Animal feed resources information system

Chaves et al., 2006. Asian-Aust. J. Anim. Sci., 19 (9): 1271-1282

Document reference 
Chaves, A. V. ; Woodward, S. L. ; Waghorn, G. C. ; Brookes, I. M. ; Burke, J. L., 2006. Effects on performance of sulla and/or maize silages supplements for grazing dairy cows. Asian-Aust. J. Anim. Sci., 19 (9): 1271-1282

The objective of this study was to investigate the effects of either maize or sulla silage supplementation on grazing dairy cows during summer. Forage mixtures used in the 4 week trial were based on previous experimental results but inclusion of rumen fistulated cows in 5 treatments enabled rumen sampling and use of in sacco incubations to determine the diet effects on digestion kinetics. Sulla and maize silages were used to supplement pasture and to meet the minimum requirements for dietary protein concentration. Five groups of 10 cows were grazed on a restricted daily allowance of 18 kg dry matter (DM) pasture/cow to simulate a summer pasture deficit, and 4 groups received an additional 6 kg DM/cow/day of silage (sulla, maize, or sulla and maize silages). Group 6 was given a relatively unrestricted (38 kg DM/cow/day) pasture allowance. The silage mixtures and pasture were incubated in sacco during the final week of the trial. The pasture had high nutritive value and not like the typical summer pastures. There was no difference in cow performance with the 4 silage supplemented groups and the low milk solids (MS) production (~1.0 kg MS/day) relative to full pasture (1.3 kg MS/day) showed the principal limitation to performance was dry matter intake. Milk composition was not affected by silage type and the low level of pasture substitution (0.29) suggested that metabolizable energy (ME) was the principal limitation to performance. Samples of rumen liquor and in sacco data demonstrated significant effects of supplement; DM degradation rates (k) was highest (0.084/h) when cows were fed 6 kg sulla silage, whereas diets with a high proportion of maize silage were slowly degraded (p<0.01). It is concluded that silage supplements can be used to fill summer feed deficits when pasture quality declines due to ryegrass maturity. To achieve positive response from supplements, supplements should be of higher nutritive value than pasture and must complement the pasture offered.

Citation key 
Chaves et al., 2006