The ability of sheep to reach for food through tombstone barriers, as affected by position of food, body weight and body dimensions

Abstract

Two studies were undertaken to provide information on the ability of sheep to reach for food similar to that for cattle fed through tombstone barriers. In the first study twenty castrate and twenty non-pregnant, that for cattle fed through tombstone barriers. In the first study twenty castrate and twenty non-pregnant, female unshorn Suffolk x Mule sheep (23 - 89 kg live weight) were trained to reach, through a vertical tombstone barrier for concentrate meal placed on a horizontal platform attached to the barrier. The barrier allowed the neck to pass through, but not the shoulders. It was hypothesised that horizontal reach forwards (F. distance from mid-point of barrier to uneaten meal) and sideways (S. distance sideways from mid-point of barrier to uneaten meal adjacent to barrier) would be a function of height of platform above the floor and body size (M). Because of size seventeen sheep (mean 34.6 kg) were unable to reach the meal when the platform height was 75 cm. Mean (s. e.) values for F at platform heights 0. 25. 50 and 75 cm were 43.91.03. 9.40.91. 47. 00. 96 and 27.01.27 cm respectively. Values for S were smaller but followed a similar pattern (36.61.10. 43.50.80. 41.00. 79 and 22.91.78 cm). Linear regression showed that F or S could be predicted from M (R² >0.5) or a combination of M and withers height (R²>0. 7) when platform heights were 25. 50 or 75 cm. Reach at 0 cm platform height was not related to body weight or linear dimensions. In the second study with unshorn Suffolk x Mule sheep ten castrates and ten non-pregnant females (23 - 97 kg live weight) were trained to reach through the tombstone barrier for concentrate pellets glued' using molasses, onto a vertical plate. It was hypothesised that vertical reach (V. distance from floor to uneaten pellets) would be a function of distance between barrier and plate (20. 30. 40. 45. 50 cm). height of step (0. 14.2. 28.4. 42.6 cm) on which sheep placed their forelegs, and body size. With the exception of the largest sheep most were unable to reach pellets either when the barrier-to-plate distance was 45 and 50cm, or when the foreleg-step height was 42. 6 cm. Mean (s.e) V values decreased with step height (e.g. at 0 cm step. 103.83.04. 96.23.23 and 82.14.3 7cm. at 20. 30 and 40 cm plate distances respectively; at 20cm plate distance, 103.83.04.118.72.83 and 131.92.91 cm at 0. 14.2 and 28.4 cm step heights respectively). Linear regression of V on body weight and linear dimensions (e.g. withers height and rump height) showed high correlations (R²> 0. 8). V could be predicted from either M (R²>0. 7) or a combination of rump height and withers height (R²>0.9). The results confirm relationships found in a previous investigation with goats but demonstrate that sheep have a smaller reach than goats. The data will facilitate the design of mangers for sheep with body dimensions in the range of those used.

Keywords: horizontal reach, vertical reach, sheep, tombstone barrier, body dimensions

Tanzania J. Agrlc. Sc. (2000) Vol. 3, No. 2, 137 -146