Milk Clotting Activity in Bovine Fetal Abomasa

Abstract

Abomasa (vells) were removed from 30 fetal calves at each of the 6th, 7th, 8th, and 9th mo of development. Milk clotting enzymes were exhaustively extracted in 10% NaCl solutions from the dried abomasal tissue. Total enzyme activity at each stage of fetal development was compared with that from abomasa of 3 to 5-day-old milk-fed calves. Enzyme activity was present in the abomasa of bovine fetuses as early as the 6th mo of development and increased as the fetuses approached full term. Average activity recovered from fetal vells at the 6th, 7th, 8th, and 9th mo of development represented 2, 7, 12, and 31% of the activity per vell, and 8, 14, 22, and 38% of the activity per unit vell weight, of that recovered from high quality calf vells. Diffusion patterns on casein-agar gels produced by bovine fetal extracts differed from those produced by commercial calf rennet extract or porcine pepsin.

Effect of enhancing curd formation during the first colostrum feed on absorption of γ glutamy1 transferase by newborn calves

“…It takes 3 or more days of milk feeding before the abomasum adapts to a milk diet and develops substantial rennet activity. 14 Thirdly, amniotic fluid is usually present in the newborn's stomach and it possesses a proteinase inhibitor, which might inhibit rennin action. 15,16 The foetus swallows large amounts of amniotic fluid before parturition, and residual amniotic fluid in the gut at birth could inhibit curd development.…”

Short communication: Neonatal calves coagulate first-milking colostrum and produce a large curd for efficient absorption of immunoglobulins after first ingestion

“…Although abomasa of neonatal calves may contain amniotic fluid with slightly alkaline pH (Javed and Wright, 1990) that decreases hydrolytic activities of chymosin whose optimum pH for curd formation is 5.3 to 6.3 (Foltmann, 1970), our in vitro study found that at least 50% amniotic fluid in the colostrum did not influence coagulation. On the other hand, it is reported that milk coagulation activity is expressed in the abomasum of fetal calves from 6 mo of gestation and markedly increased after birth (Pang and Ernstrom, 1986). The acidic pH (1.6 ± 0.21) of the abomasum before feeding increased to pH of 6.2 to 6.5, optimum pH of chymosin, immediately after feeding the colostrum (Birģele et al, 2005).…”