Effect of graded nutrient density and exogenous enzymes on the profitability of laying hen production in South African conditions

Abstract

High energy feed ingredients are expensive and increase feed cost, thus lower energy diets may present an economic benefit. Precision nutrition and feed intake (FI) estimation can ensure nutritional requirements are met within the hen’s characteristic caloric intake and physical intake capacity. As dietary energy increases, the FI linearly decreases. However, diets should be nutritionally balanced as hens overconsume a high energy diet which results in a decrease in nutrient intake, poor feed efficiency, and high risk of prolapse due to excessive fat deposition. The aim of this study was to evaluate the relationship between graded energy levels and FI and the cost benefit in egg production of Hy-line Silver Brown laying hens at 40-weeks of age for a period of 70 days. The experimental design consisted of 8 treatments (TRT) with 16 replicate pens per TRT and 8 birds per replicate pen. Dietary TRT contained graded energy levels in ME (MJ/kg) as follows: TRT1, positive control (PC, 11.60), TRT2, negative control 1 (NC1, 11.46), TRT3, negative control 2 (NC2 = 50% NC1:50% NC3, 11.33), TRT4, negative control 3 (NC3, 11.20), TRT5 to TRT8 (TRT4 plus supplementation of various carbohydrate exogenous enzymes). The hens and feed allocation per pen were weighed at placement, and then on a weekly basis and mortality was recorded. Performance parameters included egg production, egg weight, feed conversion ratio (FCR) and FI. Results showed no differences in egg production and weight across TRTs. The FI for TRT1 was the lowest (P<0.05) compared to other TRT, while TRT4 had the lowest ME value and highest FI (P<0.05). A trend was seen in FI; as energy decreased FI linearly increased for TRTs 2 to 4. Treatment 5 had the highest FCR, while TRT2 had the lowest (P<0.05), and TRT1 was intermediate (P<0.05) to TRTs 2, 3 and 4. Treatments 3,4,5,7 and 8 all demonstrated a similar FI. The FCR for TRT3 and TRT4 were higher (P<0.05) than that of TRT1 and TRT2. Treatment 1 had the highest cost per ton, while TRT4 had the lowest. The feed cost per egg (FCE) decreased linearly as energy decreased, showing that cost per egg is directly related to energy density of feed. Treatment 1 had the highest (P<0.05) cost per egg, while TRT4 which had the lowest (P<0.05) ME/kg had the lowest (P<0.05) FCE compared to other TRTs. Treatment 2,3,5,6,7, and 8 had similar FCE. The feed cost per hen (FCH), income hen (IH), income minus feed cost (IF), and income from egg (IE) did not show significant differences across the experimental period. In conclusion, laying hens fed a diet with lower energy levels had improved FCR with no compromise in egg production and egg weight, implying that low energy levels can improve the profitability of hen production as long as feed is optimally balanced in nutrients. Additionally, no effects were seen on supplementation of exogenous enzymes on laying hen performance and economics.