Milk yield is determined by a wide range of factors, including genetics, housing, management and health status of individual cows and the herd. Of course, nutrition plays a large part, as well. There are several stages to feeding cows – planning the ration with your nutritionist, making up the ration on-farm, feeding it to the cows and ensuring that intakes are maximised, and finally, enabling cows to fully digest the ration, so that they get the most out of the feed supplied.
This last point is where Glycal Forte® makes its mark. As a nutricine, the main effect of Glycal Forte® is to enable the rumen to more fully digest and utilise what the cow eats. This is done in two ways, firstly, by its effect on rumen pH and secondly, by its effect on rumen microbial biomass.
Glycal Forte® acts to stabilise the rumen pH at optimal level, above pH 6.0. Cows are at risk of low rumen pH or subacute ruminal acidosis (SARA) if there is too much starch and sugar or too little physically effective fibre in the ration, or if they sort the ration too much. In addition, cows are inevitably at risk of SARA for about one month after calving. Dairy cows undergo a period of rumen adaptation after moving from a less energy-dense dry cow ration to a more energy-dense milking ration. It can take up to 6 weeks for the rumen to adapt and reach maximum ability to absorb volatile fatty acids, which are the products of rumen fermentation. So, for about a month after calving, as these acid levels build up in the rumen, cows are inevitably at high risk of SARA (Humer et al., 2018). There are four effects of low rumen pH on the cow’s energy balance:
The effect of Glycal Forte® on rumen pH post-calving was demonstrated in a trial carried out on 90 cows in a high-yielding (>10,000 litres) UK dairy herd:
Glycal Forte’s® ability to optimise rumen pH means that not only do cows eat more, but they utilise the feed better because of the effects on the rumen bacteria. This leads to more energy being made available to the cow for milk production and other needs.
Glycal Forte® also has a beneficial effect on rumen biomass; more rumen biomass means more microbial protein. When compared to glycerol drench, feeding Glycal Forte® results in less gas (carbon dioxide and methane) production and therefore less energy wasted. Laboratory trials show that adding Glycal Forte® to feed increases rumen biomass and hence supplies more microbial protein. The effect below was seen at a constant pH of 6.85.
Rumen bacteria are the main source of protein used by cows, and most protein in the mature cow is used by the udder for milk protein.
Therefore, the nutricine action of Glycal Forte® enables the diet to deliver more energy and protein to the cow, which can be used to support increased yields. An increase of 2-3 litres, in addition to other benefits, has been seen when Glycal Forte® is fed on commercial farms.