Do Pen Design, Feedbunk Space and Stocking Density Affect Digestive Health?

Background

Most research aimed at optimizing rumen health has looked at things like forage inclusion rate, grain processing, bunk and feeding management and antimicrobials. However, pen design, bunk space and stocking density could affect animal health and welfare, particularly on high grain finishing diets. When there isn’t enough bunk space for all animals to eat at the same time, animals that are lower in the pecking order will have less time to eat (and will potentially consume more fine feed particles). This could increase the risk of acidosis and abscesses in those less dominant animals.

Industry recommendationsregarding feedlot pen design, bunk space per head and pen stocking density were developed many years ago. Fewer feeder cattle are horned now, but enter and leave the feedlot at much larger sizes. Roller compacted concrete is becoming a popular choice among some cattle feeders. This improves drainage, pen conditions and animal cleanliness, but also allows higher animal densities. Animals will interact more frequently in more densely stocked pens. This could affect feeding behavior, as well as overall stress levels, which may impact animal performance and health.

Objectives

• Assess the consequences of increased competition for space on animal temperament and stress
• Determine the role of feed bunk space and pen stocking density on the development of rumen acidosis and liver abscesses
• Analyze the costs associated with the different space allowances tested

What they Did

Portable fencing was used to modify the shape of pens in a research feedlot. The researchers compared three stocking rates (industry standard 15m² vs. 30 or 7.5 m² per head or 161 vs. 323 or 81 square feet), each with two different feed bunk allowances (0.3 vs. 0.6 m per head, or 1 vs. 2 feet). A total of 900 head of steers were fed for 116 days in each of three years (50 head per pen). Cattle were fed once daily, using slick bunk management.

Animals were weighed every 28 days, and intake was measured on a pen basis. Three animals per pen were fitted with rumen pH monitors. Animal standing, lying, feeding, drinking, and interactive behavior was monitored by video. Animal temperament was evaluated using chute behavior score and exit speed on weigh days. Hair cortisol was measured as an indicator of stress. Carcass grade and liver abscesses were evaluated at slaughter.

The economic evaluation compared the differences in construction costs to statistically significant differences in carcass parameters among the treatments.

What They Learned

The results from this study showed that neither increasing the feed bunk allowance (from the standard 0.3 m per head to 0.6 m per head), nor halving or doubling pen space allowance resulted in major changes to the growth performance, temperament, chronic stress, rumen pH or carcass traits of finishing steers.

The only substantial effect of increasing the space allowance in the feed bunk was the 18% increase in the proportion of carcasses graded as AAA, although this also came with an unexpected increase in the proportion of livers with either minor or severe liver abscesses.

Pen size did affect the behaviour of steers in the pen, with the 15 m² group showing a greater proportion of steers at the feed bunk and at the water bowl, and a lower proportion of steers laying down compared to the other treatments. These changes may have to do with the physical amount of space available to the animals, and did not seem to impact any other parameter measured.

The lack of statistically significant findings for ADG and DMI suggests feedlots would be unwilling to reduce the number of head per pen to achieve wider bunk space allotments or lower pen densities in their existing pens as doing so would reduce their total feeding capacities by 47-50%. Reducing the number of head fed in pens without statistically significant positive impacts on ADG and DMI is not economically feasible.

What it Means

Cattle are fairly flexible in their ability to adapt and cope with varying space allowances, both at the pen and at the feed bunk. This versatility allowed steers to perform similarly in the conditions imposed by this study. Results should be taken cautiously, however, as we did find that the smaller pens had difficulties draining moisture due to manure accumulation, particularly in periods of rainfall, which caused a visually noticeable difference in the accumulation of mud in the floor and on the coat of the steers. Hence, the results from this study could vary from feedlot to feedlot depending on the design and slope of the pens, the humidity, precipitation and weather patterns.