Beneficial effects of a calf starter versus forage on rumen development and bacteria populations in beef calves

Rumen development depends on the intake of solid food that is fermented into volatile fatty acids that stimulate the development of the rumen papillae in calves. The starter feeding can promote the growth of papillae in the rumen and as a consequence an earlier weaning. We evaluated the effects of calf starter on ruminal development, and productive response of lactating bull calves raised for meat in the tropics. Twelve male Brahman x Swiss American cross beef calves from a dual-purpose system were randomly assigned two treatments with six animals per treatment: milk-fed calves + Taiwan grass (Pennisetum purpureum, MT) and MT + calf starter, (MTS). Feed intake and growth were measured at 7-day intervals throughout until 210 d of age. At 90 days old, three calves from each treatment were harvested, and fluid and ruminal tissues were collected from the cranial, ventral, dorsal, and dorsal blind ruminal sacs for measurements of many papillaes per cm(2) (NP), papillae length (LP) and papillae width (WP). Ruminal bacterial genotype identification was determined by amplicon generation with the Illumina platform. Calf starter-improved weight (Live weight, LW) and average weight gain (ADG) and NP, but, LP and WP was similar in both treatments (p < 0.05). In calves with starter feed treatment, we observed the bacteria Desulfonauticus autotrophicus sp. nov. that was not previously reported in ruminants. Use of calf starter showed benefit for calves with improved feed intake and rumen development because promoted a greater number of rumen papillae.