CASE STUDY: Effect of high- and low-cereal-grain starters on straw intake and rumen development of neonatal Holstein calves

A high-cereal-grain, coarse, textured calf starter (TEX) was compared with a fine-particle, pelleted, low-cereal-grain starter (PEL) for the effect on straw intake and rumen papillae development. Two-day-old calves were fed a 27% CP, 17% fat milk replacer at 0.66 kg of DM daily and weaned at d 35. Calves were fed TEX or PEL (20% CP) and straw ad libitum with water over a 56-d trial. Calves were housed in individual pens with geotextile fabric over rock as flooring with no bedding. After slaughter on d 56, gastrointestinal tracts were divided into stomach and intestine at the pyloric sphincter and weighed. Rumen wall and rumen papilla samples were measured, and kidneys with associated fat were measured. Data were analyzed as a completely randomized design. Straw intake averaged 0.8% of total intake and did not differ by starter type. Calves fed TEX had greater final BW and greater ADG than did calves fed PEL. Empty stomach weight was greater for calves fed TEX. Intestine plus digesta weights were less and stomach and intestine plus digesta weights were less for calves fed TEX compared with those fed PEL. Rumen papilla length was greater for calves fed TEX compared with those fed PEL. Percent kidney fat was greater for calves fed TEX compared with those fed PEL, and it increased linearly with ADG. Simulated straw intake was very small. Feeding a coarse, textured, high-cereal-grain diet increased rumen papilla length and contributed to less stomach, intestine, and digesta as a percentage of BW than did feeding a fine-particle, pelleted, low-cereal-grain diet.