Digestive development in neonatal dairy calves with either whole or ground oats in the calf starter

Abstract

A series of 3 trials was conducted to determine effects of whole or ground oats in starter grain on reticulorumen fermentation and digestive system development of preweaned calves. Male Holstein calves (43.1±2.3kg at birth; n=8, 9, and 7 for trials 1, 2, and 3, respectively) were housed in individual pens in a heated facility; bedding was covered with landscape fabric to prevent consumption of bedding by the calves. In trials 1 and 2 only, calves were fitted with rumen cannulas by wk 2 of life. In all trials, a fixed amount of starter (containing 25% oats either ground and in the pellet or whole) was offered daily; orts were fed through the cannula in trials 1 and 2. Calves were randomly assigned to an all-pelleted starter or pellets plus whole oats. Rumen contents (trials 1 and 2) were sampled weekly at -8, -4, 0, 2, 4, 8, and 12 h after grain feeding for determination of pH and volatile fatty acids. Calves were killed 3 wk (trial 1) or 4 wk (trials 2 and 3) after grain was offered; organs were harvested, emptied, rinsed, and weighed to gauge digestive organ development. Starter intake was not different between treatments. Weekly measurements of rumen digesta pH did not change and only subtle changes were observed in molar proportions of individual volatile fatty acids. Molar proportion of butyrate and pH linearly decreased with age, whereas acetate proportion increased. Reticulorumen weight and papillae length tended to be greater for calves fed pelleted starter, whereas abomasum weight was greater for calves fed pellets plus whole oats. Fecal particle size and starch content were greater for calves fed pellets plus whole oats. Under the conditions of this study, physical form of oats in starter grain did not affect rumen fermentation measurements; greater rumen weight and papillae length in calves fed pelleted starter may be the result of greater nutrient availability of ground oats. Under the conditions of this study with young calves on treatments for <4 wk, increasing particle size of the starter by feeding whole oats did not affect rumen fermentation nor did it improve digestive system development.

Straw particle size in calf starters: Effects on digestive system development and rumen fermentation

“…Total concentration of VFA in the rumen increased with age as has been reported by earlier studies (Greenwood et al, 1997;Beharka et al, 1998;Coverdale et al, 2004). In our previous study (Suarez-Mena et al, 2015), rumen VFA concentration increased with age in a quadratic trend with a small decrease at wk 4, which is somewhat similar to the current study where a plateau was observed between wk 3 and 5 and then an increase at wk 6. The decrease observed in Suarez-Mena et al (2015) and plateau in the current study are likely an effect of greater VFA absorption, because intake increased with time and it is assumed VFA production increases with greater intake.…”

“…Figure 2 illustrates pH variation over time after feeding grain; a nadir was reached at approximately 2 h postfeeding for wk 2 and 6, and at 4 h for wk 1, 3, 4, and 5. The postprandial pH variation is comparable to what we observed in a previous study with similar management (Suarez-Mena et al, 2015). Anderson et al (1987) observed lowest pH values 1 to 3 h postfeeding and a faster recovery to prefeeding values than in the present study; at its nadir average pH was over 5, which was higher than what we observed in the present study.…”

“…Greenwood et al (1997) also observed higher rumen pH with diets greater in particle size when forage constituted 15% of starter. The decline in pH with age is consistent with Suarez-Mena et al (2015), where calves were fed grain for 4 wk. When calves were studied for a longer period of time, Anderson et al (1987) and Beharka et al (1998) reported a quadratic response of pH to age, but it declined consistently for about 6 wk.…”

“…In both studies, calves fed smaller particle size rations had increased keratinization of the rumen papillae, which has been shown to reduce the amount of VFA absorption (Hinders and Owen, 1965). In our previous study (Suarez-Mena et al, 2015) and in the Greenwood et al (1997) study, particle size of diets did not affect VFA concentration. Total concentration of VFA in the rumen increased with age as has been reported by earlier studies (Greenwood et al, 1997;Beharka et al, 1998;Coverdale et al, 2004).…”

The importance of calf sensory and physical preferences for starter concentrates during pre- and postweaning periods

“…However, differences in rumen pH between calves consuming whole or steamed-rolled concentrates may not have been sufficient to provoke changes in straw intake, in part because rumen pH values were >6.0 in both treatments in the present study, in contrast to Lesmeister and Heinrichs (2004), who reported values between 5.4 and 5.8. Suarez-Mena et al (2015) observed only minimal changes in the rumen fermentation profile when offering whole or ground oats from wk 1 to 4 of age, and attributed the lack of difference to the young age of calves. Similarly, in the present study the major changes in rumen fermentation profile were observed at 50 d but not at 35 d. Similar to Beharka et al (1998), in the present study, the butyrate molar proportion increased and branched-chain VFA decreased with time.…”