Effects of castration and weaning conducted concurrently or consecutively on behaviour,blood traits and performance in beef calves

The objectives of this study were to evaluate the effects of Burdizzo castration and abrupt weaning on the behaviour, blood traits and performance of beef calves when weaning was conducted concurrently or consecutively to castration. In total, 64 male beef calves aged between 6 and 7 months were assigned to a 2×2 factorial design with the following treatment groups (n=16 animals per treatment): (1) castrated and concurrently weaned in week 0 (CAS-WEA); (2) castrated in week 0 and weaned in week 4 (CAS-CON); (3) bulls weaned in week 0 (BUL-WEA); and (4) bulls weaned in week 4 (BUL-CON). The behaviour of the calves was observed for 3 days following weaning. Blood was collected weekly from weeks 0 to 5 and analysed for the acute-phase protein haptoglobin, and neutrophil and lymphocyte percentages. BW was recorded weekly from weeks 0 to 7. Animals were slaughtered at 17 months and weight, dressing percentage and carcass classifications were recorded. On day 1 after weaning, the number of vocalizations (calls/10 min) was higher in BUL-WEA (7.2) and CAS-WEA (5.4) than in calves of CAS-CON (2.8) and BUL-CON (2.9) groups (P<0.05). From days 1 to 3 vocalizations decreased in all groups. CAS-CON and BUL-CON animals spent 20% lying on day 1 after weaning compared with 40% in CAS-WEA and BUL-WEA calves (P<0.05). The haptoglobin concentration decreased during the first 5 weeks after weaning in all groups independent of the castration, weaning group or its interaction (P>0.05). WEA groups showed an increased average daily gain (ADG) during weeks 0 to 3 and a reduced ADG during 4 to 7 weeks in comparison with CON animals. At slaughter, bulls were about 80 kg heavier than castrates and had a superior dressing percentage and carcass classification (P>0.05). In conclusion, weaning had a greater effect on the number of vocalizations, standing/walking and lying behaviour and ADG compared with Burdizzo castration. In comparison with undertaking the procedures separately, concurrent castration and weaning neither affected behaviour and haematological parameters nor impaired performance. There was no evidence that the concurrent application of both treatments markedly increased the stress response compared with their application at intervals of a few weeks.     

Occurrence of enterotoxigenic and nonenterotoxigenic Bacteroides fragilis in calves and evaluation of their antimicrobial susceptibility

Bacteroides fragilis is considered an important clinical pathogen and the most common anaerobe isolated from human and animal clinical specimens; enterotoxigenic strains produce diarrhea. The presence of enterotoxigenic (ETBF) and nonenterotoxigenic B. fragilis in stool samples from calves with or without acute diarrhea and the antimicrobial susceptibility of the strains were evaluated. The stool samples were plated onto a selective B. fragilis-bile-esculin agar, and incubated anaerobically (10% CO(2)/90% N(2)), at 37 degrees C, for 72 h. Species of the B. fragilis group were identified by using the API 32-A kit. Enterotoxigenic strains were detected by PCR and the cytotoxic assay. From 54 diarrhea and 54 nondiarrhea stools, 124 and 92 members of the B. fragilis group, respectively, were recovered. Only two ETBF strains were isolated from two different diarrhea samples and the bft gene was detected in both. Moreover, the bft gene was detected in DNA from four different diarrheal stools samples but no ETBF strain was recovered. All the bacteria were susceptible to chloramphenicol, imipenem, moxifloxacin, piperacillin/tazobactam, metronidazole and tigecycline. Most of the isolates from both calves with and without diarrhea were resistant to all metals. Our results are of concern, and suggest the need to increase the surveillance of antibiotic and metal resistance of this microbial group isolated from animal production such as calves.     

Effect of dam factors on milk intake and performance of Belgian Blue suckling calves

Milk intake data were collected at 4-week intervals from Belgian Blue double-muscled (BBDM) suckling calves up to 16 weeks after birth. Dams were fed at 100%, 90%, 80% or 70% of their energy requirements during a 140-day indoor period from the beginning of December to the end of April (restriction period). Afterwards, cows were turned out on pasture (re-alimentation period). Mean calving date was 3 June, but parturitions were spread over the year. A total of 521 individual milk intake (IMI) and 120 average daily milk intake (AMI, mean of IMI) records were collected. IMI amounted to 7.0 ± 2.2 kg/day and was not affected by energy level during the indoor period. It was highest in May and June. Calves born out of multiparous cows consumed more milk than those born out of primiparous cows (7.4 v. 6.2 kg per day; P = 0.001), while intake tended to be higher in female than in male calves (7.2 v. 6.8 kg per day; P = 0.044). Dam age at calving, parity, post partum weight and body condition were only weakly correlated with AMI (r 0.4). AMI was correlated with pre-weaning live-weight gain (r = 0.807) and weaning weight (r = 0.783), with a slightly higher correlation for male than for female calves. Daily live-weight gain during the suckling period was increased by 79 g per extra kg daily milk intake on average, and by 86 and 74 g, respectively, for male and female calves. Calf solid feed intake was low, even when milk intake was low. In terms of net energy intake, milk was only substituted for solid feed by 29%. It can be concluded from the calf intake that milk production in BBDM cows is comparable with that of cows from other beef breeds, but its variation is considerable, complicating an accurate estimation.     

Design of a beneficial product for newborn calves by combining Lactobacilli,minerals, and vitamins

Diarrhea is one of the most frequent diseases affecting newborn calves in intensive systems. Several strategies were proposed to protect and improve health, such as probiotics. This work was directed to design a product containing freeze-dried bacteria, vitamins, and minerals, as well as to optimize conditions with lyoprotectors, combine strains and add vitamins, minerals, and inulin to the product. The lyoprotectors were milk, milk-whey, and actose, and products were stored for 6 months at 4°C. Combined bacteria were freeze-dried in milk and the final products were added with minerals, vitamins, and insulin. The viable cells were determined by the plate count assay and antibiotic profiles to differentiate strains. Lactobacillus johnsonii CRL1693, L. murinus CRL1695, L. mucosae CRL1696, L. salivarius CRL1702, L. amylovorus CRL1697, and Enterococcus faecium CRL1703 were evaluated. The optimal conditions were different for each strain. Milk and milk whey maintained the viability during the process and storage after 6 months for most of the strains, except for L. johnsonii. Lactose did not improve cell’s recovery. L. murinus was viable for 6 months in all the conditions, with similar results in enterococci. In strains combined before freeze-dried, the viability decreased deeply, showing that one-step process with bacteria mixtures, vitamins, and minerals were not adequate. Freeze-dried resistance depends on each strain and must be lyophilized individually.     

Detection of heat-stable and heat-labile enterotoxin genes of Escherichia coli in diarrhoeic faecal samples of mithun (Bos frontalis) calves by polymerase chain reaction

Aims:  To find out the prevalence of different serogroups of Escherichia coli ( E. coli ) and to detect heat-stable (ST) and heat-labile (LT) enterotoxin genes of enterotoxigenic E. coli (ETEC) from the faeces of mithun calves with diarrhoea.
Methods and Results:  Faecal samples obtained from 65 diarrhoeic mithun calves of under 2 months of age were examined for E. coli using polymerase chain reaction (PCR). Fifty-four E. coli isolates were obtained from those samples, which belonged to 38 different serogroups. Out of 54 isolates tested by PCR, two isolates (3·70%) belonging to serogroups O26 and O55 were found to possess gene that code for ST enterotoxin and one isolate (1·85%) belonging to serogroup O125 was found to carry LT enterotoxin gene.
Conclusions:  Escherichia coli isolates from diarrhoeic mithun calves were found to possess ST and LT enterotoxin genes, which are designated as ETEC, and these isolates can be detected through PCR using specific primers.
Significance and Impact of the Study:  This study reports the isolation of ETEC possessing ST and LT enterotoxin genes for the first time and ETEC could be a cause of diarrhoea in mithun calves leading to calf mortality.     

Effects of long period feeding pistachio by-product silage on chewing activity,nutrient digestibility and ruminal fermentation parameters of Holstein male calves

The objective of this study was to determine the effects of pistachio by-product silage (PBPS) as a partial replacement for corn silage (CS) on chewing activity, nutrients digestibility and ruminal fermentation parameters in Holstein male calves over a 6-month assay. For this purpose, 24 Holstein male calves (4 to 5 months of age and 155.6±13.5 kg BW) were randomly assigned to one of the four dietary treatments (n=6). In these treatments, CS was substituted with different levels of PBPS (0%, 6%, 12% and 18% of dry matter (DM)). Nutrient digestibility was measured at the end of the experimental period (days 168 to 170). Ruminal fermentation parameters were determined on days 90 and 180 and chewing activity was determined on days 15 of the 3^rd and 6^th month of the experiment. Results showed that calves fed rations containing 6% PBPS spent more time ruminating (P<0.05) than the control group on the 3^rd and 6^th months. Feeding PBPS was found to have no effects on DM, organic matter (OM), ether extract or ash digestibility, but apparent digestibility of CP, NDF_om and ADF_om linearly decreased (P<0.01) with increasing substitutions. On days 90 and 180, ruminal concentrations of volatile fatty acids and NH₃–N linearly decreased (P<0.01) with increasing levels of PBPS in the diets; however, ruminal pH and molar proportions of acetate, propionate and butyrate were similar across the treatments. It was concluded that partial substitution of CS with PBPS (6% or 12%) would have no adverse effects on nutrient digestibility, total chewing activity and ruminal fermentation parameters.     

麋鹿幼仔的活动同步性与同性聚群倾向

哺乳动物幼体从出生到性成熟这段时间存在生理和行为上的巨大变化.麋鹿幼仔出生1周内,与成鹿和其它仔鹿呈隔离状态,且藏卧于隐蔽处,母鹿哺乳是引起幼仔活动的主要因素.     

Isolation of bovine intestinal Lactobacillus plantarum and Pediococcus acidilactici with inhibitory activity against Escherichia coli O157 and F5

Aims:  The growth rate of bovine lactic acid bacteria (LAB) in five different culture conditions, and their inhibitory activity against Escherichia coli O157 and F5 in two assays was assessed to identify LAB for potential prophylactic use in cattle.
Methods and Results:  106 bovine-derived faecal/intestinal LAB were tested in vitro for tolerance to pH 2·0, pH 4·0, 0·15% and 0·3% bile, aerobic incubation, and for inhibitory activity against E. coli O157 ( n  = 3) and F5 ( n  = 1). While no LAB grew at pH 2·0, LAB survivability varied between 35% and 100% on the other tests. Exactly 7·6% (8/106) of LAB supernatants inhibited the growth of E. coli in two assays, whereas 6·6% (7/106) of isolates enhanced the growth of all E. coli strains. Partial 16s rRNA gene sequencing of six best isolates (95th percentile) revealed that five were Lactobacillus plantarum and one Pediococcus acidilactici.
Conclusion:  Lactobacillus plantarum with acid/bile and aerobic resistance and inhibitory activity against E. coli O157 and F5 inhabit the intestinal tract of healthy cattle. Some LAB may enhance E. coli growth.
Significance and Impact of the Study:  Lactobacillus plantarum and P. acidilactici are natural plant micro-organisms and studied silage inoculants. Their identification from gastrointestinal samples of healthy cattle is prophylactically promising.     

Effects of isovalerate supplements on morphology and functional gene expression of rumen mucosa in pre- and post-weaning dairy calves

Isovalerate supplements could stimulate rumen development by improving morphology and function of rumen mucosa, and then promote the growth of calves. This study was done to evaluate the effects of isovalerate supplements on morphology and functional gene expression of rumen mucosa in dairy calves. In total, 48 Chinese Holstein male calves with 15 days of age and 45.1±0.36 kg of BW were randomly assigned to four groups. The treatments were: control, low-isovalerate, moderate-isovalerate and high-isovalerate with 0, 3, 6 and 9 g isovalerate per calf per day, respectively. Supplementary isovalerate was hand-mixed into milk in pre-weaning calves and into concentrate portion in post-weaning calves. The study consisted of a 15-day-adaptation period and a 60-day-sampling period. Calves were weaned at 60 days of age. Three calves were slaughtered from each of the four treatments at 30, 60 and 90 days of age. The weight of body and stomach were measured, samples of ruminal tissues and blood were analyzed. Total stomach weight, total stomach to BW ratio, rumen wall and keratinized layer thickness, serum growth hormone and IGF-1 for both pre- and post-weaning calves increased linearly with increasing isovalerate supplements. Rumen to total stomach weight ratio, the length and width of rumen papillae, and serum β-hydroxybutyrate increased linearly for post-weaning calves. However, abomasum weight to total stomach weight ratio decreased linearly for both pre- and post-weaning calves. The relative messenger RNA expression for growth hormone receptor, IGF-1 receptor and 3-hydroxy-3-methylglutaryl-CoA synthase 1 in rumen mucosa increased linearly for post-weaning calves. Our results suggested that isovalerate supplements promoted rumen development in a dose-dependent manner. The optimum dose was 6.0 g isovalerate per calf per day.