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Probiotics reduce costly problems in calves

Under current husbandry conditions, veal calves are often affected by diarrhoea and respiratory diseases. this becomes particularly problematic when these animals are exposed to stress and change of diet during the first two weeks of life. Research has shown that by balancing the gut of these animals, with the addition of probiotics to the feed, some of these costly problems could be reduced.

Diarrhoea is the main cause of morbidity and mortality in the early life of veal calves. In addition, the first peak of respiratory diseases often emerges at four weeks of age. These two diseases cause substantial economic losses due to medication and growth depression.
Various factors could cause the high incidence of intestinal and respiratory diseases in veal calves. After birth, calves are separated from their mothers. This prevents the calf from acquiring the protective gut microbiota from its mother. Furthermore, at a very young age, the animals are faced with stressful events, like transportation, marketing, dietary changes and exposure to a variety of infectious agents. Consequently, the animals consume less milk and are prone to the loss of the barrier function of the gut and may suffer from impaired immune function. Moreover, the protective potential of the microbial gut microbiota tends to decrease during stressful events, which subsequently increases colonisation of the gut enterobacteriacea.

Multispecies versus Multistrain

To prevent the opportunistic pathogenic flora from flourishing, current practice (in the Netherlands) is to treat calves with prophylactic antibiotics during the first 5 - 10 days after arrival. However, the antibiotics diminish not only the activity of the pathogenic microbiota, but also that of the protective microbiota.

The use of probiotics is promising in establishing a protective microbiota in veal calves. Various papers have addressed the anti-diarrhoeal capacities of different pro-biotic strains in calves. Apart from their positive effects on gastrointestinal infections, probiotics may be used to prevent non-intestinal infectious conditions, such as respiratory tract infections. So far, the effect of probiotics, if any, on respiratory health in veal calves has not been described. To further qualify the health improving capacity of probiotics in young veal calves, the effect of different kinds of probiotics on health and growth variables was investigated. Different probiotic concepts were tested: a multispecies probiotic (MSPB) and a calf specific multistrain probiotic (CSPB). The MSPB preparation contained 6 commercially available probiotic strains of various genera; the CSPB preparation used in this study contained 6 Lactobacillus strains that were originally isolated from veal calf digesta and faeces. It was reasoned that the combination of genera-specific probiotic properties should make the MSPB preparation superior to the traditional monostrain probiotics. It was also hypothesised that the calf specificity of CSPB would enhance the ability of the probiotic product to colonise in the host animal. Because successful colonisation is one of the prerequisites for a probiotic to exert its beneficial activity, it could be suggested that the CSPB should have a greater effect than the MSPB. Furthermore, it should be noted that fresh fermented probiotic cultures were used instead of the common (and more expensive) freeze-dried preparations. The study consisted of four experiments (Table 1 ). In the first two experiments, only the MSPB preparation was tested. The probiotics were administered during the first 14 days after arrival of the calves. In the last two experiments, both the MSPB and CSPB preparations were tested and the period of probiotic administration was extended to 8 weeks.

Increase in growth

Mortality and growth performance are presented in Table 1 . There was no significant effect of probiotic treatment on mortality, growth and FE (feed efficiency) in experiment 1. In experiment 2, there was a lower Average Daily Gain (ADG) from 1 - 8 wk compared with experiment 1. No significant difference occurred regarding mortality, although 4 animals in the control group and 1 animal in the MSPB group died. Treatment with MSPB significantly enhanced growth from 1 - 2 weeks; BW (body weight) gain was 46% higher than in the control animals. This growth-promoting effect of MSPB was still noticeable at week 8; however, it was not statistically significant (NS). No mortality occurred in experiment 3. Calves fed MSPB or CSPB numerically increased BW gain during the first 2 weeks. The probiotic-induced increase of BW gain was not statistically significant, although a significant improvement of FE for 1 - 2 weeks was observed (data not shown). No significant differences regarding BW gain and FE were seen for week 1 - 8. There was a carryover effect of probiotic treatment in that it reduced digestion problems during the last phase of the 26-week fattening period and lowered the FE from week 20 - 27 (data not shown). The result was a 4.0kg and 4.1kg higher carcass weight for the CSPB- and MSPB-treated animals, respectively. The increase in carcass weight was not statistically significant. There was no mortality in experiment 4. BW gain was low compared with that found in experiments 1, 2 and 3. Both probiotic treatments markedly enhanced BW gain. The growth-promoting effect of CSPB was statistically significant for week 1 - 2 and 1 - 4, whereas MSPB treatment significantly increased BW gain for week 1 - 4 and 3 - 4. The growth-promoting effect was still present for week 1 – 8 (NS). Feed efficiency over the 8-week period numerically decreased after treatment with MSPB or CSPB (-18% and -17%; NS). When all the data was pooled, probiotic treatment was associated with significantly enhanced growth during the first 2 weeks and in the periods 1 - 4 and 1 - 8 weeks of the starter phase. BW at 8 weeks was significantly higher after probiotic treatment. Average daily gain and FE from week 1 - 8 was significantly improved after feeding probiotics (+2.6% and -6.7%). Furthermore, probiotic treatment tended to lower mortality.

Effect on diarrhoea incidence and duration

In experiment 2 and 4, a distinction was made between mild and severe diarrhoea. There was a low incidence of diarrhoea in experiment 1 compared with the other experiments. Treatment with MSPB caused a reduction in average duration of diarrheic episodes (NS; data not shown). In experiment 2, the number of days with mild diarrhoea was high. Treatment with MSPB resulted in a non-significant increase. In experiment 3, treatment with either MSPB or CSPB reduced the incidence of diarrhoea. The CSPB, unlike MSPB, diminished the duration of diarrhoea. In experiment 4, CSPB treatment successfully suppressed mild diarrhoea compared with the calves treated with MSPB and the control calves. Administration of MSPB had no significant influence on mild diarrhoea. Both MSPB and CSPB treatment lowered the incidence of severe diarrhoea (NS). Treatment with CSPB significantly lowered the incidence and duration of diarrhoea (-50% and -58%), irrespective of its nature. In experiments 3 and 4, faecal samples were taken to enumerate the number of faecal lactobacilli and coliforms on day 5, 12 and 50 after arrival of the calves. The numbers were generally higher in experiment 3 than in experiment 4. There was no effect of either probiotic on the number of faecal lactobacilli. Coliform concentrations in the faeces tended to be decreased with probiotic treatment. Treatment with CSPB reduced the average number of coliforms on day 5 by 14% and 57% (P < 0.05) in experiment 3 and 4, respectively. Only in experiment 4 did the CSPB treatment significantly reduce the average faecal coliform population. Treatment with MSPB did not affect coliforms in experiment 3; however, a small, non-significant reduction was seen in experiment 4 on day 5 and 12.

Digestive and respiratory diseases

The lowest percentage of animals that needed therapeutic treatment of digestive diseases, and for all infections combined, was seen in experiment 1. Treatment with MSPB resulted in a lower percentage of animals being treated for digestive diseases and a lower number of treatments (NS). There was a high incidence of digestive and respiratory diseases in experiment 2. Treatment with MSPB did not elicit a clear influence on treatments for digestive or respiratory diseases. In experiment 3, the control animals had a high incidence of gastrointestinal infections and a low incidence of respiratory diseases. Treatment with MSPB successfully reduced the percentage of animals suffering from digestive diseases and the number of treatments needed (P < 0.05). Overall, MSPB significantly reduced the percentage of animals in need of therapeutic treatment for any reason, as well as the average amount of treatments needed. In experiment 4, the incidence of digestive diseases was moderate. Both MSPB and CSPB numerically lowered the percentage of animals treated and the average number of treatments needed. In experiment 4, both MSPB and CSPB significantly reduced the incidence of respiratory disease and its severity as expressed by the number of total treatments needed per affected animal (data not shown). Treatment with MSPB or CSPB significantly reduced the percentage of animals in need of therapeutic treatment of any cause and reduced the total number of treatments needed (-72% and -57%, respectively).

Effect on GHS

During the experiments, the General Health Score (GHS) of all the calves was calculated. A low GHS may be associated with high infection pressure and could cause diarrhoea, respiratory diseases and other infectious diseases, as well as high mortality. Health was significantly compromised in experiment 4 compared with calves in the other experiments. In experiment 1, the GHS was relatively high indicating a low infection pressure. Excluding experiment 1, probiotics numerically raised the GHS. In experiment 2 and 3, treatment with either probiotic improved the GHS to a similar extent (NS). Animals in experiment 4 showed the lowest GHS. In this situation, treatment with either probiotic resulted in a marked improvement of the GHS (P < 0.01). When all the data was pooled, probiotic treatment was found to be associated with a significantly improved GHS. It could be suggested that the stimulatory effect of probiotic treatment on growth depends on the baseline GHS. Indeed, the GHS of control calves and the MSPB-induced increase in ADG during week 1 - 8 were negatively related when the data of the 4 experiments was pooled. Thus, the higher the GHS of control calves, the lower the MSPB-induced increase in weight gain.

Conclusion

It is clear from this study in 1-week-old veal calves that administration of probiotics may increase BW gain during the first 2 weeks of use. The probiotic-induced increase in BW gain for the period of 1 - 8 weeks was greater when the calves were considered less healthy. Thus, the positive effect of probiotics on growth performance of calves may only be present when their health status is compromised. BW and feed efficiency at 8 weeks after arrival were significantly improved by probiotic treatment. Probiotic treatment reduced the incidence of diarrhoea and the average number of diarrheic days. Mortality tended to be lower after feeding a milk replacer with probiotics. Although there were differences in outcomes between experiments, it can be concluded that the supply of probiotics reduced the necessity of antibiotic treatments against digestive and respiratory diseases. Further experiments are required to study underlying mechanisms and to evaluate the potential of probiotics to improve respiratory health in veal calf production.

About the Author
Harro Timmerman graduated in animal sciences from Wageningen University in 1999. in 2000, he began a PhD at Winclove Bio Industries BV (www.winclove.nl) on the health promoting effects of probiotics in livestock. this study has been carried out in cooperation with Schothorst feed research, the faculty of animal nutrition at Utrecht University, the laboratory of food microbiology at Wageningen University and several feed companies. In 2006, Timmerman successfully completed his PhD thesis: Multispecies probiotics – composition and functionality.


Source: Feed Mix magazine Volume 15 nr.1

Editor AllAboutFeed

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