Interaction of pen environment and sex on growth performance and metabolite concentrations of Windsnyer pigs kept in a high stocking density M.V. Mkwanazi1, A.T Kanengoni 2 M. Chimonyo 1† 1Animal and Poultry Science, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, P Bag X01 Scottsville 3209, Pietermaritzburg, South Africa 2Agricultural Research Council-Animal Production Institute (Nutrition Building), Irene 0062, South Africa † Corresponding author, Email: velohv607@gmail.com, Phone: +27 73 4107 888, Background The Windsnyer is a short framed breed with long nose, razor back and has less mature weight than the fast growing improved breeds. The value of Windsyner pigs lie in their various attributes such as adaptability and tolerance to endemic diseases and parasites. They are adapted to survive under low planes of nutrition Reproduce at low dietary protein levels (Kanengoni et al., 2004). Windsnyer pigs also have low nutrient requirements for maintenance and growth. There are also policy disincentives that disapprove the production of indigenous pigs or encourage their replacement (Chimonyo & Dzama, 2007). No information is, however, available on their optimum stocking density Justification Determining the interaction between pen environment and sex on Windsyner pigs has a huge potential to enhance the contribution of these pigs to livelihoods. Objective To determine whether an interaction of pen enrichment and sex exist on growth performance and metabolite concentrations of Windsnyer pigs. Hypothesis It was hypothesized that the influence of pen enrichment on growth performance and metabolite concentrations in Windsnyer pigs depends on their sex. Materials and methods The trial was carried out at the Agricultural Research Council (ARC) Animal Production Institute at Irene, South Africa Growth rate, feed intake and feed: gain ratio were measured on a weekly basis. Blood sample was collected from each pig at the end of the trial (day 42) between 0800h and 1000h. The pigs were kept at a higher stocking density of 0.45 m2/pig. Enriched pens contained 2 litre bottles filled with stones and suspended at head level on ropes stretching across the pens. The PROC MIXED for repeated measures was used to analyse growth performance. PROC GLM procedure was used to analyse blood metabolite concentrations Results & Discussion To control the genetic erosion of Windsnyer pigs, identification of factors that promote their welfare and utilization need to be understood. The observed interaction between pen environment and sex on ADFI was unexpected, female pigs in the barren environment consumed more feed than females in enriched pens. It is likely that female pigs in enriched environment spent more of their time exploring the substrates than feeding. The observed interaction of pen environment and sex on glucose, was ascribed to female pigs in barren environment getting more glucose from the diet as a consequence of high ADFI. The observed pen environment and sex interaction on albumin, with enriched male pigs producing more albumin could suggest that enrichment enhances the ability of male pigs to increase their protein status. The observed interaction of pen environment and sex on BUN was attributed to enriched female pigs assimilating higher amount of nitrogen from the diet. Enriched females assimilated more protein levels than needed thus, excess protein was deaminated leading to high BUN. Table 1: Interaction of pen environment and sex on growth performance of Windsnyer pigs   ADFI (kg/day) ADG (kg/day) F: G ratio Enriched Barren Sex Male 1.12 ± 0.043a 1.10 ± 0.041a 0.42 ± 0.030b 0.45 ± 0.029b 0.25 ± 0.031a 0.39 ± 0.027b Female 1.13 ± 0.046a 1.29 ± 0.046b 0.30 ± 0.034a 0.27 ± 0.034a 0.28 ± 0.032a 0.38 ± 0.028b        Table 2: Least square means (± standard errors) of interaction between pen environment and sex on metabolite concentrations on Windsnyer pigs   Pen environment Significance Metabolite Enriched Barren S.E.M P S P × S Male Female GL (mg/dL) 70.3a 73.3a 72.2a 98.3b 4.61 NS * CHO (mg/dL) 70.0 70.5 68.2 74.2 3.97 ALB (g/dL) 3.79b† 3.22a 2.97a 3.07a 0.219 TP (g/dL) 7.19 7.25 7.18 6.52 0.62 BUN (mg/dL) 38.3a† 64.3b† 38.8a† 45.7a† 6.29 CA (mg/dL) 6.8 7.0 5.3 5.5 1.23 PHOS (mg/dL) 15.7† 12.9† 11.9† 12.3† 1.24 Conclusions Female Windsnyer in enriched pen environment perform better than those in barren environment. References Chimonyo, M, Bhebhe E, Dzama K, Halimani T.E and Kanengoni A (2005). Improving smallholder pig production for security and livelihood of the poor in Southern Africa. African Crop Science Conference Proceeding, 7:568- 573. Kanengoni, A. T, Dzama, K, Chimonyo, M, Kusina, J. and Maswaure S. M (2004). Growth performance and carcass traits of Large White, Mukota and their F1 crosses fed on graded levels of maize cobs. Animal Science, 78: 61–66. SAS 2009. SAS/STAT® Software Release 9.2. SAS Institute Inc., Cary, NC, USA. Acknowledgements Financial support from the University of Kwa- Zulu Natal, College Bursary for funding the project.. University of Kwa Zulu – Natal (Westville - Campus) for the analysis of blood samples.