The manipulation of rumen fermentation to improve productivity of animals has attracted attention of the researchers for the last two decades and the use of microbial feed additives has been preferred over the chemical or antibiotic feed additives due to several reasons. The use of antibiotics in the ration of livestock is being discouraged or even has been banned in some countries due to their adverse effect on the health of animals, residues left over in the animal products and a risk of creating resistance against these antibiotics. Fuller (1989) reported that live microbial feed supplement beneficially affects the host animal by improving the intestinal microbial balance. The lactobacilli colonize the gut and competitively exclude the pathogenic bacteria (Fuller, 1972). The feeding of lactic acid bacteria has also been reported to increase the mucosal immunity, depending upon the dose of lactic acid bacteria in the diet (Perdigon et al 1990). Keeping in view the above reports, an experiment has been conducted to study the effect of including a mixture of three lactic acid producing bacteria (Lactobacillus acidophilus, L. jugarfi and L. casei) on nutrient utilization, feed conversion efficiency and incidence of diarrhoea in female crossbred young calves fed on grain based and grainless rations.

Thirtytwo crossbred (BOS indicus x Bos taurus) female cattle calves were procured from the Livestock Farms of Indian Veterinary Research Institute, Izatnagar, immediately after colostrum feeding. The animals were distributed into two groups of 16 animals each. One group of animals (G) was fed grain based calf starter (CS1) and the other (Go) was offered grainless calf starter (CS2) along with whole milk and green maize fodder (Table 1). The animals of each group were again divided into two sub groups (culture supplemented, C and culture un-supplemented, Co). The sub-groups (GC and GoC) were fed 100 ml of milk (out of the milk quota assigned to the animals from 0–8 weeks) fermented with lactic acid producing bacteria (Lactobacillus acidophilus, L. jugarti and L. casel) while the animals of the other two sub-groups (GCo and GoCo) were fed unfermented milk as shown in Table 1. Calculated amount of milk as per their body weights was offered to the animals in two doses in the morning and evening at 8.00 and 16.00 hours. Calf starter and green maize were offered individually ad libitum and their intake was recorded daily. Clean drinking water was offered twice daily.

The animals were weighed individually at weekly intervals till 12 weeks of age. One digestibility trial of 6 days duration was conducted after 12 weeks of age. The feed and faecal samples were analysed for proximate principles. For the study of rumen biochemical parameters, the rumen liquor was sampled at 3h post feeding with stomach tube from four animals selected randomly from each of the four groups. The rumen liquor was analysed for pH, total volatile fatty acids (Barnettand Reid, 1957), lactic acid (Barker and Summerson, 1941), and ammonia nitrogen and total nitrogen with the help of Kjeltec auto-analyser.

Pure cultures of three lactic acid producing bacteria (Lactobacillus acidophilus, L, jugarti and L. casei) procured from National Dairy Research Institute, Karnal, were grown on whole milk (cfu of 24h fermented milk varied between 10⁷ to 10⁸/ml) separately and mixed in equal proportions before feeding the animals. All the animals of group GC and GoC were fed 100 ml fermented milk once daily in the morning. After 8 weeks when the milk feeding was stopped, the lactic acid producing bacteria were cultivated in growth medium and fed to animals. The animals of control group were fed an equal quantity of medium without bacterial inoculation.

The experiment continued for a period of 12 weeks. The data were analyzed statistically as per Snedecor and Cochran (1967).

The faeces of animals were examined daily for its consistency, the presence of mucus and periodically examined for the quantitative presence of coliform bacteria. The incidence of diarrhoea was significantly higher in the first 4 weeks of age as compared to 5–8 weeks of age (Fig. 1A). On the feeding of milk fermented with lactic acid producing bacteria there was a reduced incidence of diarrhoea on both the diets tested in this experiment i.e. the concentrate with or without cereal grain. Similarly, the number of days on which the animals showed positive symptoms for diarrhoea was also reduced on both the diets in lactic acid bacteria fed animals (Fig. 1B). The lactic acid bacteria control the growth of coliform bacteria in the gastro-intestinal tract of animals as reported earlier by Ellinger et al (1980) and Kamra et al (1997) either by excretion of antibiotic like substances (Gilliland, 1990) or by competitive exclusion of the pathogenic microbes from the gastro-intestinal tract of the animals (Karney et al 1986).

The chemical composition of milk, feeds and green maize fodder is presented in Table 2. Due to replacement of maize grain with wheat bran, the fibre fraction (neutral detergent fibre and acid detergent fibre) tended to increase in calf starter 2 (CS2) as compared to that in calf starter 1 (CS1).

The dry matter intake, growth and feed conversion efficiency of calves have been presented in Table 3. In the early stage of the life of calves, milk was the major component of the calf's ration. The calves of different groups started eating green maize fodder and calf starter from 2nd and 3rd week of age. The intakes of calf starter and maize increased gradually with the increasing age of the calves and on decreasing the amount of milk offered to the animals. Milk was completely withdrawn from all the calves after 8 weeks of age. The animals of grain replaced groups consumed more concentrate and green fodder in comparison to grain based diets, irrespective of the inclusion of microbial culture, but difference between the groups was statistically non significant. This might be an effort by the animal to increase energy intake to compensate for slightly lower energy content of wheat bran in comparison to that of maize grain. Abu-Tarboush et al (1996) did not find any effect of lactic acid bacteria feeding on dry matter intake whereas Higginbotham and Bath (1993) reported an increase in feed intake of calves on feeding of Lactobacillus acidophilus.

The mean dry matter intake per unit body weight was apparently higher in calves fed grainless ration than those fed grain based concentrates, but differences were not statistically significant. A little less dry matter intake per unit body weight was recorded in probiotic fed groups during the entire feeding trial but the differences were significant only from 8–12 weeks of age. Beckman et al, (1977) and Jenny et al (1991) reported that there was no difference in body weight gain in control and lactic acid bacteria fed animals. In contrast to this Aldrovandi et al (1984) and Abu-Tarboush et al (1996) reported a higher body weight gain due to Lactobacillus supplementation. These differences might be due to different experimental designs, types of animals and feeds used and other unidentified factors which affect the changes in body weight on probiotic feeding.

Mean intake, digestibility of nutrients and nutritive value of feeds are presented in Table 4. There was no significant effect of feeding of grain and probiotic culture on the intake and digestibility of nutrients except the digestibilities of organic matter, neutral detergent fibre and acid detergent fibre, which were significantly higher (P<0.05) in culture supplemented animals fed grainless concentrate, but there was no effect of feeding probiotic on grain based concentrate diet. Similarly Khuntia (1997) also reported increased NDF and hemicellulose digestibility in lactic acid bacteria fed animals.

Rumen liquor samples were collected at 3h post feeding in the 12th week of age and were analysed for changes in pH, total volatile fatty acids, lactic acid, ammonia nitrogen and total nitrogen (Table 5). There was no effect of either grain or lactic culture on any of the rumen biochemical characteristics.

The results indicated that the feeding of lactic acid producing bacteria controls the incidence and intensity of diarrhoea in young calves, especially during the first 4 weeks of age. The feeding of probiotic resulted in a decreased dry matter intake and increased organic matter, NDF and ADF digestibilities (P<0.05) at 12 weeks of age in animals fed grainless concentrate diet. There was no effect of grain or lactic acid bacteria supplementation on body weight gain and feed conversion efficiency upto 12 weeks of age. It is, therefore, concluded that the lactic acid bacteria can be fed to control diarrhoea and grain can be replaced with wheat bran from the diet of crossbred female cattle calves without affecting their productivity.

References