Effects of probiotics on growth performance in young calves: A meta-analysis of randomized controlled trials
Introduction
Lactic acid bacteria (LAB) are in the normal intestinal microbiota of animals and humans (Schneider et al., 2004, Soto et al., 2010), and have been identified as controllers of pathogens such as Salmonella spp. (Gill et al., 2001) and Escherichia coli (Shu and Gill, 2002). These pathogens are the etiologic agent of calf diarrheas during the first weeks of life, and diarrhea is the main cause of morbidity and mortality in the early life of calves (Timmerman et al., 2005).
It is very important to reduce the prevalence of gastrointestinal infections in young calves, because when animals are ill at this stage, their subsequent growth is delayed thereby affecting productivity (Rosmini et al., 2004). The high incidence of intestinal disease is especially high in intensive rearing systems where exposure to pathogens is increased due to confinement of large numbers of animals in small areas (Callaway et al., 2002).
Use of LAB to reduce pathogenic bacteria in the gut has been termed a probiotic strategy, with an overall goal of promoting colonization of protective bacteria in calves during the first weeks of life to compete with pathogenic bacteria. Additionally, LAB can stimulate development of the immune response against pathogenic bacteria and counteract negative effects of illnesses (Frizzo et al., 2010).
To prevent and control intestinal infections, a current practice is to use antibiotics, a strategy which could increase the emergence and spread of antibiotic-resistant bacteria in meat and dairy products. In addition, residual antibiotics in those foods are unacceptable for human consumption. To overcome these problems, use of LAB has been suggested as a feed additive to promote beneficial effects to the host by favoring the balance of the intestinal microbiota (Abu-Tarboush et al., 1996).
Reports of LAB fed to young calves are inconclusive. Many authors reported beneficial effects of probiotic preparations on animal growth (Abe et al., 1995, Meyer et al., 2001, Timmerman et al., 2005, Frizzo et al., 2008, Frizzo et al., 2010), while others (Jenny et al., 1991, Higginbotham and Bath, 1993, Abu-Tarboush et al., 1996, Cruywagen et al., 1996, Goncalves et al., 2000) reported no effects.
Systematic review consists of a scientific technique of reviewing available literature using explicit methods to identify, select and critically evaluate studies which are relevant to the stated objective (Faria Filho et al., 2006). A consistent review of studies of probiotics added to calves diets and published to date can be completed using meta-analyses. As the use of probiotics in the diet of young calves may improve their growth performance, the objective of this meta-analysis was to assess effects of probiotic supplementation on growth performance (e.g., body weight gain (BWG), feed efficiency) in young calves.
Section snippets
Criteria for study selection
The studies included in the meta-analysis were selected based on the criteria: randomized and controlled experiments, studies which used calves <10 d of age, without diseases and with passive immunity, and published in peer-reviewed journals. Controlled experiments were defined to include use of a placebo. LAB could be added in whole milk, pasteurized whole milk, or milk replacer and with or without inclusion of a calf starter as a solid diet. All feeds used must have been free of added
Overview of included studies
The literature search yielded 66 scientific papers on probiotics and calves. Twenty one of the 66 screened articles met all inclusion criteria to assess the probiotic effect on BWG, but only 14 articles were included in the evaluation of the probiotic impact on feed efficiency.
Within the studies included to assess the probiotic effect on BWG in young calves, only one study was conducted before 1990, with most between 1991 and 2000 (11) and after 2001 (9). Holstein calves were used in the most
Discussion
This quantitative meta-analysis of data from several randomized controlled experiments showed that probiotic supplementation increased BWG and feed efficiency in young calves.
Conclusions
This meta-analysis included a large number of experiments which assessed growth performance of calves and showed that supplementation with LAB is effective in improving BWG and feed efficiency, especially during the first 60 d of rearing in calves fed milk replacer. The probiotic effect was not related to supplementation with monostrain or multistrain inocula. A beneficial effect on feed efficiency was associated with experiments which used >20 calves, while the effect on BWG was identified with
Acknowledgments
Laureano S. Frizzo and Lorena P. Soto are posdoctoral fellows and Marcelo L. Signorini is a Research Career Member from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Argentina). María V. Zbrun is doctoral fellow from the Universidad Nacional del Litoral (Argentina).
References (41)
- et al.
Effect of administration of Bifidobacteria and lactic acid bacteria to newborn calves and piglets
J. Dairy Sci.
(1995) - et al.
Evaluation of diet containing Lactobacilli on performance, fecal coliform, and Lactobacilli of young milk calves
Anim. Feed Sci. Technol.
(1996) - et al.
Effect of Lactobacillus acidophilus supplementation of milk replacer on preweaning performance of calves
J. Dairy Sci.
(1996) - et al.
Lactic acid bacteria to improve growth performance in young calves fed milk replacer and spray-dried whey powder
Anim. Feed Sci. Technol.
(2010) - et al.
Evaluation of Lactobacillus fermentation cultures in calf feeding system
J. Dairy Sci.
(1993) - et al.
Effect of a direct feed microbial product on calf performance and fecal flora
Prof. Anim. Scientist
(1998) - et al.
Improvement of intestinal microflora balance and prevention of digestive and respiratory organ diseases in calves by green tea extracts
Livest. Prod. Sci.
(2001) - et al.
Performance and fecal flora of calves fed a Bacillus subtiliis concentrate
J. Dairy Sci.
(1991) - et al.
Invited review: use of meta-analysis in animal health and reproduction: methods and applications
J. Dairy Sci.
(2009) - et al.
Immune protection mediated by the probiotic Lactobacillus rhamnosus HN001 (DR20™) against Escherichia coli O157:H7 infection in mice
FEMS Immun. Med. Microbiol.
(2002)
Health and growth of veal calves fed milk replacers with or without probiotics
J. Dairy Sci.
Efficacy of a probiotic added to whole milk and to a milk substitute
Rev. Med. Vet.
Use of probiotic with Lactobacillus acidophilus, Streptococcus faecium and Sacharomyces cerevisae in veal calves diet: effects on performance and meat quality
Braz. J. Vet. Res. Anim. Sci.
Effect of probiotic and milk feeding frequency on performance of dairy Holstein calves
Int. J. Dairy Sci.
Intestinal microbiota and the interaction with immunocompetent cells
Anton. Leeuw.
Operating characteristics of rank correlation test for publication bias
Biometrics
Sodium chlorate supplementation reduces E. coli O157:H7 populations in cattle
J. Anim. Sci.
Effect of one strain of Lactobacillus acidophilus (LT 516) as probiotic for calves
Rev. Bras. Zootec.
Veterinary Epidemiologic Research
Bias in meta-analysis detected by a simple, graphical test
Br. Med. J.
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