Abstract:
27A Brown egg layers fed high density diets do not perform better in barn than in cages Y.L. Henuk and J.G. Dingle School of Animal Studies, University of Queensland, Gatton Qld 4345 ylh@sas.uq.edu.au The management manual for ISA Brown layers (IBL) indicates that daily protein intake should be 19.5 g/d (ISA 1996), and states that when the feed intake of barn hens increases the energy of the diet should stay constant, but the concentrations of nutrients in the diet should be reduced in proportion to the extra intake. In this 8 week trial, the diets fed to barn and cage hens had the same ME content (11.6 MJ/kg) but the CP contents of the Low, Medium and High diets were, 14.9, 17.0, and 19.5% respectively. The higher feed consumption of barn hens should enable optimum production with the cheapest (14.9 % CP) diet. The diets were formulated to be complete for vitamins and minerals but their adequacy was tested by adding (+) a vitamin and mineral premix (VMP). The 288 IBL used were 64 weeks old. Each treatment was given to two replicates of 12 hens/replicate. Although the diets without ( _ ) VMP were formulated to be complete by NRC (1994) standards, the results indicate that the vitamin and/or mineral contents were inadequate for optimum egg production for IBL. The diet containing 17 % CP (+) VMP was adequate for both barn and cage IBL, and there was no significant production advantage from a higher or lower CP diet. However, the cheaper 14.9 % CP diet would be more economic for barn hens which produce eggs that are sold for a higher price than those from caged hens. ISA (1996). ISABROWN Commercial Layers: Annex Management Guide. Isa, Lyon, France. National Research Council (1994). Nutrient Requirements of Poultry, 9th revised edition. National Academy Press, Washington D.C., USA. Table 1 Feed intakes and egg production by hens in cages or bar n given diets var ying in CP content, with or without a vitamin/mineral premix (VMP). Cages VMP Feed intake (g/bird/d) Protein intake (g/bird/d) ME intake (MJ/bird/d Feed efficiency (g/g) Egg production (%) Egg weight (g) Egg specific gravity (g/cc) Haugh units (_) (+) (_) (+) (_) (+) (_) (+) (_) (+) (_) (+) (_) (+) (_) (+) Yolk colour (Roche Fan) (_) (+) Low 105.5d 115.8 15.7 17.2 c f e Barn High 118.0 116.4 23.0 22.7 c c b bc Medium 115.2 114.7 19.6 19.5 c c d d Low 137.5a 133.7ab 20.5 19.9 d d Medium 122.0bc 128.0 20.7 21.7 b c c High 127.0b 127.1b 24.8 24.8 a a Pooled SE 2.0 0.36 1.22 1.34 2.37 2.35 68.4b 75.9 65.2 65.1 ab f f de de 1.34 1.33 2.31 2.20 73.1 78.4 68.3 66.6 de e 1.37 1.35 2.21 2.04 77.7 81.4 69.1 70.4 a b a e e 1.60 1.55 3.66 2.75 56.7 72.6 66.5 67.5 c ab ef cde a b 1.41 1.48 2.64 2.36 68.4 80.3 b a bc de 1.47 1.47 2.50 2.29 71.9 81.5 71.1 68.4 a a c cd de 0.24 0.07 ab ab c def ab ab 3.3 67.8cd 67.7cde 1.087 1.086 86.4 86.4 9.2 9.2 0.53 1.086 1.086 86.5 86.3 9.0 9.1 1.086 1.086 86.4 86.4 9.1 9.1 1.087 1.087 86.2 86.4 9.0 9.0 1.086 1.086 86.2 86.1 9.2 9.2 1.086 1.086 86.3 86.6 9.2 9.1 0.029 0.085 0.014 Within rows, means with different superscripts differ significantly (P<0.05) Recent Advances in Animal Nutrition in Australia, Volume 13 (2001)