Ultrasonography to investigate the effect of supplementing whole milk with complex carbohydrates and specific amino acids on curd retention in the abomasum of dairy calves

AIM: 1) To determine if ultrasonography can be used to evaluate the abomasal residence time of curd; 2) To investigate if the transit time of curd is influenced by a supplement of plant-derived complex carbohydrates and specific amino acids to whole milk. METHODS: Trial 1 was carried out with pre-ruminant dairy heifer calves (n=10) to determine if ultrasonography can detect the formation of curd in the abomasa after feeding whole milk. In Trial 2 , 22 calves were fed whole milk until weaning (4 litres per day using an automated feeder), and 21 calves were fed whole milk supplemented with a probiotics until 18 days of age, and thereafter with plant-derived complex carbohydrates and amino acids until weaning. The groups were balanced for age, weight and breed. At 2, 4 and 8 weeks of age, ultrasonography was conducted immediately before feeding, 1 and 2 h after feeding, and then at 30 min intervals until curd was no longer visible. RESULTS: In Trial 1, a score scale was established to evaluate the volume and size of curd and to monitor the clearance time from the abomasa. In Trial 2, at 2 weeks of age, supplementing whole milk with the probiotics did not affect retention time compared with calves fed whole milk alone. However, at 4 weeks of age, by which time the calves in the supplement group had been fed the carbohydrate and amino acids supplement for one and a half weeks, curd remained in the abomasa of calves in the supplement group for 1.4 h longer (p<0.001) than the group fed milk alone. Close to weaning (8 weeks of age), the calves fed the carbohydrate and amino acid supplement retained curd in the abomasum for 0.7 h longer (P=0.05) than the calves fed whole milk alone. CONCLUSION: These data demonstrate that ultrasound is an informative, non-invasive method for monitoring the formation of curd and the rate of transit from the abomasa of pre-ruminant calves. The probiotics are not expected to alter the formation of curd. Thus, the similarity in transit time between the two groups during the probiotic feeding phase was expected. However, the plant-derived complex carbohydrate and amino acid supplement delayed the transit time from the abomasum. Therefore, this supplement may increase the assimilation of nutrients and, thereby, growth of calves.