In preruminant calves, milk is bypassing the rumen by closure of the oesophageal groove and flows directly into the abomasum. Leakage from the oesophageal groove or backflow of milk from the abomasum into the rumen, however, leads to fermentation of the milk replacer and results in reduced performance, meat quality and increased mortality. Several studies have elucidated the mechanism and aetiology of groove closure. In this study (originally not designed to study ruminal drinking) the diurnal pattern of the respiratory quotient (RQ) and methane production in a bloating calf was compared with that of normal calves. Individually housed calves were studied during two, 9-day periods using indirect calorimetry. Milk replacer was fed at 1.5 x MEm and no roughage was supplied. A clinical case of ruminal drinking spontaneously developed in one of the six calves. The calf was bloating and faeces were clay-like. Nutrient digestibility and gas exchange measurements were compared between this calf and five normal calves. Apparent digestibility of crude protein (86 percent vs 91 percent) and crude fat (82 percent vs 92 percent) was depressed in the bloating calf compared with the other calves. Marked differences in RQ and methane production were observed at 1.5 h postprandially. RQ increased from 0.78 to 1.13 in the bloating calf and from 0.80 to 0.88 in the normal calves. This can be ascribed to anaerobic fermentation of the milk replacer in the rumen, which theoretically results in an infinite RQ and a concomitant production of methane. Methane production, at the same time, increased from 73 mL/kg0.75/d before feeding to 428 mL/kg0.75/d at 1.5 h after feeding in the bloating calf, and from 25 mL/kg0.75/d to 65 mL/kg0.75/d in normal calves. Based on these observations, it is hypothesised that measurement of O2, CO2 and CH4 in breath 1-2 h post-feeding may provide a sensitive indicator for identification of ruminal drinking. The sensitivity of this methodology, however, needs further study.
|Pages (from-to)||365 (W209)|
|Journal||Journal of Animal Science|
|Publication status||Published - 2004|