If you’ve heard me do a presentation at a meeting in the past few years, there is a good chance somewhere in the presentation I’ve talked about feeder design. As our sale weights increase, feeder dimensions need to increase also so the bigger pig can continue to have a ‘quality’ eating experience.
In reviewing some of the research on eating behavior in the past few weeks, the impact of sex (barrow versus gilt) came up. We know that barrows eat more than gilts, generally beginning around 70-80 lb. This difference in intake (with minimal differences in daily lean gain) is why barrow diets are most often formulated to have lower nutrient densities than gilt diets.
Dr Tami Brown-Brandl at the USDA Meat Animal Research Center in Clay Center, NE published an interesting paper a few years ago examining the eating behaviors of pigs in group housing situations. In pens of 35-40 pigs with a 5 hole feeder (7-8 pigs/hole) using RFID ear tags she was able to log the amount of time individual pigs spent at the feeder every day.
Beginning at approximately 9 weeks post-wean, barrows started to spend more minutes per day at the feeder than gilts in the same pen. This suggests that the rate of ingestion is similar for both sexes so the barrows have to spend more time at the feeder to consume higher amounts of feed daily.
Both sexes plateaued in time at the feeder around 90 days post-wean with barrows spending 14 minutes more per day at the feeder than gilts (85 vs 71 min/pig/d). The plateau for both suggests that the rate of ingestion was now increasing in a similar manner for both sexes since both had to eat faster if the time at the feeder didn’t change but total daily feed increased as the pigs grew.
These results raise a lot of questions. For instance, is the plateau that Dr Brown-Brandl observed a biological limit (i.e. the pig will only spend so much time at a feeder regardless of the amount of access provided) or a limit because of the pen dynamics and feeder used? Because barrows spent more time at the feeder than gilts, do we need to provide more feeder spaces in barrow pens?
Because they individually weighed all pigs, the research group was able to also identify behaviors of slow growing and fast growing pigs in pens. Not surprising, slow growing pigs spent less time at feeders than fast growing pigs. However, once the fast growing pigs were sold, the time at the feeder for the slow growing pigs increased dramatically (going above 100 min/pig/d). This suggests that pig behavior as it impacts access to feed is a contributor to slow growing pigs. Does this same interaction of behavior on time at the feeder hold if we have pens of 125 pigs where we know the social dynamics of the pen change? Are there feeder designs that allow the slow grower to feel safer at the feeder (less chance of being forced out by the aggressive pig)?