A feeding study was conducted to compare the effects of litter material, dietary fibre and sex on growth performance, organ development, mucosal morphometry and gut microbial communities in broilers. Seven hundred twenty day old Cobb chicks were allocated to 24 floor pens in a 2 x 2 x 2 factorial design with 3 pens of 30 birds per replicate (3 pens of males and 3 pens of females). Factors were: litter material, paper or hardwood shavings; dietary fibre, low or high and sex. Diets consisted of wheat, soybean meal, meat meal, expeller canola meal, poultry fat, vitamin and minerals. Birds and feed were weighed on days 7, 21, and 35. Low fibre groups contained no oat hulls whereas high fibre groups contained 70 g/kg oat hulls. Birds grown on hardwood shavings had larger gizzards (P < 0.01) and a more favorable FCR (P < 0.03) than those grown on paper litter at 35 d. Dietary oat fibre was more beneficial in birds reared on paper litter than hardwood shavings as evidenced by significant fibre by litter interactions at 35 d for FCR (P < 0.02) and caecal C. perfringens counts (P < 0.01). Dietary oat fibre improved body weight at 7 d (P < 0.04), and lowered gizzard pH (P < 0.02) at 35 d. The results suggest that the combination of clean paper litter with high oat fibre diet may be beneficial in enhancing gut health in broilers.
In many areas, wood shavings are becoming scarce and expensive. Processed newspaper was found to be a suitable alternative to hard wood shavings as a litter material in broilers (Malone and Chaloupka, 1983). No significant effects on feed efficiency, litter caking or total disease condemnations were found between treatments. A broiler study conducted by Ali et al., (2009) found no differences in 42 d performance (P > 0.05) or gut microflora (P > 0.05) of birds reared on rice hulls, softwood sawdust, pine shavings, reused single batch litter, hardwood sawdust, shredded paper or chopped straw. Other investigators have concluded that litter material does not significantly impact broiler performance (Lien et al., 1992; Brake et al., 1993; Martinez and Gernat, 1995; Anisuzzaman and Chowdhury, 1996; Swain and Sundaram, 2000). Dietary fibre as soy or oat hulls was found to increase gizzard size and total tract nutrient retention in broilers suggesting a requirement for fibre in chick diets (Gonzalez-Alvarado et al., 2007). The current study was conducted to investigate the effects of litter type (paper or hardwood) and dietary oat hulls on gut physiology, broiler performance and gut microflora.
II. MATERIALS AND METHODS
Seven hundred twenty feather sexed Cobb 500 day old broiler chicks were randomly assigned to 24 sex separate pens in Ingham Enterprises environmentally control broiler research facility, 30 birds per floor pen. Birds were fed the diet compositions given in Table 1 in three phases. The ratio of protein, essential amino acids and minerals to metabolisable energy were constant between the low and high fibre diets for each phase. On day 35, four birds were randomly chosen from each pen for sample collection. The birds were euthanized by cervical dislocation as per UNE animal ethics protocol. Total body weight and various organ weights were measured and expressed as relative g/100g body weight. Contents of gizzard, ilea and caeca were collected for pH determination and microbial culture. The duodenum from a single bird per treatment was collected and fixed in 10% buffered formalin for histological examination after sectioning and staining with hematoxylin and eosin. A Leica DM LB microscope and Sony Exwave (SSC-DC83p) video camera was used to capture images and morphometric indices were determined using image processing software (VideoPro 32). Villus height and crypt depth were measured in 15 vertically, well-oriented, intact villi and crypts. Lactose-negative Enterobacteriaceae were counted on MacConkey agar (Oxoid, CM0115) after aerobic incubation at 39oC for 24 h. C. perfringens were counted on tryptosesulfite-cycloserine and Shahidi-Ferguson Perfringens agar base (Oxoid, CM0587) mixed with egg yolk emulsion (Oxoid, SR0047) and Perfringens (TSC) selective supplement (Oxoid, SR0088E) as described by Engberg et al., 2004. Bacterial numbers were expressed as log10 CFU/g digesta. All data were analyzed using the univariate general linear means procedure of SPSS (Ver 19.0.0).
Table 1. Diet composition
III. RESULTS AND DISCUSSION
A significant litter type by dietary fibre interaction was observed for body weight and FCR at 21 d (P < 0.01) and 35 d (P < 0.02). Performance was favored in birds fed diets containing oat hulls and reared on paper litter and low fibre diets reared on hardwood litter. The highest 35 d weight was achieved in birds fed high fibre diets on paper, while the best FCR was obtained feeding the low fibre diet to birds on hardwood shavings (see treatments means Table 2). Body weight was greater in birds fed oat hulls at 7 d (P < 0.04), and 21 d (921 vs. 903g; P < 0.01) and tended to be greater at 35 d (P < 0.07) as compared to the low dietary fibre treatments. As expected, males had higher body weights and better FCR than females at 21 and 35 d (P < 0.001).
Relative empty gizzard weight (g/100g BW) was 20% greater in birds reared on hardwood shavings than those reared on paper litter (P < 0.01) and 30% greater in birds fed oat hull diets relative to those fed low fibre diets (P < 0.01). Gizzard content pH was significantly lower in birds fed oat hull diets than those fed low fibre diets (P < 0.02). Litter type had no impact on gizzard pH (P > 0.27). Results appear in Table 3. Small intestinal crypt depth tended to be greater in birds grown on hardwood litter (339 vs. 281 µm; P < 0.08 while villus height was significantly greater in birds grown on paper litter (1707 vs. 1529 µm; P < 0.04.
There were significant litter by dietary fibre interactions for caecal C. perfringens counts (P < 0.01) and a tendency for an interaction for caecal Enterobacteriaceae counts (P < 0.08). Dietary oat hulls were more effective in reducing caecal C. perfringens and Enterobacteriaceae counts in birds reared on paper litter than on hardwood shavings (Table 3). Birds reared on hardwood litter had significantly higher counts of caecal Enterobacteriaceae than those grown on paper litter (P < 0.009). High dietary fibre tended to decrease Enterobacteriaceae numbers in caecal contents (P < 0.060).
Table 2. Bird performance on days 7 and 35
Results indicate a performance benefit for dietary oat hulls in young broilers especially those reared on paper litter. Litter type by dietary fibre interactions indicated performance benefits for dietary oat hulls in finishing broilers when reared on paper litter but not hardwood shavings. Higher counts of potentially pathogenic C. perfringens and Enterobacteriaceae (includes the genus Salmonella) were observed in the caecal contents of birds reared on hardwood litter compared to paper litter suggesting hardwood litter may be a potential source of inoculum. Dietary oat hull fibre was effective in reducing caecal C. perfringens and Enterobacteriaceae in birds reared on paper but not hardwood litter. This warrants further investigation.
Table 3. Gizzard weight and pH, caecal C. perfringens and Enterobacteriaceae counts
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This paper was presented at the 23rd Annual Australian Poultry Science Symposium, in Sidney, New South Wales from February 19-22, 2012. Engormix.com thanks the organizing committee and the authors for this contribution.