Theme 08: Grazing Ecology
Description
This study was undertaken during winter, spring and summer 1997, located in the basaltic region of Uruguay to evaluate the effects of stocking rate (SR) and N and P fertilizer application on sward characteristics and on sheep and cattle diet selection and grazing behaviour. The treatments applied were: a) control (C; without fertilizer application using a SR of 0.9 stock units (SU)/ha), b) T1 (with N and P fertilizer application using a SR of 0.9 SU/ha), c) T2 (with N and P fertilizer application using a SR of 1.2 SU/ha) and d) T3 (with N and P fertilizer application using a SR of 1.5 SU/ha). In general, compared with C, fertilized treatments resulted in increments in sward surface height (SSH) and sheep bite weight (BW): a) winter (3, 8, 5 and 5 cm., P < 0.01; 79, 142, 139 and 92 mg DM/bite, P < 0.05), b) spring (3, 8, 5 and 6 cm., P < 0.01; 108, 188, 115 and 215 mg DM/bite, P < 0.01), and c) summer (7, 14, 11 and 8 cm., P < 0.01;146, 199, 182 and 131 mg DM/bite, P < 0.05) for C, T1, T2 and T3, respectively. In general, the nutritive value of diet selected by sheep and cattle was higher than that of the pasture on offer, and higher in sheep than in cattle: a) winter (17, 18 and 16% crude protein, CP, P < 0.05; 39, 37 and 41% acid detergent fiber, ADF, P < 0.05), b) spring (11, 14 and 11% CP, P < 0.05; 42, 33 and 37% ADF, P < 0.01), and c) summer (8, 10 and 9% CP, P < 0.05; 50, 40 and 45% ADF, P < 0.01) for pasture on offer, sheep and cattle diets, respectively. This study demonstrated the importance of fertilizing native swards to improve production, structure, nutritive value, and animal carrying capacity and animal performance. It also shows the important role that diet selection plays in determining the nutritive value of the forage eaten by sheep and cattle, and stresses the greater selective ability of sheep over cattle.
Included in
A Sheep and Catlle Diet Selection Study on a Fertilized Native Sward in Uruguay
This study was undertaken during winter, spring and summer 1997, located in the basaltic region of Uruguay to evaluate the effects of stocking rate (SR) and N and P fertilizer application on sward characteristics and on sheep and cattle diet selection and grazing behaviour. The treatments applied were: a) control (C; without fertilizer application using a SR of 0.9 stock units (SU)/ha), b) T1 (with N and P fertilizer application using a SR of 0.9 SU/ha), c) T2 (with N and P fertilizer application using a SR of 1.2 SU/ha) and d) T3 (with N and P fertilizer application using a SR of 1.5 SU/ha). In general, compared with C, fertilized treatments resulted in increments in sward surface height (SSH) and sheep bite weight (BW): a) winter (3, 8, 5 and 5 cm., P < 0.01; 79, 142, 139 and 92 mg DM/bite, P < 0.05), b) spring (3, 8, 5 and 6 cm., P < 0.01; 108, 188, 115 and 215 mg DM/bite, P < 0.01), and c) summer (7, 14, 11 and 8 cm., P < 0.01;146, 199, 182 and 131 mg DM/bite, P < 0.05) for C, T1, T2 and T3, respectively. In general, the nutritive value of diet selected by sheep and cattle was higher than that of the pasture on offer, and higher in sheep than in cattle: a) winter (17, 18 and 16% crude protein, CP, P < 0.05; 39, 37 and 41% acid detergent fiber, ADF, P < 0.05), b) spring (11, 14 and 11% CP, P < 0.05; 42, 33 and 37% ADF, P < 0.01), and c) summer (8, 10 and 9% CP, P < 0.05; 50, 40 and 45% ADF, P < 0.01) for pasture on offer, sheep and cattle diets, respectively. This study demonstrated the importance of fertilizing native swards to improve production, structure, nutritive value, and animal carrying capacity and animal performance. It also shows the important role that diet selection plays in determining the nutritive value of the forage eaten by sheep and cattle, and stresses the greater selective ability of sheep over cattle.
