Weight Gain Of Broiler Chickens Research Articles

Performance and Intestinal Mucosa Development of Broiler Chickens Fed Diets Containing Saccharomyces cerevisiae Cell Wall

Use of antibiotics as an additive in poultry diets to improve growth has been discussed in relation to bacterial resistance and the development of new products and management practices. This study was carried out to test the efficacy of a new substance (Saccharomyces cerevisiae cell walls, var. Calsberg- SCCW) obtained from the brewery industry, added (at 0.1 and 0.2%) to broiler chicken diets (based on corn and soybean meal), on performance and intestinal mucosa development. In Experiment 1 (carried out in litter-floor pens) the results revealed higher body weight gain for the total experimental period and higher villus height at 7 d of age for the birds fed 0.2% SCCW. In a field test using 44,000 broilers that received feed containing 0.2% SCCW, the results also showed higher body weight gain and better feed conversion for SCCW-supplemented birds. The present findings show that SCCW improved body weight gain in broiler chickens and that this effect can be attributed to the trophic effect of this product on the intestinal mucosa, because it increases villus height, particularly during the first 7 d of a chicken's life.

Nutritive value for broilers of meals derived from newly developed varieties of yellow-seeded canola

This study was conducted to determine the nutritive value of the meals derived from recently developed lines/varieties of canola. The samples included the yellow-seeded Brassica napus, B. juncea and B. rapa and the brown-seeded B. napus canola. Two commercial meals from yellow-seeded B. rapa and brown-seeded B. napus canola served as control samples. All samples were of canola quality and contained between 11.4 and 21.7 μmol g −1 of glucosinolate in the oil free meal. The evaluation involved chemical analyses of protein, amino acids, carbohydrates, dietary fibre, ash and ether extract, in vitro protein digestibility and true availability of energy (TME n) and amino acids. The overall feeding quality was evaluated in a 2-week growth trial with 4-day-old broiler chickens. There were no major differences among the meals with regard to amino acid content when expressed in g per 16 g N. The levels of amino acids reflected quantitative differences in the content of protein which for yellow-seeded B. napus and B. juncea and brown-seeded B. napus canola approached or exceeded 460 g kg −1 DM. Dietary fibre content varied from 271 to 352 g kg − 1 DM with the lowest value representing the yellow-seeded B. napus and the highest the commercial meal from brown-seeded B. napus canola. In vitro protein digestibility values showed minor differences among the samples. True digestibility of amino acids averaged 84.1% with only minor differences among the samples. True metabolizable energy content was highest in the yellow-seeded B. napus sample (9.71 MJ kg −1 DM). There were no differences in weight gain of broiler chickens fed the commercial or laboratory prepared B. rapa and the yellow- and brown-seeded B. napus meals. Chickens fed B. juncea meal showed significantly lower feed intake and body weight gain which appeared to be attributed to a relatively high content of aliphatic glucosinolates in this particular meal (i.e., 21.7 μmol/g DM). Birds fed the yellow-seeded B. napus canola showed the lowest feed to gain ratio which averaged 1.51 and differed significantly from that of 1.59 and 1.61 for the commercial yellow-seeded B. rapa and the laboratory prepared brown-seeded B. napus canola, respectively.

Performance and gastro-intestinal response of broiler chickens fed on cereal grain-based foods soaked in water

1. Two experiments were carried out to investigate the addition of 1.3 kg water per kg air-dry mash diets containing high proportions (600 to 700 g/kg) of ground cereal grains (wheat, barley or oats) on broiler performance and the structure and function of the gastro-intestinal tract. 2. Chicks at the age of 7 d were fed on the wheat-, barley- or oats-based diets in the dry or wet forms for 35 d. Food and water intakes were recorded daily while body weight was measured weekly. Two birds from each treatment were killed each week to measure gut size and the viscosity of gut contents. Tissue samples from various digestive segments were histo-morphologically examined to determine the thickness of tissue layers, size of tissue glands, villa heights, crypt depths and thickness of tunica muscularis . Crypt cell proliferation rate (CCPR) for each segment was also determined using a metaphase arrest technique. 3. The results from both experiments showed that wetting food significantly ( P <0.05) increased food intake, total water intake and body weight gain of broiler chickens. The body weight gains of birds were proportional to their food intakes so that the efficiency of food utilisation was similar for all treatments. Dry matter retention of food tended to increase in birds given wet food from 7 to 21 d but not thereafter, compared to the dry-fed birds. Although water intake from the water bottle was significantly ( P <0.05) reduced in birds given wet food, total water intakes from the water bottle plus that from food were significantly ( P <0.05) higher in the wet-fed birds than in the dry-fed birds. The ratio of total water to dry food intake was, however, similar in both feeding regimens. 4. The fresh empty weight of the gut was increased by wet-feeding while its relative weight to body weight and the length of gut was not affected by dietary treatments. Significantly greater development of the tissue glands in the proventriculus and gizzard was observed in the birds given wet food; this was associated with the reduced thickness of the muscular layer of these segments. An increase in villus height was also observed in duodenum, small intestine, caeca and colon of birds given wet food, compared to those given dry food. CCPR was significantly ( P <0.05) reduced by wet-feeding throughout the digestive tract. This was associated with a significant decrease in the mean viscosity of the gut contents and the concentration of volatile fatty acids (VFAs) in the caeca. 5. Wetting diets based on cereal grains caused a significant improvement in the performance of broiler chickens. The mechanism of the beneficial effects of wet feeding could be attributed to the decreased viscosity of gut contents; the greater development of the layer of villi in the digestive segments and the reduced CCPR in the crypts of the epithelium.

Propionic Acid and Calcium Propionate in Diets for Egg-Type Layers and Broiler Chicks

Abstract Oruwari, B.M. 1993. Propionic acid and calcium propionate in diets for egg-type layers and broiler chicks. J. Appl. Anim. Res., 3:73–81. Two experiments were conducted to determine the effects of low levels of supplemental propionic acid or calcium propionate on performance when these nutrients were included in diets for laying hens and broiler chickens. A supplementation of 1g calcium propionate/kg significantly increased egg production and 1g propionic acid/kg or 1g calcium propionate/kg significantly increased the body weight gain of broiler chickens at 4 weeks of age. Inclusion rates of propionic acid or calcium propionate up to 1 g/kg were safe and without any depressive effect on the performance of laying hens and broiler chickens in feeding trials of 28 and 4 weeks durations, respectively. The maximum tolerable level of propionate in diets for growing chicknes. Was 2g/kg. Calcium propionate appeared to be associated with antistress function in laying hens.

The Relationship between Male and Female Genotypes for Juvenile Body Weight and Weight Gain in Broiler Chickens

The objectives of this study were to examine the relationship between male and female genotypes for the juvenile body weight and weight gain in broiler chickens and to examine its effect on the response to selection.The data were collected from 1, 805 male and female chickens belonging to 317 sire groups of four breeding populations over four generations. The traits analysed were body weight at six and nine weeks of age and body weight gain from six to nine weeks of age.Genetic correlations of the same traits mentioned above between male and female sibs were estimated to be different among populations, which suggested that artificial selection for different breeding objectives might be responsible for differential genetic correlations among those populations.

Sire-Hatch Interaction Effects on Juvenile Body Weight and Weight Gain in Chickens

The objectives of this study were to evaluate the importance of sire-hatch interaction on the juvenile body weight and weight gain in broiler chickens and to check the biasness in heritability estimates of these traits due to the interaction.The data were collected from 4, 062 female chickens belonging to 281 sire groups of four breeding populations over 4 generations. The traits analysed were body weight at six and nine weeks of age and body weight gain from six to nine weeks of age. Statistical analyses were first made on the basis of within-flock and generation and then pooled over all flocks and generations. The statistical analysis employed was least squares of two-way mixed model with interaction in which hatches were assumed to be fixed and sire groups were assumed to be random.Statistically significant interactions were detected in six- and nine-week body weights and weight gain. The pooled estimates of the interactions explained 4.22%, 2.83% and 2.66% of the total phenotypic variations of those traits, respectively. These amounts of variability corresponded to 28.55%, 23.08% and 33.00% of the sire components, respectively. This suggests that the heritability estimates of those traits in broilers were overestimated.

The effects of dietary energy concentration on growth rate and conversion of energy to weight gain in broiler chickens

Synopsis Eight diets, their metabolisable energy (ME) concentrations ranging from 2.3 Mcal/kg to 3.6 Mcal/kg (9.6 to 14.1 MJ/kg) were fed to each of four pens of broilers in two trials. Food intake was inversely related to energy concentration but the ME required by each sex to reach a given live‐weight was quite similar. Birds on the diets with a medium energy concentration (about 3.1 Mcal/kg (13.0MJ/ kg)) required slightly less ME than those on other diets and generally reached the required live‐weight earlier than those on other diets. Birds in the first trial required less of any particular diet than their counterparts in the second trial, reflecting the lower ambient temperatures recorded during the latter trial. Mortality recorded from 14 d of each trial was generally lower for birds on the medium energy concentration diets and dressed carcass percentage higher than those on other diets. The results of the present study are in agreement with the recent recommendation (National Research Council, 1971...