Focus on feeding

Researchers at the University of Guelph have recently assessed the impact of feeding management on herd performance (Sova et al., 2013. J. Dairy Sci. on-line. 96:1-12). We know from European research (Bach et al., 2008. J. Dairy Sci. 91:3259) that ensuring 24-hour feed availability results in much greater milk production. Herds feeding the same TMR that allowed for feed refusals and pushed up feed more often out-produced other herds with similar genetics by 3.5 to 8.6 lb/cow daily!

The Guelph study focused on TMR feeding frequency, amount of feed refusal, and bunk space. They evaluated 22 free-stall herds with an average herd size of 162 cows. Information was collected on a group basis with an average group size of 83 cows. Some herds had only one group of cows, but if the herd had more than one group then the highest milk group was observed. Groups averaged 187 days in milk with a mean parity of 2.3 lactations; cows consumed 53.6 lb/d dry matter intake and produced 75.6 lb/d of milk.

What is fascinating about this work is that the researchers were able to measure the relationships between feeding management and group performance. For instance, twice per day feeding compared with only once per day was associated with an average increase of 3.1 lb/d of DMI, 4.4 lb/d more milk, and a 0.86 percentage-unit decrease in sorting against the long particles in the diet (measured as being greater than 19 mm with the Penn State Particle Separator).

Feeding for lower refusal rates also was associated with less feed sorting on a pen basis. Sorting had a substantial impact on these cows: Every 2% greater sorting against long particles was associated with a 2.2 lb/d loss in milk yield. We know that drier diets and feeding for higher amounts of feed refusal typically results in more sorting. In contrast, a diet with more homogeneous particle size results in less sorting, but a diet with distinct larger and smaller particle fractions allows cows to more easily select the desired particles (usually the smaller particles that are higher in starch). Interestingly, greater milk yield was associated with less sorting for fine particles. Additionally, efficiency of milk production decreased by 3% for each 1% increase in sorting for fine particles which may reflect an elevated risk for low rumen pH and consequently lower feed efficiency.

Increasing feeding frequency of TMR from one to two times daily promoted greater feeding time and a more consistent distribution of meals throughout the day. We all know the rumen benefits of more equally spaced meals: lower risk of subacute acidosis, lower diurnal fluctuations in pH, and potentially better fiber digestion and dry matter intake. Even though there is a benefit of feeding TMR twice versus once daily, the benefits of even greater feeding frequency are still debatable. Last year I reviewed the literature and found that milk yield actually decreases when TMR feeding frequency is 3 times/day or greater and is linked with a reduction in resting time.

A 4 in/cow increase in bunk space was associated with a 0.06 percentage-point increase in milk fat and a 13% reduction in somatic cell count. We would expect that the improvement in milk fat relates to improved feeding behavior and rumen fermentation. Here’s a thought-provoking finding: Use of headlocks was related with a 43% decrease in SCC versus post and rail feed barriers. We know that headlocks provide more protection from competitive displacement at the bunk, especially with overcrowding. Could it be that cows lie down more quickly in competitive environments and increase their risk of mammary infections? This finding needs more work to determine if it is repeatable and is something for farmers to be concerned about.

Here’s one more useful finding: we understand that water is the most important (and too often neglected) nutrient – and this study highlighted its importance. For each 0.8 in/cow increase in water-trough space, milk increased by 1.7 lb/d.

The bottom line: feeding practices that ensure feed accessibility throughout the entire day promote greater feed intake, milk yield, and efficiency of production. These on-farm data accentuate the importance of never losing sight of the fundamentals of feeding management.

Sova et al., 2013. J. Dairy Sci. on-line. 96:1-12

Bach et al., 2008. J. Dairy Sci. 91:3259

By Rick Grant, The Miner Institute