The effect of feed additives, wheat variety and feed form on laying hen performance

Transcription

1 The effect of feed additives, wheat variety and feed form on laying hen performance M.D. SCOTT 1* and M.E.E. McCANN 1, 2 1 The Queen s University of Belfast, School of Agriculture and Food Science, 2 Agriculture, Food and Environmental Division, Agri-Food and Biosciences Institute, Newforge Lane, Belfast, BT9 5PX * Corresponding author: s @qub.ac.uk Feed additives are included in poultry rations to improve production efficiency. Wheat variety can affect the chemical composition and nutritive value of a diet and ultimately bird performance. The effect of feed form on hen performance is poorly established. The aim of this study was to assess the effect of different feed additives, wheat variety and feed form on laying hen performance. Two wheat varieties (Tanker and Riband) were evaluated with four additives in two feed forms (whole wheat and crumbs) resulting in 16 treatments. The diets were formulated to contain 600g/kg wheat. Additives included; Avizyme 1310 (0.375g/kg), Biomos (2g/kg) and an organic acid blend (4g/kg). The experiment utilised 96 individually caged hens over a period of eight weeks with six hens per treatment. Dry matter intake (DMI) and feed conversion ratio (FCR) were determined over the period. Egg production and weights were recorded on a daily basis. Birds were slaughtered and samples of the ileal digesta taken for in vivo viscosity measurement. Results were analysed using Analysis of Variance, Genstat 6. Wheat variety affected ileal in vivo viscosity (14.0 cps for Tanker and 8.5 cps for Riband). Whole wheat, in comparison to crumbs, increased gizzard weight (51.84g vs g) for both varieties and in vivo viscosity for Tanker-based diets (20.2cps vs. 7.8cps respectively). Egg production, total egg weight and feed efficiency were reduced (by 14.8, 18.6 and 12.6% respectively) for Tanker-based whole wheat diets. Egg production, egg weight and FCR were reduced with enzyme in comparison to the control and the other feed additives. An additive-feed form interaction was observed; +enzyme whole wheat resulted in a negative response whereas +enzyme crumbs had no effect (e.g. eggs produced ranged from 40.5 for +enzyme whole wheat to 55.1 for +enzyme crumbs over the 56 day period). Tanker was classified as hard with the 1B/1R gene whereas Riband was classified as soft without the 1B/1R gene. The varietal difference observed for viscosity may be attributed to the 1B/1R gene effect. Enzyme addition has been reported to reduce the negative effects of non-starch polysaccharides (NSP) and reduce viscosity. However, in the present study, enzyme addition reduced performance when added to whole-wheat diets, suggesting a ration particle-enzyme interaction, reducing enzyme effectiveness. The results of this study indicate that feed form can affect intake, with feed presented in the form of crumbs increasing intake. Keywords: Laying Hens; Additives; Wheat; Form

2 Introduction Prior to January 2006, antibiotic growth promoters in poultry rations were mainly employed to promote animal health status, uniformity of growth and production efficiency (Bedford, 2000). Alternatives to antibiotic growth promoters have been suggested and include enzymes, mannan oligosaccharides and organic acids. Within the UK, wheat accounts for 95% of the cereal constituent used in compound feeds for poultry and may contribute to as much as 700 g/kg of the diet for poultry. Wheat contains non-starch polysaccharides (NSP) at high levels, with the principal component, arabinoxylan (AX) resulting in high in-vivo viscosity within the gastro-intestinal tract of poultry contributing to an anti-nutritive effect. Exogenous xylanase can degrade AX by cleavage of the bonds within the xylan backbone reducing the molecular size and concentration, and thus reduces the ability to induce viscosity (Steenfeldt et al, 1998). Benefits of the effects of enzyme supplementation in laying hens are poorly established and inconsistent effects have been published (Lazaro et al, 2003). Enzyme addition within laying hen rations has been reported to increase the apparent digestibility of total NSP within wheat-based diets by 2.3% in comparison to unsupplemented diets, ultimately reducing viscosity within the gastrointestinal tract (Lazaro et al, 2003). Mathlouthi et al, (2003) reported a reduction in in-vivo viscosity of a wheat-based diet from 2.53 ml/g DM to 0.10 ml/g DM with enzyme inclusion. Reduced viscosity improves contact between nutrients and digestive enzymes, reduces retention time within the gut and increases feed consumption thereby improving growth, feed conversion ratio (FCR) and hen performance (Lazaro et al, 2003). In contrast, Bedford et al, (1996) suggested that the intestinal viscosity in birds fed wheat-based diets decreases with age, therefore, the efficiency of the xylanase may be reduced in laying hen rations, as laying hens are relatively mature birds. However, Mathlouthi et al, (2003) reported an increase in FCR of wheat-based laying hen rations from 1.97 to 1.89 g/g and in agreement, Lazaro et al, (2003) reported an improvement of 2.5% per dozen eggs with enzyme presence. Furthermore, egg production has been reported to increase by 2.6% (Lazaro et al, 2003) and 4.9% (Graham, 1991) with enzyme inclusion but Rafuse et al, (2004) and Roberts et al (1993) reported no effect with enzyme supplementation. Improvements in eggshell quality have also been observed with respect to shell breakage strength, shell weight and yolk colour (Geraert et al, 2003) but reductions in internal egg quality were reported (Roberts et al, 1999). Shell strength was reported to increase from 32.6 to 35.1 with enzyme as did shell weight with values ranging from 5.90g to 6.02g (Roberts et al, 1999). In contrast, no significant effects of enzyme supplementation have been reported with respect to egg quality; egg weight, yolk quality, albumen quality, shell weight, shell index and shell thickness (Geraert et al, 2003). Other studies have observed decreases in mortality (11.3 vs. 4.0 %), osteoporosis (5.3 vs. 0.7 %), litter problems, within flock variation and improvements in bird health with enzyme supplementation (Graham, 1991). Mannan oligosaccharides have many general advantages with respect to poultry performance and health. Biomos is a synthetic mannan-oligosaccharide with a receptor-annalog mechanism (Iji and Tivey, 1998) which binds competitively to bacteria, reducing colonisation and infection. The effect of mannan-oligosaccharide/biomos on broiler chickens has been well established but little research has been conducted with respect to laying hens. Inclusion of mannan-oligosaccharides in laying hen rations has been reported to improve egg-laying rate by 1.36% (Wang Li et al, 2002) and 2.47% (Vranesic et al, 2003). An enhanced FCR was also observed by Wang Li et al, (2002) with an inclusion rate of 0.3% resulting in an increase of 10.71%. Furthermore, feed intake was reported to be reduced by 3.98% (Vranesic et al, 2003) indicating mannan-oligosaccharide improves the feed efficiency of the diet. However, addition of mannan-oligosaccharide had no obvious effects on eggshell thickness, eggshell weight or the percentage of broken and soft-shelled eggs (Wang Li et al, 2002). Variety can affect the chemical composition and nutritive value of wheat for broilers but the effect for laying hens is less well established. Scott and Mc Cann, (2005a), found that variety significantly affected the apparent metabolisable energy (AME) and ileal digestibility in the laying hen but the effects were not consistent. A variety-enzyme interaction was observed with respect to egg quality. Significant differences occurred in eggs produced, dry matter intake (DMI) and yolk diameter, although findings were inconsistent. Due to the inconsistency of the results, further investigation into the effect of variety on laying hen performance and feed digestibility is required.

3 The effect of feed form on laying hen performance is poorly established, and inconsistent results have been published. Scott and Mc Cann, (2005b), found that feeding whole wheat cereal plus balancer significantly increased egg production, total egg weight, average egg weight and DMI, in comparison to mash, crumbs or pellets. With respect to egg production, offering feed as crumbs produced better performance than mash and pellets but resulted in a poor feed conversion ratio (FCR). The overall aim of this experiment was to investigate the effect of different feed additives, wheat variety and feed form on laying hen performance and establish the variables that achieve the optimum egg quality and hen performance. Materials and methods Sixteen experimental treatments were formulated to contain 600g/kg of two wheat varieties (Tanker and Riband) with or without a feed additive (control, enzyme, mannan-oligosaccharide, and organic acid) in two feed forms (whole wheat or crumbs) and with a metabolisable energy (ME) value of MJ/kg. Additives included were; Avizyme 1310 (0.375 g/kg), Biomos (2g/kg) and an organic acid blend incorporating fumaric, lactic and proprionic acids (4g/kg). The treatments were offered to groups of six individually caged birds over a period of eight weeks. 96 laying hens (35 weeks of age; Hy-Line; brown eggs) were individually caged and randomly assigned into a 2*4*2 factorial experiment, 6 birds per treatment. Hens were initially weighed, divided into weight blocks and within each block randomised into experimental treatments. Each cage was equipped with a feeder and two nipple drinkers. Dietary rations and water were supplied adlibitum. Light was provided for 16 hours per day and the room temperature was maintained at 23± 3ºC throughout. The experiment was conducted over eight weeks. Feed consumption was determined at weekly intervals. At the end of the eight weeks the birds were killed by dislocation of the spinal cord and dissected. In-vivo viscosity of jejunum contents and empty gizzard weights were recorded for each bird. Total number of eggs produced including cracked, broken, soft, double yolked and abnormal were recorded daily. Each individual egg was weighed and recorded on a daily basis. Eggs for egg quality analysis were collected at the end of week 3 and 6. Egg quality measurements recorded included; specific gravity, shell thickness, haugh unit, yolk diameter and yolk height. Results were analysed using Analysis of Variance, Genstat 6. Results and Discussion Wheat variety significantly (P<0.05) affected ileal in-vivo viscosity (14.0 cps for Tanker and 8.5 cps for Riband) and shell thickness (0.37mm for Tanker and 0.39mm for Riband) (Table 1). Wheat characteristics can vary between varieties with respect to 1B/1R gene presence and endosperm texture. In this study, the wheat variety, Tanker, was classified as hard and contained the 1B/1R gene, whereas Riband was classified as soft and did not contain the 1B/1R gene. The varietal difference observed for in-vivo viscosity can be attributed to the 1B/1R gene effect as the 1B/1R gene presence has been correlated to an increase in the soluble fibre fraction. Furthermore, George and Mc Cracken, (2001) reported an increase in the in-vivo viscosity caused by the 1B/1R translocation. The reduced shell thickness resulting from the inclusion of Tanker may be attributed to the reduced productive energy available. A hard endosperm requires extensive grinding in comparison to a soft endosperm resulting in an increase in the energy expended, reducing the productive energy available (Rose, 1996). Whole wheat feeding in comparison to crumbs significantly increased gizzard weight (51.84g vs g). Gizzard activity increases with the inclusion of whole wheat due to enhanced mechanical stimulation resulting in muscular development and increased weight (Engberg et al, 2004). Gizzard weight and ileal viscosity increased with Tanker- whole wheat with values ranging from to g and 5.2 to 20.2 cps respectively. Gizzard weight increased due to the combination of the mechanical stimulation resulting from whole wheat inclusion and the hard endosperm texture of Tanker. The increase in ileal viscosity may be due to the 1B/1R gene presence within Tanker as the 1B/1R gene is attributed to the increase in soluble fibres, ultimately increasing the in-vivo viscosity.

4 Egg production, total egg weight and shell thickness were reduced with the Tanker- whole-wheat diets in comparison to the others evaluated. The combination of the hard endosperm texture of Tanker and the whole wheat form requires additional grinding within the gizzard, increasing the energy expended and reducing the productive energy available for egg production, total egg weight and shell thickness. Feed efficiency may be reduced due to the increased viscosity and energy required for extensive grinding. Egg production, total egg weight and feed efficiency were reduced (by 14.8, 18.6 and 12.6% respectively) for Tanker-based whole wheat diets. Crumbed diets are dense, palatable and easily consumed leading to an increase in feed consumption. Consumption of crumbs tends to expend less energy than consumption of whole wheat as exploratory pecks during whole-wheat consumption increases the energy expended, ultimately explaining the improvement in FCR with the provision of crumbs. Improvement in egg production, total egg weight, average egg weight, shell thickness and shell surface area may be explained by the increased feed consumption (with the resulting increase in protein and energy consumption) of crumbs in comparison to the whole wheat Tanker-based rations (Pepper et al, 1967). A variety-additive interaction was observed; Tanker plus enzyme significantly reduced hen performance in comparison to the other treatments with respect to FCR (ranging from 1.78 to 2.28 kg feed: kg egg), eggs produced (ranging from to 51.88) and total egg weight (ranging from 2623 to 3337g). The negative effect of the interaction observed may be a result of the combination of the excessive grinding required to manipulate Tanker and the lack of a significant positive effect of enzyme, resulting in a reduction in the productive energy reducing the FCR and hen performance. Laying hens are mature and as in vivo viscosity falls with age, enzyme addition may have less effect compared to younger birds (Bedford et al, 1996). However, an additive-feed form interaction was observed (Table 2). Enzyme addition to the whole-wheat ration reduced egg production (ranging from 40.5 to 55.1), total egg weight (range from 2489g to 3507g), shell thickness (range from 0.33 to 0.41 mm) and feed efficiency (2.32 compared to 1.76 kg feed: kg egg). Enzyme addition to the wholewheat ration resulted in a negative response whereas enzyme addition to the crumbed ration had no significant effect in comparison to the other feed additives and control. Enzyme addition reduced performance when added to whole-wheat diets, which may indicate that there was a reduced ration particle-enzyme interaction due to the feed form, which reduced the effectiveness of the enzyme. The combination of excessive grinding required for the whole-wheat feed form, lack of benefit from the enzyme supplementation and the possibility of a particle-enzyme interaction reduction may have reduced hen performance and the feed conversion efficiency. Wheat variety-feed form-feed additive interaction generated several significant effects on hen performance. Tanker-whole wheat-enzyme interaction significantly reduced egg production, total egg weight, shell thickness, shell weight and shell fracture force with ranges; to 55.56, 1811g to 3623g, 0.26mm to 0.36mm, 48.97g to 59.86g and 3078 to 4167 respectively. Again, te combination of the hard endosperm, the1b/1r gene presence within the Tanker variety, the increased grinding within the gizzard due to the whole wheat, the lack of benefit arising from the enzyme supplementation and the possibility of a particle-enzyme interaction problem may explain the reduction in hen performance. In conclusion, laying hen performance tended to improve with the inclusion of soft wheat without the presence of the 1B/1R gene. The additives studied resulted in similar performance with the exception of enzyme, which significantly reduced performance. Feed form can significantly affect performance. The hard endosperm whole wheat reduced performance whereas the inclusion of soft whole wheat did not significantly affect performance. Whole-wheat inclusion plus enzyme significantly reduced performance.

5 Table 1. Effect of the variety-feed form interaction on laying hen performance Tanker Riband Variety Feed Form Variety-Feed Form Whole Wheat Crumbs Whole Wheat Crumb SEM P SEM P SEM P Gizzard Wt (g) c a b a NS < <0.05 Ileal Viscosity (cps) b 7.80 a 11.8 a 5.20 a 2.75 < < <0.001 Eggs Produced/56 days a b b b NS < <0.001 Total Egg Wt (g/56 days) 2809 a 3463 b 3255 b 3276 b 74.2 NS < <0.001 FCR (kg feed: kg egg) 2.07 b 1.77 a 1.81 a 1.84 a NS < <0.05 Shell Thickness (mm) 0.34 a 0.39 b 0.38 b 0.39 b < < <0.05 Yolk Height (mm) b a b b NS NS <0.05 Yolk Index 6.86 c 6.37 a 6.47 ab 6.73 ab NS NS <0.05 Haugh Unit 85.7 b 77.7 a 79.4 ab 84.0 ab 2.58 NS 5.10 NS 2.58 <0.05 a, b and c superscripts within a row without a common superscript are significantly different. Table 2. Effect of the additive-feed form interaction on laying hen performance Whole Wheat Crumbs Additive Additive-Feed Form Ctrl Enzyme Biomos Organic Acid Ctrl Enzyme Biomos Organic Acid SEM P SEM P Gizzard Wt (g) NS NS Ileal Viscosity (cps) NS 3.88 NS Eggs Produced/56 days bc a b bc b c bc bc < <0.001 Total Egg Wt (g/56days) 3226 bcd 2489 a 3126 b 3286 bcd 3131 bc 3428 cd 3507 d 3412 bcd 74.9 < <0.001 FCR (kg feed: kg egg) 1.76 a 2.32 b 1.86 a 1.83 a 1.92 a 1.80 a 1.77 a 1.74 a < <0.001 Shell Thickness (mm) b a b bc bc c bc bc NS <0.05 Yolk Height(mm) bc ab bc bc a bc c bc < <0.05 Yolk Index NS NS Haugh Unit NS 3.65 NS a, b and c superscripts within a row without a common superscript are significantly different

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