywords: Digestibility, tannin, poultry, visceral organs, xylanas

The response of weaned piglets to dietary valine and leucine

Valine (Val) is considered to be the fifth-limiting amino acid in a maize–soyabean meal diet for pigs. Excess leucine (Leu) levels often occur in commercial diets, which may attenuate the effect of Val deficiency because of an increased oxidation of Val. The objective of the present experiment was to determine the effect of increasing concentrations of Leu on the response of young piglets to dietary Val. In all, 75 Large White×Landrace entire male pigs, 44 days of age and with a mean starting weight of 13.5 kg, were used. Three of these were sacrificed at the start to determine their mean initial chemical composition. A summit feed first limiting in Val was serially diluted with a non-protein diluent to produce a series of five digestible Val concentrations of 11.9, 10.1, 8.3, 6.6 and 4.8 g/kg, with a sixth treatment being added to test that the feeds were limiting in Val. Three identical Val series, each with six levels of Val, were supplemented with increasing amounts of Leu (23, 45 and 67 g/kg), thus 18 treatments in total. All pigs were killed at the end of the trial after 18 days for analysis of water, protein, lipid and ash in the carcass. The levels of Val and Leu and their interaction significantly influenced all the measurements taken in the trial. Daily gain in liveweight, water and protein, and feed conversion efficiency all increased with dietary Val content, whereas feed intake decreased as both Val and Leu contents increased. The deleterious effect of increased Leu on feed intake and growth was more marked at lower levels of Val. Supplementing the feed with the lowest Val content with additional Val largely overcame the effect of excess Leu. The efficiency of utilisation of Val for protein growth was unaffected by the level of Leu in the feed, the primary response to excess Leu being a reduction in feed intake. An intake of around 9 g Val/day yielded maximal protein growth during the period from 44 to 62 days of age in pigs of the genotype used in this trial.The South African Pork Producers Organisationhttp://journals.cambridge.org/action/displayJournal?jid=ANM2018-02-27hb2017Animal and Wildlife Science