In a herd consisting predominantly of animals with a long lactation period, it will be difficult to retrieve the milk lost during summer. The cows that calve in periods of greatest heat stress will tend to suffer an increase in the metabolic disorders typical of the post-partum period and will reach lower values of peak production. Moreover, by ingesting less dry matter, they will be more subject to a greater loss in weight, with negative impact on fertility. Negative effects will also be seen on cows in the dry period which, having spent the final part of pregnancy under the effects of heat stress, will show negative repercussions on mammary cell growth, with a consequent reduction in milk production during the imminent lactation and a delay in foetal growth with obvious limitations on genetic and productive potential (S. Thao and G. E. Dahl 2013).
Graph 3: The use of Biosprint® live yeast enables the group of primiparous cows to maintain optimum feed intake levels, with improved milk quality parameters.
It is therefore necessary to use both livestock management and nutritional preventive techniques in order to limit the negative effects of heat stress and to keep the herd’s performance at high levels of efficiency.
To show that nutritional strategies can help support the performance of cows during the summer months, last summer we tested feed intake and milk quality in a herd located in the province of Novara with 250 lactating cows. During the months of July and August, when temperature and humidity brought the THI to an average value of 76 and a peak value of 81, it was found that the constant use of Biosprint® (5 g/cow/day) improved the cattle’s performance.
The group of primiparous cows who received Biosprint® MUCL™ 39885 for the entire summer period maintained an optimal feed intake and showed an improved fibre digestibility, as a result of the yeast’s beneficial effect on the cellulolytic flora, which in turn improved the milk’s fat content (Graph 3).
The group of pluriparous cows, which did not receive yeast for the entire month of July, suffered a notable drop in feed intake as temperatures increased. Only by adding rations of Biosprint® to the feed was it possible to improve feed intake (Graph 4), production (+3.4 kg/cow/day) and milk fat content (Graph 5) for the pluriparous group as well.