Proceedings of the New Zealand Society of Animal Production.
1966, 26: 71-85
Proceedings of the New Zealand Society of Animal Production.
1966, 26: 71-85
The effect of restricting the time available to cows for grazing each day to either four hours or eight hours has been compared with unrestricted grazing, and the contribution of supplementary feeding with hay of good to average quality has been assessed under these conditions.
Experimental treatments were applied for three weeks, of which the first week comprised a changeover period, and experimental results were assessed from productions for the last two weeks.
A split-plot Latin square design was used, individual members of each of twelve sets of identical twins being allocated either or one group which was fed hay as supplement or to a second group fed on grass alone. These groups were designated "hay" and "no hay". Grazing times were allocated to cows of the same set according to the arrangement of a 3 x 3 latin square, of which there were four replicates.
It was shown that both grazing time and the feeding of hay as a supplement had large and statistically significant effects on milk yield, milk composition and liveweight. Under the conditions of the trial, the feeding of hay after four hours grazing produced a greater increase in milk yield and milk solids than doubling the time available for grazing.
Cows restricted to eight hours' grazing, on average, consumed 9 1b hay daily and produced similar amounts of milk and milk solids as when given unrestricted grazing. It has been estimated that under these conditions the efficiency of conversion of the total feed consumed to milk was appreciably higher when the diet was grass alone, since approximately 2 lb of hay was required for each additional pound of fat-corrected milk.
The short-term economics of the conversion of hay to milk have been examined, and it has been concluded that under conditions similar to those applying in the present trial, a comprehensive appraisal of likely responses to a complete range of different supplements, including concentrates, is required.
Attention has been drawn to the appreciable amount of hay consumed where grazing was unrestricted, although this did not increase production significantly.
The merits and disadvantages of the current experiment have been discussed, and requirements for further study of this problem of adequately feeding cattle in early lactation have been outlined. Within this context, the importance of initiating and developing complementary investigations into the effect of differing management systems on pasture growth, utilization and yield, and on soil structure and fertility is stressed. These must proceed within the local problem environment.
Keywords: NZSAPAB;
