营养因素对犊牛疾病及免疫的影响

犊牛在应激时对于呼吸系统综合病等疾病的易感性增加，通过调整日粮中的营养因素水平、比例等可增强犊牛的免疫力和抗病力。本文对日粮中的能量水平、维生素和矿物质等对犊牛疾病及免疫的影响等方面进行了概述。     

Behaviour of early-weaned calves in indoor individual cubicles and group pens

Extract

Units have been designed to house calves for veal production, but only recently has a large intensive unit been designed to rear surplus dairy-bred calves for beef production in New Zealand. This was built by the Rangitaiki Plains Dairy Company, Edgecumbe, early in 1973 and consisted of two types of housing: a fully enclosed and insulated calf house with 500 individual cubicles in which to rear the animals till weaning at 5 weeks of age, and a “loafing barn” with slatted walls and sawdust floor to house calves for a further 5 weeks before sale as beef weaners.     

Comparison of injuries in sows housed in gestation stalls versus group pens with electronic sow feeders

OBJECTIVE: To compare the location and severity of injuries in pregnant sows housed in individual gestation stalls with that in pregnant sows housed in dynamic groups in pens with electronic sow feeders. DESIGN: Prospective study. ANIMALS: 100 pregnant sows of parity 1 to 3 and various body weights. PROCEDURE: Fifty sows each were randomly allotted to gestation stalls or group pens with electronic sow feeders. Injuries were scored on the basis of location, number, and depth of wounds. Injury scores for sows in both housing systems were compared during a period of 90 days. The influence of factors such as duration of stay in the housing system, parity, and body weight on sow injuries was also examined. RESULTS: Injury scores were higher in group pens with electronic sow feeders. As body weight increased, injury scores decreased for sows housed in group pens with electronic sow feeders and increased for sows housed in gestation stalls. There was a significant negative association between second parity and total injury scores. CONCLUSIONS AND CLINICAL RELEVANCE: Modifications in housing system design and management procedures are needed to reduce injuries in pregnant sows.     

The effect of claw trimming on the hoof health of Swedish dairy cattle

A 2-year experiment on the effect of claw trimming on hoof health was performed in 77 Swedish dairy herds (3444 dairy cattle) selected on herd size, breed composition and membership in the official milk-recording scheme. In the autumn, cows within each herd were blocked according to breed, parity and stage of lactation and allocated to two treatments: autumn trimming (AT) or no autumn trimming (NAT). Outcome variables were claw measurements and prevalence of hoof lesions and lameness (measured at spring trimming) and the need for hoof treatments between scheduled trimmings. At spring trimming, NAT cows had longer and shallower claws than AT cows. The average net growth of the toe wall was greater for AT than for NAT cattle, with a marked variation between housing systems. Most hoof lesions present at AT had disappeared at the subsequent spring trimming. Controlled for clustering by herd-within-year and for the effects of individual-and herd-level covariates, AT cattle at spring trimmings had significantly lower odds of lameness (OR=0.66) and of haemorrhages of the sole or white-line (OR=0.86), sole ulcer (OR=0.59) and white-line fissure or double sole (OR=0.71)-but not of moderate-to-severe heel-horn erosion or dermatitis (OR=0.96). Acute hoof treatments between claw trimmings were more common in the NAT group (OR=2.02).     

Dam-related effects on heart girth at birth,morbidity and growth rate from birth to 90 days of age in Swedish dairy calves

We investigated the effects of dam-related factors (such as calving performance, milk leakage, diseases, milk production, and somatic-cell count (SCC)) on heart girth at birth and the incidence risk of diarrhoea and respiratory disease during the first 90 days in Swedish dairy calves. The effects of these dam-related factors and environmental and management-related (but not dietary) factors on the calves' growth rate during the first 90 days of life also were analysed. The study used nearly 3,000 heifer calves born in 1998 on 122 farms in the south-west of Sweden. Individual health records were kept by the farmers and visiting project veterinarians. The calf's heart girth was measured at birth and weaning. We used generalised linear mixed models for the size of the calf at birth and growth rate. Variables associated with the heart girth at birth were breed, calving performance, mastitis in the dam in the last 49 days before calving, milk production and parity. Variables associated with the growth rate were breed, calving performance, disease in the calf during its first 90 days of life, heart girth at birth, and housing of calves. The effect of the dam on the relative risk of diarrhoea and/or respiratory disease in the calf was evaluated by a generalised linear mixed model with a logit link. Morbidity in the dam during late pregnancy, retained placenta and SCC were associated with the relative risk of respiratory disease in the calf. None of the explanatory variables (other then breed) was associated with the relative risk of diarrhoea.     

Hygiene management in newborn individually housed dairy calves focusing on housing and feeding practices

In calf rearing, the first weeks of life are critical and associated with the highest mortality due to enteric and respiratory diseases. A well-implemented hygiene management can help to protect calves’ health preventively by reducing the load of pathogenic bacteria and interrupting infection chains. The aim of this study was to identify deficiencies in hygiene management of individually housed dairy calves by surveying current practice and examining feeding and housing equipment with different hygiene indicators. On 11 farms, different locations in 2 pens or hutches for individual calf rearing prepared for restocking and 2 feeding buckets per farm, including the inner and outer surfaces of artificial teats, were visually scored for cleanliness and sampled with swabs (housing equipment: n = 167; feeding equipment: n = 120). The sanitation of floors was tested with sock samples (n = 41). A total of 328 samples were analyzed for adenosine triphosphate (ATP) and protein residues, aerobic total viable count (TVC), total coliform count (TCC), Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum β-lactamase-producing bacteria (ESBL), and Salmonella spp. After evaluation of these results, the farmers were informed about the findings and trained on improvement in hygiene management personally. The sampling was repeated after 1 year to detect possible changes in hygiene management. The highest bacterial loads (TVC, TCC, and E. coli) were observed in feeding equipment, especially the inner teat of milk feeding buckets. Environmental samples, primarily the sidewalls and back walls of tested pens and hutches, exhibited the lowest bacterial counts and ATP and protein residues. All samples were negative for MRSA and Salmonella spp. In 10.5% of all samples, ESBL was detected, and in 6.8%, ESBL E. coli was detected, predominately in sock samples, followed by feeding equipment samples. Training in hygiene management showed only limited effects. In conclusion, there is still great potential to improve the implementation of hygiene measures in individual calf housing. In particular, more attention should be paid to the cleaning of feeding buckets and artificial teats, as this is a simple means of interrupting the possible spread of pathogens among calves.     

Use of antimicrobial drugs in Swedish dairy calves and replacement heifers

A total of 3081 heifer calves in 122 Swedish dairy herds were monitored from birth to first calving, and all their diseases and treatments were recorded. There were 1268 cases of infectious diseases, of which 335 (26.4 per cent) were treated with antimicrobial drugs. Just over 90 per cent of the treatments were given during the first 210 days of the calves' lives, but only 61.8 per cent of the total quantity of antimicrobial drugs was consumed during this period. The most common diseases from birth until 210 days were respiratory diseases and diarrhoea; treatments for mastitis and interdigital phlegmon (foul in the foot) were more common after 420 days of age. Slightly more than 60 per cent of the treatments were given by the farmers without prior consultation with a veterinary surgeon.     

Pulmonary hypertension in a group of dairy calves

An episode of pulmonary arteritis and sclerosis in twenty 5- to 6-month-old dairy calves was investigated. Sixteen of the calves died acutely, without marked premonitory signs of disease. Four calves evaluated clinically had lethargy, pallor, weakness, tachycardia, tachypnea, and jugular venous distention. Cardiac catheterization performed in 3 of the calves revealed pulmonary hypertension; 1 of these calves survived. Necropsy findings in 19 calves included pale lungs and excess free fluid in the pleural and abdominal cavities. In addition, 13 of 19 calves had a dilated and thin-walled right ventricle; 4 of the calves had right-sided cardiac hypertrophy, and 2 had dilatation of the pulmonary artery. Microscopically, pulmonary arteritis and sclerosis of the small to medium-sized arteries were evident in all calves submitted for necropsy. A lung biopsy specimen from a surviving calf had similar lesions. Centrilobular hepatic necrosis was found in 17 of 19 calves. Investigation of the disease episode, including feed analysis for toxins and serologic and microbiological studies of clinically affected calves and clinically normal in-contact penmates, failed to reveal any associated risk factor. The pulmonary arterial changes in the calves were similar to lung lesions in rats fed monocrotaline.     

The effect of unrestricted milk feeding on the growth and health of Jersey calves

This study was conducted to determine the effect of feeding high milk volumes on the growth rate, health and cross-sucking behaviour in group-fed Jersey calves. Three-day-old heifers (n = 120) in a seasonal calving dairy herd were randomly assigned to one of 6 treatment groups. Three groups received high milk volumes (HMV), consisting of ad libitum milk or milk replacer feeding twice a day, while 3 groups received restricted milk volumes (RMV), consisting of 2 l twice daily, during the pre-weaning period. After a pre-weaning period during which feeding was reduced to once daily, all calves were weaned at 42 days and monitored until 60 days of age. Adjusting for birth mass, birth date, dam parity and sire, average daily mass gain (ADG), both pre-weaning (days 0-42) and overall (days 0-60), was higher in HMV than in RMV calves (P < 0.001). After weaning, growth rates showed no differences and at 60 days of age the HMV calves maintained a 6.74 kg advantage in mean body mass (P < 0.001). The mean intake of dry starter feed was higher in RMV than in HMV calves. Overall feed conversion rate of HMV calves was 9.6 % better than RMV calves. However, the variable cost per kg mass gain was 12 % higher for HMV calves. In the RMV groups 75 % of calves showed cross-sucking behaviour pre-weaning and 18 % post-weaning, whereas in HMV calves the proportions were 2 % and 7 %, respectively. There was no significant effect of milk volume on the incidence of diarrhoea. We conclude that the feeding of high volumes of milk to Jersey calves has a positive effect on growth rate, without compromising health or reducing solid feed intake after weaning. However, the higher cost of such a feeding system may limit its implementation.     

Natural transplacental infection of dairy calves with bovine immunodeficiency virus and estimation of effect on neonatal health

Many experimental infection studies with bovine immunodeficiency virus (BIV) have been conducted, but neither virus transmission under natural conditions nor longitudinal clinical effects of naturally occurring infections in non-experimental populations are well explored. We tested the hypotheses that BIV is transmitted across the placenta during gestation and that intragestionally infected calves are at increased risk of neonatal disease. A cohort of 59 dairy cows on one farm were enrolled at parturition and the BIV serostatus of the cows and their pre-colostral calves determined with an indirect fluorescent-antibody assay. Moreover, the enrolled calves were monitored thrice weekly for specific clinical signs through the duration of the 30 day neonatal period and the occurrence of clinical signs analyzed for association with calf pre-colostral BIV serostatus and dam BIV serostatus. Confounding due to calf passive immunity and season of birth were also explored. Forty percent of seropositive cows (14/35) gave birth to seropositive calves but no seropositive calves (0/19) were born to seronegative dams (estimated relative risk 16, 95% exact confidence interval 2.6–5.8×10²⁹). Calf pre-colostral BIV serostatus was not associated with the occurrence or frequency of clinical signs — but dam BIV serostatus was associated with the odds of occurrence of calf hyperthermia and with the frequency of occurrence of calf hyperthermia and hyperventilatory events. This study is inconclusive about the effects of prenatal BIV infection on neonatal health — but it does provide evidence for the natural occurrence of transplacental BIV infection.     

Effects of supplementation level and particle size of alfalfa hay on growth characteristics and rumen development in dairy calves

The aim of this study was to assess the effects of particle size (PS) of alfalfa hay on growth characteristics and rumen development in dairy calves at two levels of alfalfa supplementation. Fifty newborn dairy calves (42.7 ± 2.2 kg BW) were used in a 2 × 2 factorial arrangement with the factors supplementation level (low, 8%; or high, 16% on DM basis) and PS (medium, 2.92 mm; or long, 5.04 mm as geometrical means) of alfalfa hay. In addition, a control group without alfalfa hay was used. Hence, treatments were: control (C); low level with medium PS (LM); low level with long PS (LL); high level with medium PS (HM) or high level with long PS (HL). Growth performance of alfalfa‐fed calves did not differ from control calves, but alfalfa supplementation decreased corneum thickness of the rumen wall. In alfalfa‐fed calves, post‐weaning starter intake was greater for LL calves than for LM calves. During the entire rearing period, starter intake was 26–32% higher for LL and HM calves than for LM calves. Pre‐weaning average daily gain was higher for LL and HM calves than for HL calves, but this effect was not persistent over the entire rearing period. Final body weight decreased from 86 to 79 kg when the level of long PS alfalfa hay increased from 8 to 16%, but increased from 78 to 87 kg when the level of medium PS alfalfa increased from 8 to 16%. Regardless of PS and level, morphometric characteristics of rumen wall were generally similar among alfalfa feeding groups, but corneum thickness decreased from 8.7 to 6.1 μm with greater PS at the low level. These results indicate that adequate, but not excessive, physical stimulation is required for appropriate rumen development and growth performance of dairy calves.     

Housing, feeding and management of calves and replacement heifers in Swedish dairy herds

A questionnaire was sent to 1500 randomly selected dairy herds in Sweden, asking for general information about the herds, including routines from birth to first calving and also routines at breeding, calving and during the grazing period. Fifty-eight percent of the questionnaires were returned. The preweaned calves were kept in individual calf pens in 68% and in group housing systems in 28% of the herds. Pens with slatted floors were the main housing system for replacement heifers from weaning to breeding, and tie stalls from breeding to first calving. Whole milk was used in 44% and milk replacements in 42% of the herds. The calves received, as a median, 2.5 litres of milk per meal and 2 meals per day. The median age at weaning was 8 weeks. Age was the single most common criteria used for deciding both weaning and breeding time. The median age when the heifers were first turned out to pasture was 6 months. Prophylactic anthelmintic treatment was used by 65% of the herds. The most common diet for replacement heifers before calving was a combination of grain, hay and silage.     

The effect of intra-ruminal selenium pellets on growth rate, lactation and reproductive efficiency in dairy cattle

In each of two dairy herds (A and B), rising yearling heifers (Trial 1) and adult cows (Trial 2) were assigned to three treatment groups. Untreated animals were compared to animals treated with either two or four intra-ruminal pellets containing 3 g of elemental selenium. The administration of pellets at the recommended dose (two pellets per animal) was effective in elevating whole blood glutathione peroxidase activity and selenium concentration to over 10 times those of control animals. In Trial 1, a 15% response in liveweight gain (p<0.001) occurred in yearling heifers in the herd with the lowest pre-treatment selenium status. In Trial 2, cows receiving two pellets produced a greater milk volume (p=0.06) and more milk solids (p=0.02) than untreated controls; an increase in volume of 5.4% and 8%, and in milk solids of 6.5% and 6.4%, were noted in herds A and B respectively. There was a trend towards decreasing somatic cell counts in milk from the treated cows when compared to controls, the four-pellet group in Herd A and the two-pellet group in Herd B being significantly different from their respective control group. No between-group differences were noted in calving-first service or calving-conception intervals, nor in the proportion of animals pregnant to first or all services. The administration of selenium at twice the recommended dose rate yielded no additional response above that noted after the administration of the recommended dose. The results of this study support the use of currently recommended Ministry of Agriculture and Fisheries selenium reference ranges in cattle for the prediction of a response to supplementation.     

The effect of intra-ruminal selenium pellets on growth rate,lactation and reproductive efficiency in dairy cattle

In each of two dairy herds (A and B), rising yearling heifers (Trial 1) and adult cows (Trial 2) were assigned to three treatment groups. Untreated animals were compared to animals treated with either two or four intra-ruminal pellets containing 3 g of elemental selenium. The administration of pellets at the recommended dose (two pellets per animal) was effective in elevating whole blood glutathione peroxidase activity and selenium concentration to over 10 times those of control animals.

In Trial 1, a 15% response in liveweight gain (p<0.001) occurred in yearling heifers in the herd with the lowest pre-treatment selenium status. In Trial 2, cows receiving two pellets produced a greater milk volume (p=0.06) and more milk solids (p=0.02) than untreated controls; an increase in volume of 5.4% and 8%, and in milk solids of 6.5% and 6.4%) were noted in herds A and B respectively. There was a trend toyards decreasing somatic cell counts in milk from the treated cows when compared to controls, the four-pellet group in Herd A and the two-pellet group in Herd B being significantly different from their respective control group. No between-group differences were noted in calving-first service or calving-conception intervals, nor in the proportion of animals pregnant to first or all services. The administration of selenium at twice the recommended dose rate yielded no additional response above that noted after the administration of the recommended dose. The results of this study support the use of currently recommended Ministry of Agriculture and Fisheries selenium reference ranges in cattle for the prediction of a response to supplementation.     

A preliminary experiment on the effect of selenium on the growth rate of calves

Abstract

Extract

Drake et al. (1960 Drake, C, Grant, A. B. and Hartley, W. J. 1960. N.Z. vet. J., 8: 7–7. [Taylor &; Francis Online] , [Google Scholar]) have shown that selenium will control outbreaks of lamb and hogget ill-thrift on the pumice soils of the Rotorua-Taupo area. As an ill-thrift problem also exists in calves on the newly-broken-in farms in the same area, it was decided to investigate the effect of oral selenium and other minerals in the control of this problem.     

Effect of group size and structure on the welfare and performance of pregnant sows in pens with electronic sow feeders

Pregnant sows were housed in dynamic, twice-mixed, and static groups of different sizes in pens with electronic sow feeders (ESFs) to study the effect of group size and structure on sow welfare and performance. The total injury score (TIS) was significantly higher (P < 0.05) in the dynamic group than in the other groups in general and 2 wk after mixing. The salivary cortisol concentrations were similar in the 3 groups. The frequency of queuing was significantly higher (P < 0.05) in the twice-mixed group and the frequency of nonagonistic social interactions significantly lower (P < 0.05) in the dynamic group. The total number of aggressive acts was positively and significantly correlated (P < 0.05) with the frequency and duration of queuing in all the groups. Farrowing performance and longevity did not differ between the groups. The higher TIS and lower number of nonagonistic social interactions indicated that welfare was compromised in the dynamic group as compared with the other groups.     

Feed intake and oral behaviour of dairy calves housed individually or in groups in warm or cold buildings

The influence of environmental temperature, housing, social company and age on the feed intake and oral behaviours was studied by housing male dairy calves for seven weeks individually (INDIV) or 12 weeks in groups of four; indoors (INGROUP) or outdoors either with (OUTWARM) or without a heated shelter (OUTCOLD). During the milk-feeding period (1–7 experimental weeks), the mean daily milk, hay and total dry matter intakes of INDIV calves were lower than of INGROUP calves (P < 0.05). No differences in the feed intake between OUTWARM, OUTCOLD or INGROUP were found. Nor was found any differences in the feed efficiency (growth kg^− 1 DM) between the treatments. After weaning off milk, during experimental weeks 8 to 11, the total dry matter intake of INGROUP tended to be greater than that of OUTWARM (P = 0.05). There were no other differences in the mean daily feed intakes, nor in the feed efficiency. During the milk-feeding period, INGROUP calves ate more often concentrates (P = 0.05) and ruminated more (P = 0.01) than INDIV calves. During the 12-week experiment, INGROUP calves licked themselves more often than OUTCOLD calves (P = 0.04) and tended to lick more often than OUTWARM calves (P = 0.08). INGROUP calves licked more often penmates or structures and bit more often structures than OUTWARM or OUTCOLD calves (P < 0.05 for all). Overall, with a decreasing temperature, the calves in outside groups spent less time performing oral behaviours. We conclude that group rearing may facilitate calves to start eating and ruminating earlier than individual housing. The effect of low temperatures on the time spent eating solid foods is discussed in relation to housing design.     

The effect of veterinary-treated clinical mastitis and pregnancy status on culling in Swedish dairy cows

The interaction of the effects of pregnancy status and veterinary-treated clinical mastitis on culling in Swedish dairy cattle was analyzed with survival analysis. The data were from 978,780 cows with first calvings between 1988 and 1996. Four breeds (Swedish Red and White (SRB), Swedish Friesian (SLB), Swedish Polled Breed and Jersey) were included in the analysis, together with the SRB x SLB crossbreds. Length of productive life was defined as the number of days between first calving and culling or censoring (end of data collection). The model (Weibull proportional hazard) included the interaction of parity by pregnancy status by veterinary-treated clinical mastitis, peak test-day milk-yield deviation within herd-year-parity, age at first calving, year by season, region, breed, herd production level, and the random effect of herd. The effects of pregnancy status and veterinary-treated clinical mastitis were modeled as time-dependent covariates. The lactation was divided into five stages during which a veterinary-treated clinical mastitis and culling might occur and in which the pregnancy status was assumed to be known and culling could occur. Open cows had a pronounced effect on culling: they had a very high risk of being culled in all lactations, and it was even higher if they were treated for mastitis in early lactation. For pregnant cows, the later they got pregnant during the lactation, the greater their risk to be culled. The risk associated with cases of veterinary-treated clinical mastitis remained important throughout the lactation.     

Effects of a prebiotic supplement on health of neonatal dairy calves

Calf morbidity and mortality represent major financial losses for many dairy producers. The primary cause of calf mortality in the U.S. is diarrhea caused by intestinal bacterial infections. Traditionally, formulated antibiotics in milk replacer have been used as preventive treatments. However, as consumer concern about antibiotic resistance has increased, interest in alternative supplements has grown. Prebiotics, which are food ingredients not digestible by animal enzymes, and probiotics, which are beneficial bacteria, are two proposed alternatives for antibiotics to reduce diarrhea and improve immunity in calves. In this trial 75 Holstein heifer calves were randomly assigned to one of 3 treatments: control (C; no additive), antibiotic treatment (A; oxytetracycline 0.220 g/kg and neomycin base 0.441 g/kg), and prebiotic supplement (PB; 20 g/day Prebio Support™, Meiji Feed Co., Ltd. Tokyo, Japan). Calf scours, respiratory, and general appearance scores were not affected by treatment. No statistical differences were detected in any of the health data collected; however, treatment C had nearly twice as many calves that scoured and refused feed than treatments A and PB. Populations of beneficial and pathogenic bacteria in feces were generally not affected by treatments. However, PB treatment calves had an overall trend for more Lactobacilli in their feces than calves fed A (P = 0.08), and Enterobacter population was greater in C calves than in calves on treatment A in week 4 (P < 0.05). There was a tendency for the PB treatment to have elevated populations of beneficial species of bacteria during week 2. Populations of lymphocytes carrying CD4 and CD8 markers were not affected by treatment. Fecal IgA concentration decreased as calf age increased, with the greatest concentration in week 2 (P < 0.01) for all calves. Fecal IgA levels were numerically greater for the PB group in weeks 2 and 4. Both PB and A treatments affected fecal parameters with PB having positive effects in several areas. Since calves in this study were generally healthy, observable benefits from the treatments were likely minimized.