LAUSR

Whole cottonseed (WCS) has long been a viable supplement in southern beef production systems, but new cultivars and ginning innovations have renewed interest in its use. Ad libitum supplementation of WCS, however, leads to increased fat intake, potentially resulting in reduced fiber digestibility. However, gestating and lactating beef cows have been observed to have adequate or optimum performance under supplementation scenarios as much as 3.6 kg∙animal-1∙day-1. It has been hypothesized that WCS may pass through the gastrointestinal tract without being digested, thereby not interfering with whole diet digestibility. Thus, our objective was to conduct an observational screening of beef cattle offered near ad libitum levels of WCS for passage dynamics. In this case study, we sampled beef cattle (approximately 1,000 head) at a farm in central Alabama offered an average of 3.6 kg WCS∙animal-1∙day-1. Cattle were divided by age and stage of production across seven pastures varying in forage base. Fresh manure samples (n = 22) were collected at random from the herd. Fecal samples were sorted by wet sieving to recover undigested seed material. Counts were conducted to determine whole or fractional seed remaining. Data were analyzed using SAS v. 9.4. Across samples, recovered WCS were approximately normally distributed (W = 0.83) with a mean of 3.3 seed per sample and a range of 2 to 76. Fractional WCS recovered were normally distributed (W = 0.92) with a mean of 31.9 parts per sample and a range of 0 to4. On average, WCS recovered accounted for 0.34 g per sample, or 5.0% of the DM recovered. While caution should be used in broad interpretation of these observational results, there is sufficient evidence to suggest that high levels of WCS supplementation may seed to decreased digestive efficiency (evidenced by undigested seed in manure). These observations serve as a basis for further investigation in designed experiments to evaluate WCS digestion and passage dynamics.