It has been demonstrated that better grown calves and heifers have higher first lactation and lifetime production than less well grown ones. What is less certain is the extent to which the benefits of early rumen development remain through to and after calving, with heifers reared off farm.
This was tested in an on farm trial by Agrifeeds/Agritrade, where Friesian and Friesian Cross calves were reared either on a conventional whole milk and meal or restricted whole milk and an extruded calf pre-starter system, designed to promote early rumen development. Both sets of calves were weaned when eating about 1.5 kg meal at around 8-9 weeks old.
The calves were combined in one group, and remained on the farm until 5 months old, then grazed on a run off until about 6 weeks prior to calving aged 2 years. Herd tests recording milk production were performed on five occasions over 9 months of their first lactations. Milk solids yields averaged 0.21-0.35 kg/cow higher with the early rumen development than the conventionally reared group at each of the herd tests.
The higher milk and milk solids yields of the early rumen development group were statistically significantly higher in four out of the five herd tests, which is remarkable for an on farm trial, and that both groups had been fed and managed together since weaning. These results confirm the benefits of similar trials on other farms, comparing early rumen development using an extruded pre-starter with conventionally reared calves. Similar improvements in milk solids yields were recorded on these farms.
Comparisons between early rumen development and conventional rearing have been conducted on cows during later lactations, with the former group appearing to outperform the latter group during their 2nd and 3rd lactations. Calculations based on performance data also indicate the early rumen development cows have improved life time performance.
These trials help demonstrate the importance of early rumen development in setting cows up for improved milk production starting with their first lactation, and continuing throughout their productive lives, which is important when trying to improve profitability irrespective of the milk payout.
As featured in NZ Dairy Farmer