Effect of the space allowance on growth of female hair lambs in raised-slatted floor cages

Background. The study of space allowance (m2) per animal is important, due in current production systems different group sizes are used throughout the year, without knowing their possible effects on daily weight gain and growth during the fattening period. Objective. The effect of space allowance on the growth of hair lambs in raised-slatted floor cages was determined. Methodology. Data from 527 daily weight gains (DWG) and weights adjusted at 60 (P60) days post-weaning of female lambs from commercial crossbreds between hair breeds were analyzed. The statistical model included fixed effects of space allowance (AL; 0.69, 0.64-0.60 and 0.56 m2/animal), year (A; 2012 and 2013), seasons of the year (EA; rainy and north) and the interaction on DWG and P60. The initial body weight was included as co-variate. Results. AL, A and interactions A × EA affected the dependent variables evaluated (P <0.05). AL larger (0.69 m2) and intermediate (0.64-0.60 m2) had similar growth (P >0.05); these groups, in turn, were the ones that obtained the highest DWG and P60 compared to smaller AL (0.56 m2). Higher growth of the female lambs was observed in the year 2012 compared to 2013. EA had no significant effect (P >0.05). Implications. The availability of the space allowance implies the quantity and quality, including the area occupied by the feeder and drinker. Conclusion. Under the conditions of the present study, AL should be adjusted between 0.69 and 0.60 m2/female lambs and that A and A × EA interaction can play an important role in animal growth.