DOI: 10.1111/jpn.12338
ORIGINAL ARTICLE
Effect of oral administration of probiotics on growth performance, apparent nutrient digestibility and stress-related indicators in Holstein calves R. Zhang1, M. Zhou1, Y. Tu1, N. F. Zhang1, K. D. Deng2, T. Ma1 and Q. Y. Diao1 1 Feed Research Institute, Chinese Academy of Agricultural Sciences/Key Laboratory of Feed Biotechnology of the Ministry of Agriculture Beijing, China, and 2 College of Animal Science, Jinling Institute of Technology Nanjing, Jiangsu, China
Summary This study aimed to investigate the effect of dietary supplementation with Lactobacillus plantarum and Bacillus subtilis on growth performance, apparent nutrient digestibility and stress-related indicators in dairy calves. Twentyfour neonatal Holstein calves were randomly allocated to three treatments: a basal diet with no supplementation (control), the basal diet supplemented with 1.7 9 1010 CFU per head per day (CFU/h.d) of L. plantarum GF103 (LB group) or the basal diet supplemented with a mixture of L. plantarum GF103 (1.7 9 1010 CFU/h.d) and B. subtilis B27 (1.7 9 108 CFU/h.d) (LBS group). Dry matter intake (DMI), average daily gain (ADG), feed conversation ratio (FCR), apparent digestibility of nutrients and stress-related indicators were measured in this trail. The result indicated that no significant differences were observed in DMI or ADG (p > 0.05), but the FCR was improved in the LB group over the first 12 weeks (p > 0.05). The apparent digestibility of nutrients was not altered by probiotics in week 6 (p > 0.05), but the apparent digestibility of total phosphorus was significantly greater in the LB and LBS groups in week 8 (p > 0.05); additionally, an increase in the apparent digestibility of crude protein was detected in the LBS group (p > 0.05). Oral administration of L. plantarum alone improved the T-lymphocyte transformation rate on days 58 and 62 (p > 0.05), while adding the mixture of L. plantarum and B. subtilis increased the T-lymphocyte transformation rate (p > 0.05) but decreased the content of cortisol on day 58 (p > 0.05). No significant differences were detected between the LB and LBS groups in growth performance, apparent digestibility of nutrients and stress-related indicators (p > 0.05). The results suggested that oral administration of L. plantarum improved growth performance, nutrient digestibility and relieved weaning stress in calves, but no additional effect was obtained by supplementation with B. subtilis. Keywords calves, Lactobacillus plantarum, Bacillus subtilis, growth performance, stress-related indicators, apparent nutrient digestibility Correspondence Prof./Dr. Q. Diao, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China. Tel: +86-10-82106055; Fax: +86-10-821062169105; E-mail: [email protected] Received: 5 February 2015; accepted: 31 March 2015
Introduction The newborn calf is essentially a monogastric animal, and weaning at an early age decreases its resistance to bacterial infections and impairs growth performance (Soderholm and Perdue, 2001). Recent researchers have found that pre-weaning average daily gain (ADG) has positive effects on the long-term productivity of dairy calves, which emphasizes the importance of early nutrition (Soberon et al., 2012; Soberon and Van Amburgh, 2013). Antibiotics are often used to prevent disease and promote growth in pre-weaned calves, but the negative effects are becoming increasingly serious. One of
the promising alternatives to antibiotics is the use of probiotics, as previous studies have shown that probiotics can potentially improve growth performance (Kritas and Morrison, 2005; Frizzo et al., 2010), maintain gastrointestinal microbial balance (Fujiwara et al., 2009; Pieper et al., 2009) and enhance immune function (Nomoto, 2005; Novak et al., 2012). Lactobacilli species have been widely studied (Timmerman et al., 2005; Frizzo et al., 2008), and supplementation with lactic acid bacteria improves the growth performance of calves fed with milk replacer (Frizzo et al., 2011). Bacillus species are the only strains that form spores, which allows themselves to be effective in adverse conditions, and have also
Journal of Animal Physiology and Animal Nutrition 100 (2016) 33–38 © 2015 Blackwell Verlag GmbH
33
R. Zhang et al.
Application of probiotics in calves
attracted increased attention from researchers. It has been reported that oral administration of Bacillus micro-organisms could improve growth performance, feed efficiency and immune response (Hosoi et al., 1999; Sun et al., 2010; Novak et al., 2012). However, the efficacy of combining the above probiotics has rarely been investigated. An in vitro experiment suggested that Bacillus subtilis had the potential, possibly through the production of catalase and subtilisin, to enhance the growth and viability of Lactobacilli (Hosoi et al., 2000). Therefore, additional benefits were expected from the combination of Lactobacillus plantarum and B. subtilis in this trial. In addition, the role of the oral administration of these probiotics in relieving weaning stress in calves was studied for the first time. Material and methods Bacterial preparations
Lactobacillus plantarum GF103 and B. subtilis B27 were isolated from the soil in an animal breeding farm in Da Xing District, Beijing, China. Lactobacillus plantarum GF103 (GenBank Accession number: JQ411248) was cultured in MRS medium at 37 °C for 20 h, and B. subtilis B27 (GenBank Accession number: JQ673431) was cultured in a nutrient broth at 37 °C for 20 h. Following cultivation, 1.0 l of culture medium was mixed with 0.25 kg bran and freeze-dried. The number of viable strains was confirmed by plating serial dilutions of the feed sample on agar plates. As reported by our previous studies, these two kinds of probiotics improved growth performance and enhanced immune responses in weanling piglets (Dong et al., 2013). Animals, treatments and management
Twenty-four male Holstein calves were randomly assigned to one of three treatments immediately after they were born: a basal diet with no supplementation (control), the basal diet supplemented with 1.7 9 1010 CFU/h.d of L. plantarum GF103 (LB group) and the basal diet supplemented with a mixture of 1.7 9 1010 CFU/h.d of L. plantarum GF103 and 1.7 9 108 CFU/h.d of B. subtilis B27 (LBS group). The calves were fed with colostrums and milk at 8% of the birth weight for the first 7 days, and beginning at 8 days of age, a milk replacer was reconstituted into a liquid feed (12.5%, w/v) and fed at 11% of the body weight three times per day. A pellet starter and alfalfa were offered ad libitum from 21 and 28 days of age, respectively, and the refusal was weighed daily. Calves were gradually weaned off the milk replacer 34
from 56 days until 60 days of age. The trial started at 8 days of age and ended at 83 days of age. From 8 to 56 days of age, probiotics were added to the milk replacer prior to the morning feeding. From 56 to 83 days of age, the probiotics were mixed with the pellet feed. The milk replacer was a patented product (patent number: CN02128844.5), while the calf starter was a commercial product. The nutrient profiles of milk replacer and calf starter are shown in Table 1. The experimental protocol was approved by the Animal Ethics Committee of the Chinese Academy of Agriculture Science (Beijing, China). Measurements
Body weight was measured on the first day of weeks 0, 2, 4, 6, 8, 10 and 12 prior to the morning feeding. Daily feed intake of the milk replacer, pellet starter and alfalfa was recorded to calculate the feed conversation ratio (FCR). Digestion trials were performed in both the preweaning (6 weeks of age) and post-weaning (8 weeks of age) periods. Calves were placed in digestion crates for 4 days pre-treatment and 3-day total collection period. Faeces were collected, pooled and weighed daily, 10% of the faecal weight was sampled, and 10 ml HCL (10%) was added to prevent the loss of ammonia. The sample was then dried at 65 °C for 48 h and stored in plastic bags until laboratory analysis. The milk replacer, starter and alfalfa were also sampled and stored in plastic bags for further analysis. Calves were weaned from 56 days of age till 60 days of age, and blood samples were drawn from calves before the morning feeding at 56, 58, 62 days of age; these three sampling days were chosen to detect changes between the pre-weaning, on-weaning and post-weaning periods respectively. Next, 10 ml of blood was collected without anticoagulant and centrifuged at 1300 g for 10 min at 4 °C and the serum was decanted and stored at 20 °C for the subsequent determination of creatine kinase activity (CK activity) and the contents of cortisol and adrenaline (ADR). Another 5 ml of blood Table 1 Chemical composition of the milk replacer and pellet starter feed (air dry basis) Items
Milk replacer
Pellet starter
Dry matter (%) Crude protein (%) Fat (%) Ash (%) Calcium (%) Phosphate (%) Gross energy (MJ/kg)
96.7 21.5 14.5 6.10 1.07 0.522 20.1
91.6 18.1 4.21 7.60 1.09 0.576 17.7
Journal of Animal Physiology and Animal Nutrition 100 (2016) 33–38 © 2015 Blackwell Verlag GmbH
R. Zhang et al.
Application of probiotics in calves
was collected with heparin anticoagulant for the analysis of the T-lymphocyte transformation rate.
differences were found in DMI, ADG and FCR between the LB and LBS groups (p > 0.05).
Chemical analysis
Apparent digestibility of nutrients
The dry matter (DM), organic matter (OM), ether extract (EE), gross energy (GE), crude protein (CP), ash, calcium (Ca) and total phosphorus (P) of the faeces and feed were analysed according to procedures outlined by the AOAC (1990). The DM content was determined by drying at 135 °C for 2 h, and nitrogen was determined with an automatic analyzer (KjellFoss 1620; Foss Electric A/S, Hillerod, Denmark) by the Kjeldahl method. EE was measured by extraction in petroleum ether in a Soxhlet apparatus for 6 h, and ash was determined by complete combustion in a muffle furnace at 600 °C for 8 h. Ca was analysed using an atomic absorption spectrophotometer (M9W-700; Perkin-Elmer Corp., Norwalk, CT, USA), and the total P was determined by the molybdovanadate colorimetric method. The level of CK activity was determined using an automatic biochemical analyzer (HITACHI 7600, Tokyo, Japan). The content of cortisol was measured with an RIA kit (Weifang 3V Diagnostic Biotechnology, Shandong, China) and the concentration of ADR was detected using a commercial ELISA kit (Labor Diagnostika Nord GmbH, Nordhorn, Germany), according to the manufacturer’s instructions. A mitogen-induced lymphocyte proliferation assay was used to determine the proliferation of T cells according to Morrow-Tesch et al. (1994).
No differences were observed in the apparent digestibility of DM, OM, CP, EE, GE, Ca and total P in week 6 (p > 0.05) (Table 3). The apparent digestibility of total P in the LB or LBS group was greater than that of the control in week 8 (p < 0.05), and the apparent digestibility of CP was only improved in the LBS group in week 8 (p < 0.05). No differences were detected in the apparent digestibility of the analysed nutrients between the LB group and the LBS group in either week 6 or 8 (p > 0.05). Stress-related indicators
The level of CK activity, T-lymphocyte transformation rate, and the concentrations of cortisol and ADR are displayed in Table 4. There were no significant differences in the level of CK activity, T-lymphocyte transformation rate, cortisol and ADR at 56 days of age (p > 0.05), but at 58 days of age, the T-lymphocyte transformation rate increased by 48% in both the LB and LBS groups, which was significantly greater than that of the control (p < 0.05). And the concentration of cortisol decreased only in the LBS group (p < 0.05). At 62 days of age, the T-lymphocyte transformation rate improved by 46.3% only in the LB group over that of the control (p < 0.05). Discussion
Statistical analysis
Data of Dry matter intake (DMI), ADG and FCR were analysed as repeated measures, and data of nutrient digestibility and stress-related indicators were analysed by one-way ANOVA. Duncan’s multiple range tests were conducted when a significant difference was detected among means. Statistical significance was determined at p < 0.05 (SAS version 8.01; SAS Institute, Cary, NC, USA). Results Growth performance
Dry matter intake, ADG and FCR are shown in Table 2. There was no effect of the probiotics on DMI and ADG in either the LB or the LBS group over the entire experiment (p > 0.05). Feed conversation ratios (FCRs) in the LB group decreased by 11.47% compared to that of the control (p > 0.05). No significant
Growth performance
Neonatal calves are characterized by high metabolic and rapid growth rates, but their growth performance can be impaired by numerous factors. In this study, the oral administration of probiotics improved FCR over the entire course of the trial, which was supported by previous studies (Timmerman et al., 2005). And the benefits were feed related as the positive effect normally occurred when the calves were fed milk replacer instead of whole milk (Frizzo et al., 2011). Feed conversation ratio is closely connected with the utilization of nutrients; thus, the improved FCR was also consistent with our results regarding the apparent digestibility of nutrients. Apparent digestibility of nutrients
Probiotics had no effect on the apparent digestibility of nutrients before weaning at 6 weeks of age, which
Journal of Animal Physiology and Animal Nutrition 100 (2016) 33–38 © 2015 Blackwell Verlag GmbH
35
R. Zhang et al.
Application of probiotics in calves
Table 2 Dry matter intake, average daily gain and feed conversation ratio of calves over the first 12 weeks Treatment
p Value
Item
CT
LB
LBS
SEM
Treatment
Time
Treatment9Time
Initial weight (kg) Dry matter intake (g/day) Average daily gain (g/day) Feed conversation ratio
42.3 1414 512 2.79a*
42.1 1373 559 2.47b
42.8 1381 549 2.50ab*
1.47 85.0 46.6 0.113
– 0.792 0.549 0.042
–
ORIGINAL ARTICLE
Effect of oral administration of probiotics on growth performance, apparent nutrient digestibility and stress-related indicators in Holstein calves R. Zhang1, M. Zhou1, Y. Tu1, N. F. Zhang1, K. D. Deng2, T. Ma1 and Q. Y. Diao1 1 Feed Research Institute, Chinese Academy of Agricultural Sciences/Key Laboratory of Feed Biotechnology of the Ministry of Agriculture Beijing, China, and 2 College of Animal Science, Jinling Institute of Technology Nanjing, Jiangsu, China
Summary This study aimed to investigate the effect of dietary supplementation with Lactobacillus plantarum and Bacillus subtilis on growth performance, apparent nutrient digestibility and stress-related indicators in dairy calves. Twentyfour neonatal Holstein calves were randomly allocated to three treatments: a basal diet with no supplementation (control), the basal diet supplemented with 1.7 9 1010 CFU per head per day (CFU/h.d) of L. plantarum GF103 (LB group) or the basal diet supplemented with a mixture of L. plantarum GF103 (1.7 9 1010 CFU/h.d) and B. subtilis B27 (1.7 9 108 CFU/h.d) (LBS group). Dry matter intake (DMI), average daily gain (ADG), feed conversation ratio (FCR), apparent digestibility of nutrients and stress-related indicators were measured in this trail. The result indicated that no significant differences were observed in DMI or ADG (p > 0.05), but the FCR was improved in the LB group over the first 12 weeks (p > 0.05). The apparent digestibility of nutrients was not altered by probiotics in week 6 (p > 0.05), but the apparent digestibility of total phosphorus was significantly greater in the LB and LBS groups in week 8 (p > 0.05); additionally, an increase in the apparent digestibility of crude protein was detected in the LBS group (p > 0.05). Oral administration of L. plantarum alone improved the T-lymphocyte transformation rate on days 58 and 62 (p > 0.05), while adding the mixture of L. plantarum and B. subtilis increased the T-lymphocyte transformation rate (p > 0.05) but decreased the content of cortisol on day 58 (p > 0.05). No significant differences were detected between the LB and LBS groups in growth performance, apparent digestibility of nutrients and stress-related indicators (p > 0.05). The results suggested that oral administration of L. plantarum improved growth performance, nutrient digestibility and relieved weaning stress in calves, but no additional effect was obtained by supplementation with B. subtilis. Keywords calves, Lactobacillus plantarum, Bacillus subtilis, growth performance, stress-related indicators, apparent nutrient digestibility Correspondence Prof./Dr. Q. Diao, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China. Tel: +86-10-82106055; Fax: +86-10-821062169105; E-mail: [email protected] Received: 5 February 2015; accepted: 31 March 2015
Introduction The newborn calf is essentially a monogastric animal, and weaning at an early age decreases its resistance to bacterial infections and impairs growth performance (Soderholm and Perdue, 2001). Recent researchers have found that pre-weaning average daily gain (ADG) has positive effects on the long-term productivity of dairy calves, which emphasizes the importance of early nutrition (Soberon et al., 2012; Soberon and Van Amburgh, 2013). Antibiotics are often used to prevent disease and promote growth in pre-weaned calves, but the negative effects are becoming increasingly serious. One of
the promising alternatives to antibiotics is the use of probiotics, as previous studies have shown that probiotics can potentially improve growth performance (Kritas and Morrison, 2005; Frizzo et al., 2010), maintain gastrointestinal microbial balance (Fujiwara et al., 2009; Pieper et al., 2009) and enhance immune function (Nomoto, 2005; Novak et al., 2012). Lactobacilli species have been widely studied (Timmerman et al., 2005; Frizzo et al., 2008), and supplementation with lactic acid bacteria improves the growth performance of calves fed with milk replacer (Frizzo et al., 2011). Bacillus species are the only strains that form spores, which allows themselves to be effective in adverse conditions, and have also
Journal of Animal Physiology and Animal Nutrition 100 (2016) 33–38 © 2015 Blackwell Verlag GmbH
33
R. Zhang et al.
Application of probiotics in calves
attracted increased attention from researchers. It has been reported that oral administration of Bacillus micro-organisms could improve growth performance, feed efficiency and immune response (Hosoi et al., 1999; Sun et al., 2010; Novak et al., 2012). However, the efficacy of combining the above probiotics has rarely been investigated. An in vitro experiment suggested that Bacillus subtilis had the potential, possibly through the production of catalase and subtilisin, to enhance the growth and viability of Lactobacilli (Hosoi et al., 2000). Therefore, additional benefits were expected from the combination of Lactobacillus plantarum and B. subtilis in this trial. In addition, the role of the oral administration of these probiotics in relieving weaning stress in calves was studied for the first time. Material and methods Bacterial preparations
Lactobacillus plantarum GF103 and B. subtilis B27 were isolated from the soil in an animal breeding farm in Da Xing District, Beijing, China. Lactobacillus plantarum GF103 (GenBank Accession number: JQ411248) was cultured in MRS medium at 37 °C for 20 h, and B. subtilis B27 (GenBank Accession number: JQ673431) was cultured in a nutrient broth at 37 °C for 20 h. Following cultivation, 1.0 l of culture medium was mixed with 0.25 kg bran and freeze-dried. The number of viable strains was confirmed by plating serial dilutions of the feed sample on agar plates. As reported by our previous studies, these two kinds of probiotics improved growth performance and enhanced immune responses in weanling piglets (Dong et al., 2013). Animals, treatments and management
Twenty-four male Holstein calves were randomly assigned to one of three treatments immediately after they were born: a basal diet with no supplementation (control), the basal diet supplemented with 1.7 9 1010 CFU/h.d of L. plantarum GF103 (LB group) and the basal diet supplemented with a mixture of 1.7 9 1010 CFU/h.d of L. plantarum GF103 and 1.7 9 108 CFU/h.d of B. subtilis B27 (LBS group). The calves were fed with colostrums and milk at 8% of the birth weight for the first 7 days, and beginning at 8 days of age, a milk replacer was reconstituted into a liquid feed (12.5%, w/v) and fed at 11% of the body weight three times per day. A pellet starter and alfalfa were offered ad libitum from 21 and 28 days of age, respectively, and the refusal was weighed daily. Calves were gradually weaned off the milk replacer 34
from 56 days until 60 days of age. The trial started at 8 days of age and ended at 83 days of age. From 8 to 56 days of age, probiotics were added to the milk replacer prior to the morning feeding. From 56 to 83 days of age, the probiotics were mixed with the pellet feed. The milk replacer was a patented product (patent number: CN02128844.5), while the calf starter was a commercial product. The nutrient profiles of milk replacer and calf starter are shown in Table 1. The experimental protocol was approved by the Animal Ethics Committee of the Chinese Academy of Agriculture Science (Beijing, China). Measurements
Body weight was measured on the first day of weeks 0, 2, 4, 6, 8, 10 and 12 prior to the morning feeding. Daily feed intake of the milk replacer, pellet starter and alfalfa was recorded to calculate the feed conversation ratio (FCR). Digestion trials were performed in both the preweaning (6 weeks of age) and post-weaning (8 weeks of age) periods. Calves were placed in digestion crates for 4 days pre-treatment and 3-day total collection period. Faeces were collected, pooled and weighed daily, 10% of the faecal weight was sampled, and 10 ml HCL (10%) was added to prevent the loss of ammonia. The sample was then dried at 65 °C for 48 h and stored in plastic bags until laboratory analysis. The milk replacer, starter and alfalfa were also sampled and stored in plastic bags for further analysis. Calves were weaned from 56 days of age till 60 days of age, and blood samples were drawn from calves before the morning feeding at 56, 58, 62 days of age; these three sampling days were chosen to detect changes between the pre-weaning, on-weaning and post-weaning periods respectively. Next, 10 ml of blood was collected without anticoagulant and centrifuged at 1300 g for 10 min at 4 °C and the serum was decanted and stored at 20 °C for the subsequent determination of creatine kinase activity (CK activity) and the contents of cortisol and adrenaline (ADR). Another 5 ml of blood Table 1 Chemical composition of the milk replacer and pellet starter feed (air dry basis) Items
Milk replacer
Pellet starter
Dry matter (%) Crude protein (%) Fat (%) Ash (%) Calcium (%) Phosphate (%) Gross energy (MJ/kg)
96.7 21.5 14.5 6.10 1.07 0.522 20.1
91.6 18.1 4.21 7.60 1.09 0.576 17.7
Journal of Animal Physiology and Animal Nutrition 100 (2016) 33–38 © 2015 Blackwell Verlag GmbH
R. Zhang et al.
Application of probiotics in calves
was collected with heparin anticoagulant for the analysis of the T-lymphocyte transformation rate.
differences were found in DMI, ADG and FCR between the LB and LBS groups (p > 0.05).
Chemical analysis
Apparent digestibility of nutrients
The dry matter (DM), organic matter (OM), ether extract (EE), gross energy (GE), crude protein (CP), ash, calcium (Ca) and total phosphorus (P) of the faeces and feed were analysed according to procedures outlined by the AOAC (1990). The DM content was determined by drying at 135 °C for 2 h, and nitrogen was determined with an automatic analyzer (KjellFoss 1620; Foss Electric A/S, Hillerod, Denmark) by the Kjeldahl method. EE was measured by extraction in petroleum ether in a Soxhlet apparatus for 6 h, and ash was determined by complete combustion in a muffle furnace at 600 °C for 8 h. Ca was analysed using an atomic absorption spectrophotometer (M9W-700; Perkin-Elmer Corp., Norwalk, CT, USA), and the total P was determined by the molybdovanadate colorimetric method. The level of CK activity was determined using an automatic biochemical analyzer (HITACHI 7600, Tokyo, Japan). The content of cortisol was measured with an RIA kit (Weifang 3V Diagnostic Biotechnology, Shandong, China) and the concentration of ADR was detected using a commercial ELISA kit (Labor Diagnostika Nord GmbH, Nordhorn, Germany), according to the manufacturer’s instructions. A mitogen-induced lymphocyte proliferation assay was used to determine the proliferation of T cells according to Morrow-Tesch et al. (1994).
No differences were observed in the apparent digestibility of DM, OM, CP, EE, GE, Ca and total P in week 6 (p > 0.05) (Table 3). The apparent digestibility of total P in the LB or LBS group was greater than that of the control in week 8 (p < 0.05), and the apparent digestibility of CP was only improved in the LBS group in week 8 (p < 0.05). No differences were detected in the apparent digestibility of the analysed nutrients between the LB group and the LBS group in either week 6 or 8 (p > 0.05). Stress-related indicators
The level of CK activity, T-lymphocyte transformation rate, and the concentrations of cortisol and ADR are displayed in Table 4. There were no significant differences in the level of CK activity, T-lymphocyte transformation rate, cortisol and ADR at 56 days of age (p > 0.05), but at 58 days of age, the T-lymphocyte transformation rate increased by 48% in both the LB and LBS groups, which was significantly greater than that of the control (p < 0.05). And the concentration of cortisol decreased only in the LBS group (p < 0.05). At 62 days of age, the T-lymphocyte transformation rate improved by 46.3% only in the LB group over that of the control (p < 0.05). Discussion
Statistical analysis
Data of Dry matter intake (DMI), ADG and FCR were analysed as repeated measures, and data of nutrient digestibility and stress-related indicators were analysed by one-way ANOVA. Duncan’s multiple range tests were conducted when a significant difference was detected among means. Statistical significance was determined at p < 0.05 (SAS version 8.01; SAS Institute, Cary, NC, USA). Results Growth performance
Dry matter intake, ADG and FCR are shown in Table 2. There was no effect of the probiotics on DMI and ADG in either the LB or the LBS group over the entire experiment (p > 0.05). Feed conversation ratios (FCRs) in the LB group decreased by 11.47% compared to that of the control (p > 0.05). No significant
Growth performance
Neonatal calves are characterized by high metabolic and rapid growth rates, but their growth performance can be impaired by numerous factors. In this study, the oral administration of probiotics improved FCR over the entire course of the trial, which was supported by previous studies (Timmerman et al., 2005). And the benefits were feed related as the positive effect normally occurred when the calves were fed milk replacer instead of whole milk (Frizzo et al., 2011). Feed conversation ratio is closely connected with the utilization of nutrients; thus, the improved FCR was also consistent with our results regarding the apparent digestibility of nutrients. Apparent digestibility of nutrients
Probiotics had no effect on the apparent digestibility of nutrients before weaning at 6 weeks of age, which
Journal of Animal Physiology and Animal Nutrition 100 (2016) 33–38 © 2015 Blackwell Verlag GmbH
35
R. Zhang et al.
Application of probiotics in calves
Table 2 Dry matter intake, average daily gain and feed conversation ratio of calves over the first 12 weeks Treatment
p Value
Item
CT
LB
LBS
SEM
Treatment
Time
Treatment9Time
Initial weight (kg) Dry matter intake (g/day) Average daily gain (g/day) Feed conversation ratio
42.3 1414 512 2.79a*
42.1 1373 559 2.47b
42.8 1381 549 2.50ab*
1.47 85.0 46.6 0.113
– 0.792 0.549 0.042
–
