Potential undesirable impacts of nutritional management on the behaviour of dairy cows can be intensified under situations where cows do not have good access to their feed (i.e. as result of higher stocking densities at the feed bunk). When feed bunk competition is high (for example when feed bunk space is limited), increases in aggressive behaviour limit the ability of some cows to access feed at times when feeding motivation is high, particularly after the delivery of fresh feed (DeVries et al., 2004; Huzzey et al., 2006). As result, increased feed bunk competition will increase feeding rate at which cows feed throughout the day, resulting in cows having fewer meals per day, which tend to be larger and longer (Hosseinkhani et al., 2008). Feed bunk competition may also force some cows to shift their intake patterns, such that they will consume more feed later in the day during the later hours after feed delivery after much of the feed sorting had already occurred. These effects of feed bunk competition on feeding behavior patterns, and the potential to reduce DMI, may be greatest for transition dairy cows (Proudfoot et al., 2009).
Reducing feed bunk competition, by providing adequate feed bunk space (to allow animals to eat simultaneously), particularly when combined with a physical partition (e.g. headlocks or feed stalls), will improve access to feed, particularly for subordinate dairy cattle (Endres et al., 2005; DeVries and von Keyserlingk, 2006; Huzzey et al., 2006). This, in turn, will contribute to more consistent DMI patterns, both within and between animals, as well promote healthy feeding behaviour patterns. It is, thus, not surprising that Sova et al. (2013), found in a cross-sectional study of parlour-milked, free-stall herds that every 10 cm/cow increase in feed bunk space was associated with 0.06 percentage point increase in group average milk fat and a 13% decrease in group-average somatic cell count. With greater bunk space, cows are able to consume their feed in a manner much more conducive to stable rumen fermentation, and thus greater milk fat production. Further, with more bunk space cows would not be forced to choose to lie down too quickly after milking rather than compete for a feeding spot, and thus reduce their risk of intramammary infection. The impact of greater feed bunk space is not limited to conventionally milked cows. Deming et al. (2013) recently found in a cross-sectional study of robotic milked herds that every 10 cm/cow increase in feed bunk space was associated with a 1.7 kg/d increase in daily milk production per cow.