Eating behaviour

Eating behaviour

Several studies have provided data on differences in the eating behaviour of different breeds that may be associated with DM intake capacity and production efficiency. Prendiville et al. (2009) investigated differences in grazing behaviour among Holstein, Jersey and Jersey X Holstein cows under an intensive seasonal grass-based environment. They reported little differences among breeds for grazing time, number of grazing bouts, grazing bout duration and total number of bites. In absolute terms, Holstein cows had higher grass DM intake per bite and rate of intake per minute but Jersey cows had more grazing mastications. However when the grazing behaviour parameters were expressed both as per 100kg of BW or per kg DM intake, Jerseys had longer grazing times, and higher total bites, bite rate, and amount DM per bite [Prendiville et al., 2010].

It is clear from the results obtained by Prendiville et al. (2010) that inherent grazing and ruminating differences do exist between cows varying in intake capacity and production efficiency. Furthermore, their results imply that Jersey cows with higher intake capacities have increased grazing time and rate of DM intake per unit of BW. Increased production efficiency, on the other hand, would appear to be aided in particular by improvements in mastication behaviour during grazing. Similarly, Vance et al. (2012) found that, when expressed on a metabolic BW basis, Jersey X Holstein crossbred cows had a higher DM intake than Holsteins, with this being facilitated by a longer time spent grazing and a greater number of grazing bites per day. They suggested that the smaller cross-bred cows had a greater ‘grazing drive’ that enabled them to compete with larger, Holstein herd-mates, and may be more capable of maintaining normal grazing behaviour in adverse weather conditions.

Aikman et al. (2008) compared the eating and rumination behaviour, rate of passage and diet digestibility of Jersey and Holstein cows fed a total mixed ration (TMR). They found that Jerseys spent more time eating and ruminating per unit of ingested feed than Holsteins and distributed their meals more evenly throughout each 24-hour period, providing a more regular supply of feed to the rumen. This was despite finding that the two breeds did not differ in DM intake per unit of BW.

When eating a mixed ration, dairy cows sort feed particles, usually in favour of smaller particles (grain, protein meals) and against longer forage components (i.e. straw, hay, silage) [Miller-Cushon and DeVries, 2017]. Perceived palatability of individual ration ingredients is likely to be a main driver of feed sorting, and sorting in favour of smaller particles is consistent with a preference for sweet flavours [Nombekela et al., 1994]. However, cows have been shown to alter their feed preferences in favour of more physically effective forage particles when induced with sub-acute ruminal acidosis (SARA) [Maulfair et al., 2013; Kmicikewzcz and Heinrichs, 2015]. The extent to which cows do this impacts on their intakes of intake of highly-fermentable carbohydrates and effective fibre, and therefore on rumen pH, milk composition and the risk of ruminal acidosis While differences between Jerseys and other breeds in feed sorting behaviour and preference for different ingredients when offered mixed rations have been observed in practice, they have not been investigated in controlled research studies. Knowledge on differences between Jerseys and other breeds in their eating rate, sorting behaviour and ingredient preferences would be useful to guide the feeding management of Jersey herds and Jersey cows within mixed-breed herds housed in confinement systems (freestall barns, compost bedded pack barns, dry-lots) in which TMRs are fed.

A series of short-term experiments could be conducted using an approach similar to that used by Sporndly et al. (2006). A measured quantity of a mixed ration with measured proportions of long fibrous ingredients (hay, silage), grains, protein meals, wet and dry by-products would be prepared. The ration would be passed through a set of sieves (Penn. State shaker box) prior to offering this ration to cows. After the meal commenced, it would be briefly interrupted at pre-set