Evaluation of particle size and feed form on performance, carcass characteristics, nutrient digestibility, and gastrointestinal tract development of broilers at 39 d of age

The objective of this study was to evaluate combined effects of corn particle size and feed form on performance, carcass characteristics, nutrient digestibility, and gastrointestinal tract development of broilers from 1 to 39 d of age. A total of 1,800 days old, male Cobb 500 broilers were randomly assigned to 9 dietary treatments with 8 replicate pens (25 birds/pen). The experiment consisted of a factorial arrangement of 3 corn particle sizes (750, 1,150, and 1,550 μm) and 3 feed forms (mash, 3- and 4-mm pellets) provided from 1 to 39 d. Titanium dioxide (TiO2) was added as an indigestible marker (0.5%) during the finisher phase (27-39 d) to determine nutrient digestibility. Feed intake (FI), body weight (BW), and feed conversion ratio (FCR) were determined at 17, 27, and 39 d of age, with FCR adjusted for mortality. On d 40, 10 birds/pen were randomly selected and processed for meat yield determination. Data were analyzed as a 3×3 factorial (particle size x feed form) arrangement of treatments. Broilers fed 3- and 4-mm pellets had increased (P < 0.05) BW, FI, and lower FCR than broilers fed mash diets at 39 d of age. At 39 d of age, broilers fed diets with 750 µm corn particle size had heavier (P < 0.05) BW and increased FI than broilers fed diets with corn particle sizes of 1,150 and 1,550 µm. At 39 d of age FCR was unaffected by corn particle size. Heavier (P < 0.05) carcass and breast weights were observed for broilers fed 3-mm pellets. Broilers fed diets with corn particle size of 750 µm had heavier (P < 0.05) carcass and breast weight than broilers fed diets with 1,550 µm. Digestibility of nutrients was higher (P < 0.05) in pelleted diets, particularly when corn particle size was increased from 750 to 1,550 µm. Breast myopathies such as wooden breast (WB) and spaghetti meat (SM), were greater (P < 0.05) in broilers fed 3-mm pellets compared to mash diets. In conclusion, broilers fed 3- and 4-mm pelleted diets had greater nutrient digestibility and improved broiler performance compared to broilers fed mash diets.

Influence of barley inclusion method and protease supplementation on growth performance, nutrient utilisation, and gastrointestinal tract development in broiler starters

The influence of the method of barley inclusion (fine, coarse and whole barley) in a wheat-based diet and protease supplementation (0 and 0.20 g/kg) on growth performance, nutrient utilisation and gastrointestinal tract development of broilers (d 1 to 21) was evaluated in a 3 × 2 factorial arrangement. Whole barley (WB) grains were ground in a hammer mill to pass through the screen sizes of 2.5 and 8.0 mm to achieve fine (FB) and coarse (CB) barley particle sizes, respectively. A total of 288, one-day-old male broilers were allotted to 36 cages (6 cages/treatment; 8 birds/cage). There was no significant (P > 0.05) interaction between barley inclusion method and protease for any growth performance or nutrient utilisation parameters. Birds fed diets containing CB and WB showed higher (P < 0.05) weight gain, and digestibility of dry matter, nitrogen, calcium, gross energy, and ileal digestible energy compared to those fed FB diets. Compared to the birds fed FB diets, feed per gain was lower (P < 0.05) in birds fed diets made of WB. Fat digestibility of the birds fed CB was higher (P < 0.05) than those fed FB and WB birds. Compared to FB and CB diets, inclusion of WB resulted in heavier (P < 0.05) gizzards but reduced (P < 0.05) gizzard pH. Supplemental protease, however, had no effects (P > 0.05) on growth performance and nutrient utilisation, most likely due to the well balanced digestible amino acids and high inherent digestibility of protein in the basal diet, and/or the presence of exogenous carbohydrase and phytase. In conclusion, the present results showed that the inclusion of coarsely ground and whole barley in a wheat-based diet can enhance nutrient and energy utilisation and is beneficial to the growth performance of young broilers.

Feed acidification and steam-conditioning temperature influence nutrient utilization in broiler chickens fed wheat-based diets

Two experiments were conducted to examine the effects of conditioning temperature (CT) and the interactive influence of feed acidification (FA) and CT on the performance, coefficient of apparent ileal digestibility (CAID) of nitrogen (N), starch, fat calcium (Ca) and phosphorus (P), and AME in broilers. In both experiments, each treatment was randomly allocated to 6 cages (8 birds per cage) and fed from 1 to 21 D posthatch. In experiment 1, the effect of CT was evaluated using a wheat-based diet at 3 CT: unconditioned, conditioned at 60°C or 90°C. All the diets by-passed the pellet press and collected in mash form. Birds fed the diet conditioned at 90°C consumed more (P < 0.05) feed and tended (P = 0.087) to have higher feed per gain (F:G) than those fed the unconditioned diet but similar to those fed the diet conditioned at 60°C. A tendency was noted for CT to affect the CAID of N (P = 0.071) and starch (P = 0.093), with reduced digestibility values in the diet conditioned at 90°C. Conditioning at 90°C resulted in lower (P < 0.05) AME. In experiment 2, three inclusions of an acidifier (0.0, 7.0, and 10 g/kg) and 2 CT of 60°C and 90°C were evaluated in a 3 × 2 factorial arrangement of treatments using pelleted diets. Neither the main effects nor the interaction between acidifier addition and CT was significant for weight gain, feed intake, and F:G. The FA increased (P < 0.05) the CAID of N, fat, and P at both inclusion levels and of starch at 10 g/kg. Conditioning at 90°C reduced (P < 0.05) the CAID of starch, fat, and Ca, regardless of FA level. Overall, the present data showed that the application of high CT for broiler feed manufacture can impair nutrient utilization and, consequently the feed efficiency in broilers. Feed acidification imparts some benefits to nutrient digestibility in broilers fed pelleted wheat-based diets.

Influence of inclusion level of barley in wheat-based diets and supplementation of carbohydrase on growth performance, nutrient utilisation and gut morphometry in broiler starters

1. The influence of barley inclusion level and supplementation of a multi-component non-starch polysaccharide degrading enzyme on performance and nutrient utilisation in broilers was investigated. Normal-starch hulled barley was evaluated with five levels of inclusion (0, 141, 283, 424 and 565 g/kg) in a wheat-based diet and two levels of enzyme supplementation (0 and 150 g/tonne of feed; a 5 × 2 factorial arrangement of 10 dietary treatments). All diets were equivalent in metabolisable energy and digestible amino acid contents. A total of 400, one-d old male broilers (five cages/treatment; eight birds/cage) were used in the experiment.2. Regardless of enzyme supplementation, weight gain (WG) increased up to 283 g/kg of barley and was reduced afterwards (P < 0.01). Increasing levels of barley resulted in greater (P < 0.001) gain per feed (G/F). Enzyme addition increased WG (P < 0.05) and G/F (P < 0.001) at each barley inclusion level.3. Birds fed diets with 0 and 565 g/kg barley showed the lowest and highest (P < 0.001to 0.05) digestibility for all nutrients measured, respectively. Digestibility of all nutrients was improved by enzyme supplementation at each barley inclusion level (P < 0.05). The nitrogen-corrected apparent metabolisable energy improved with increasing inclusion of barley (P < 0.001) and supplemental enzyme (P < 0.01). Increasing inclusion of barley increased the relative weight of gizzard (P < 0.001) and reduced jejunal digesta viscosity (P < 0.001). Supplemental enzyme (P < 0.001) reduced digesta viscosity.4. The optimum inclusion level of barley, with respect to growth performance, was 283 g/kg of diet. Increasing barley inclusion improved nutrient and energy utilisation, possibly through lowered digesta viscosity and better function of the gizzard. Feed efficiency and nutrient and energy utilisation can benefit from carbohydrase supplementation in barley-based diets, regardless of barley inclusion level.

Avian Liver: The Forgotten Organ

Simple Summary

The liver is a multi-purpose organ, with involvement in bile secretion, and lipid, carbohydrate and protein metabolism, as well as a number of other metabolic functions. This organ can adapt easily to changes in feed and the environment. Being at the centre of a number of digestive, metabolic and productive activities, it is essential to have a better understanding of this organ and the factors affecting liver functionality.

Abstract

Despite having huge responsibilities in avian species, published reports on the influence of dietary factors and other possible constraints on the size, development and function of liver are limited. Consideration of the factors that could influence and alter liver function is therefore of critical relevance. In the current review, aspects of liver structure and function, and the influence of feed restriction, anti-nutritional factors, structural components and feed additives on liver are discussed. Effects of feed technology techniques such as thermal treatment and pelleting, feed particle size and whole grain feeding on the liver are also reviewed. A discussion of lipogenesis and lipid storage in poultry is presented to provide a better understanding and to differentiate the normal pathways of lipid metabolism from abnormal (i.e., disordered) pathways. The liver is the main site of fat synthesis in poultry, but under certain conditions, excessive fat can accumulate in the liver and cause problems. Factors contributing to the fatty liver syndrome are also examined.

Influence of pellet diameter and length on the quality of pellets and performance, nutrient utilisation and digestive tract development of broilers fed on wheat-based diets

1. The influence of pellet diameter and length on the quality of pellets and performance, nutrient utilisation and digestive tract development of broilers given wheat-based diets was examined from 10 to 42 d of age. The experimental design was a 2 × 2 factorial arrangement of treatments evaluating two pellet diameters (3 and 4.76 mm) and two pellet lengths (3 and 6 mm). From 0 to 9 d of age, all birds were offered a common starter diet pelleted with a 3-mm diameter die and 3-mm length. Broiler grower (d 10 to 21) and finisher (d 22 to 42) diets, based on wheat, were formulated and then subjected to the 4 different treatments. 2. In grower diets, increasing pellet diameter and pellet length reduced the gelatinised starch (GS) content of the diets. In finisher diets, GS content of 3-mm diameter pellets did not change with increasing pellet length but decreased in 4.76-mm diameter pellets. 3. In grower and finisher diets, increments in intact pellet weight, pellet durability index and pellet hardness with increasing pellet length were greater in 3-mm diameter pellets than those with 4.76-mm diameter. 4. Increasing pellet length from 3 to 6 mm increased apparent metabolisable energy values. Neither the interaction nor main effects were significant for the ileal digestibility of nitrogen and starch. 5. During the grower period (d 10 to 21), birds given pellets of 6-mm length had greater body-weight gain than those given 3-mm length pellets. Feeding 6-mm length pellets decreased feed per body-weight gain compared to 3-mm length pellets. During the finisher (d 22 to 42) and whole grow-out (d 10 to 42) periods, while different pellet lengths had no effect on feed per body-weight gain values at 3-mm pellet diameter, increasing the pellet length decreased feed per body-weight gain at 4.76-mm pellet diameter. 6. Increasing pellet diameter and pellet length reduced the relative length of duodenum. Birds given 3-mm diameter pellets had heavier proventriculus compared to those given 4.76-mm diameter pellets. 7. Overall, the data suggest that increasing the pellet length from 3 to 6 mm improved the body-weight gain and feed per body-weight gain during the grower period (d 10 to 21). While the positive effect on body-weight gain disappeared as the birds grew older, improvements in feed per body-weight gain were maintained over the finisher and whole grow-out periods only in 4.76-mm diameter pellets. Small diameter die holes and longer pellet lengths may be considered as potential manipulations to manufacture high-quality pellets under low conditioning temperatures.