Interactions between cattle and badgers at pasture with reference to bovine tuberculosis transmission

The normal behaviour of badgers, as described here, would not result in direct transmission of tuberculosis from badgers to cattle via air expired by badgers or via bodily contact. All activities of wild badgers in cattle fields at three different sites were observed at night for a total of 359 h. In addition, all activities of pairs of wild caught badgers were observed in a 0.5 ha enclosure with an artificial sett on 20 nights when cattle were present. Badger foraging in cattle fields was infrequent during dry conditions and variable at other times. Clover fields were preferred to grass pastures in two autumnal studies and under dry conditions the badgers did not prefer to forage on short pasture. Badgers consistently avoided close contact with cattle by changing routes from sett to foraging site and by foraging much less in areas of fields occupied by cattle. When foraging they preferred to remain at least 10-15 m from cattle and they avoided compact groups of cattle more than individuals. Some cattle would move towards badgers, especially if they were carrying out unusual behaviour, but badgers fled rapidly from every approach. In all potential encounters badgers were able to keep at least 2-3 m from approaching cattle. Badgers in the artificial sett delayed entering the enclosure if cattle were within 15 m of the entrance. When cattle were managed on a strip-grazing (rotational) system the whole area which they occupied was avoided by the badgers. However, badgers came closer to individual cattle and foraged in areas grazed by the cattle more if the cattle were set-stocked. If cattle are managed so that they are concentrated in a small area (rotational) system the risk of disease transmission is minimized because they are less likely to encounter badgers or their fresh products than are cattle managed on a large area (set-stocked) system.     

牛型提纯结核菌素变态反应检测奶牛结核病的试验

结核病是一种人畜共患的慢性传染病,而奶牛结核病的流行,不但影响奶牛养殖业的发展,而且由于交叉感染而使人类的健康受到威胁。本病表现为病程长,症状逐步加重,生产性能不断下降。奶牛结核病最常见为肺结核,其次为淋巴结核、乳房结核、肠结核。在临床上可见渐进性消瘦,长期不愈的咳嗽,慢性乳房炎,体表淋巴结肿大、化脓,顽固性下痢等症状。     

Disease frequencies of tied zero-grazing dairy cows and of dairy cows on pasture during summer and tied during winter

Disease frequencies of Swedish Red and White Breed (SRB) and Swedish Friesian Breed (SLB) in tied herds with zero-grazing management system and in tied herds with pasture periods are presented. Incidences are compared both with respect to season and between the two systems. Figures are given for accidents and nine different diseases.In zero-grazing cows no seasonal difference could be demonstrated except for a higher risk of ketosis and tramped teat during wintertime for SRB.Cows of both breeds kept on pasture had lower risks of dystocia, ketosis, mastitis and tramped test during this period, but an increased risk of accidents and inflammation of the hoof(s). SRB cows also had higher risks of retained placenta, parturient paresis and non-inflammatory diseases of the hoof(s) during pasture period.Comparison of year-round incidence in the two management systems revealed a higher risk of retained placenta in zero-grazing cows of both breeds and higher risk or parturient paresis in zero-grazing SRB cows. The risk of accidents was decreased in zero-grazing cows of both breeds.The relative risks of tramped teat, mastitis and diseases of the hoof(s) varied depending on the herd size distribution of the control group. Increased risk of mastitis in zero-grazing cows of both breeds and of tramped teat in zero-grazing SLB cows was found when comparing with cows from a group of mainly smaller herds with pasture feeding during summer. However, comparison with cows from a group of herds with the same herd size distribution as zero-grazing cows revealed decreased risk of tramped teat, mastitis and inflammation of the hoof(s) in zero-grazing SRB cows and decreased risk of diseases of the hoof(s) in zero-grazing SLB cows.     

Some effects of feeding pasture silage as a supplement to pasture on reproductive performance in lactating dairy cows

Supplementation of a ryegrass/white clover pasture diet with pasture silage is a common management practice in New Zealand dairy herds. The effect of this supplementation on reproductive performance has not been investigated. Five herds of 20 cows were formed before calving commenced on 1 June 1992. From 5 August to 4 September, two of these herds were fed 5 kg/cow/day of pasture silage in addition to the ryegrass/white clover pasture offered to all herds. Pasture silage supplementation did not alter the intervals from calving to first ovulation, first oestrus, or to conception. However, it reduced the first service conception rate (37.5% v. 53.3%; difference +/- sed = 15.8 +/- 10.0%, for pasture and silage and pasture only cows, respectively). A positive effect on reproductive performance of pasture silage supplementation was not demonstrated in this trial.     

Hematological profiles in dairy cows treated with recombinant bovine somatotropin.

Recombinant bovine somatotropin (bST) was administered at 0, 10.3, or 20.6 mg per cow per day to 32 Holsteins for 38 wk. Fifteen currently treated cows had been treated in the previous lactation. Eighteen hematological variables and blood concentration of insulin-like growth factor I (IGF-I) were measured at five sample periods. The objectives of the study were to test the effects of bST treatments on hematological profiles and to relate blood IGF-I concentration to these variables. Results indicated little influence (P greater than .10) of previous bST treatments on hematological profiles measured in the current lactation. Current bST treatments, however, altered hematocrits (P = .10), mean corpuscular volume (P = .03), mean corpuscular hemoglobin (P = .009), and fraction of blood lymphocytes (P = .09). A week x bST treatment interaction also contributed to variation in hematocrit (P = .09), mean corpuscular hemoglobin (P = .05), fraction of neutrophils (P = .02), and fraction of lymphocytes (P = .04). Blood IGF-I concentration influenced fractions and counts of neutrophils (P = .06, .09), lymphocytes (P = .04, .02), and monocytes (P = .08, .05). Further in vivo and in vitro studies are warranted because this preliminary evidence suggests that bST and(or) IGF-I contribute to regulation of hematopoiesis in mature dairy cows.     

Simulation model of within-herd transmission of bovine tuberculosis in Argentine dairy herds

Transmission of bovine tuberculosis was quantified in three dairy herds located in south Santa Fe Province, Argentina. Using estimates of Mycobacterium bovis transmission (β) and a Reed–Frost simulation model, the prevalence of tuberculosis infection in the study herds over time was investigated. The Reed–Frost model was modified by incorporating randomness in both β and the incubation period () of M. bovis. The mean estimated herd β was 2.2 infective contacts per year and did not differ significantly between the study herds. Modeling as Poisson distributed (mean 24 months) best fit the observed prevalences. Infection was predicted by the model either to spread quickly (<10 years) within a herd and reach a high prevalence (>50%), or to persist at a low prevalence (<5–10%). The model was robust, predictions were realistic and the mean β estimated was consistent with previous studies of bovine tuberculosis.     

Rumination behavior of grazing dairy cows in response to restricted time at pasture

The short-term adaptations of cattle behavior to time restrictions at pasture are poorly understood. This study explored the diurnal rumination pattern of dairy cows in response to restrictions to time at pasture. Six groups of eight Holstein–Friesian cows (470 ± 47 kg, 35 ± 9 days in milk) were strip-grazed on a perennial ryegrass (Lolium perenne L.) pasture over 21 days (2 groups per treatment) for either 4 h after each milking (2 × 4), one period of 8 h between milkings (1 × 8), or 24 h excluding milking times (control, CTL). All cows were equipped with HR Tag™ rumination collars which recorded chewing activity and regurgitation of digesta boluses during rumination. Cows in 1 × 8 reduced daily rumination time by 36% compared with cows in 2 × 4 and CTL (304, 402 and 423 SED 26.3 min, respectively). There were no differences in the average intervals between regurgitation of digesta boluses (48.9 ± 0.96 s) and average interval between chewing actions was also similar (0.7 ± 0.02 s) between treatments. Treatment affected the diurnal rumination pattern. There was little rumination during the time at pasture for the restricted cows (1 × 8 and 2 × 4), whereas the CTL cows ruminated for almost a third of the time between the am and pm milking. In all treatments, cows ruminated the longest during the night. These results suggest grazing dairy cows modulate their time for rumination to compensate for a reduction in available grazing time. This behavioral study contributes to the understanding of changes in rumination behavior and associated effects in grazing dairy cattle in response to hunger.     

Lack of evidence of transmission of bovine leukemia virus by rectal palpation of dairy cows

A study was undertaken in a California dairy to estimate the risk of transmission of bovine leukemia virus associated with rectal palpation of cows. The probability of seroconversion within 3 months after rectal palpation was examined as a function of the prevalence of infection in cows at the time of palpation. It was hypothesized that the probability of seroconversion within 3 months after palpation would be higher for cows in a group with high prevalence of infection than for cows in a group with low prevalence. The probability of seroconversion after rectal palpation was equal to 0.034, and results of logistic regression, using data from 1,116 noninfected and 1,047 infected cows, did not indicate any significant association between probability of seroconversion after rectal palpation and prevalence of infection (P = 0.189). Results of this study suggest that risk of bovine leukemia virus transmission by rectal palpation typically used in reproductive tract examination of cows either does not occur or is uncommon.     

The grazing response of cattle to pasture contaminated with rabbit faeces and the implications for the transmission of paratuberculosis

Transmission of Mycobacterium avium subspecies paratuberculosis, the organism responsible for paratuberculosis (or Johne's disease) in ruminants, occurs through the faecal-oral route. As M. a. paratuberculosis has been isolated from rabbit faeces, cattle grazing rabbit faecal contaminated pasture may thus be at risk.A herd of 57 beef cattle was monitored on a farm in Perthshire, throughout the 1999 'grazing year', to investigate whether the cattle avoided rabbit faecal contaminated pasture and thus the potential for disease transmission. Grazing was measured every two days over eight rotations by sward heights on 40 marked treatment plots (0.5 m x 0.5 m) to which 0, 10, 50 and 250 rabbit faecal pellets were added. Cattle were also monitored by an active transponder system which enabled individual animals contacting two plots per field rotation (one control and one contaminated) to be recorded. During the monitored grazing year, grazing pressure was low with a net mean sward offtake of 18% of sward height per rotation. There were no significant differences between rabbit faecal treatments (0, 10, 50 and 250 pellets) with respect to the height or proportion of sward removed, or between the numbers of contacts made by cattle on contaminated and uncontaminated plots. Over 90% of all the cattle contacted contaminated plots, indicating that the potential for disease transmission was widespread among the herd.To our knowledge, this is the first reported instance of a lack of avoidance by grazing cattle towards swards contaminated with faeces, and implies that the potential for transmission of paratuberculosis from rabbit contaminated pasture is high.     

Prevalence of parasite eggs and cysts in faeces from dairy cows in Colombia

Summary When 1, 711 bovine faecal samples from 113 farms in eight dairy areas of Colombia were examined for the presence of helminth eggsFasciola hepatica eggs were found in the faeces from 60% of the farms and samples from animals kept above 2,000 m. Strongyle eggs were found in faeces from 82% of the farms and in 18% of the samples.

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Resumen Se examinaron 1.711 muestras fecales provenientes de 113 fincas, localizadas en ocho zonas lecheras de Colombia. Se encontraron huevos deFasciola hapatica, en el 60% de fincas y muestras fecales de animales sobre los 2,000 m.s.n.m. Se encontraron tambien huevos de estrogilideos en heces del 82% de fincas y en el 18% de las muestras examinadas.

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Résumé La recherche d’oeufs d’helminthes sur 1711 échantillons de fécès provenant de 113 fermes de 8 districts laitiers de Colombie a permis de noter la présence d’oeufs deFasciola hepatica dans 60 p. 100 des fermes et échantillons originaires d’animaux vivant à plus de 2,000 m. Des oeufs de strongles ont été notés dans les fécès provenant de 82 p. 100 des fermes et 18 p. 100 des échantillons.

     

Response to metabolic challenges in early lactation dairy cows during treatment with bovine somatotropin

Milk production is increased in lactating cows treated with bovine somatotropin (bST) because a greater portion of absorbed nutrients are partitioned for milk synthesis. This homeorhetic action may be caused by alterations in response of key tissues to homeostatic signals. To examine this theory, acute metabolic challenges were administered to 8 multiparous Holstein cows (61 +/- 2 days postpartum) receiving daily subcutaneous injections of pituitary-derived bST (26.3 mg) or excipient during two 14-day treatment periods (crossover experimental design). Treatment with bST increased milk yield 12%. Feed intake did not change so that net energy balance decreased (+ .5 vs. -4.3 Mcal/day). Plasma concentrations of nonesterified fatty acids (NEFA) were chronically elevated in bST-treated cows, consistent with energy balance differences. However, baseline concentrations of glucose, insulin, and glucagon in plasma did not differ. On the last 3 days of treatment, individual metabolic challenges were administered via jugular cannulas: epinephrine (700 ng/kg BW), glucose (250 mg/kg BW), insulin (1.0 micrograms/kg BW), and glucagon (175 ng/kg BW). Plasma glucose was reduced after the insulin challenge to a lesser extent during bST treatment. In bST-treated cows, the increase in plasma NEFA in response to epinephrine was greater, and NEFA concentrations were lowered to a greater extent after insulin and glucose challenges. Glucose, insulin, and glucagon removal rates were not altered, nor was plasma glucose response to epinephrine or glucagon challenges. Treatment of lactating cows with bST primarily altered the response of adipose tissue to homeostatic signals which affect lipid metabolism.     

Vertical transmission of bovine leukemia virus and bovine immunodeficiency virus in dairy cattle herds.

Vertical transmission of bovine leukemia virus (BLV) and bovine immunodeficiency virus (BIV) was investigated in five dairy cattle herds in Hokkaido, where 36.1 and 17.0% of cattle were BLV and BIV seropositive, respectively, and 9.9% of dams were co-infected with both BIV and BLV. Twenty six cases of offspring born from dams infected with only BLV (17 cases) or with both BIV and BLV (9 cases) were examined for the presence of BLV and BIV before and after colostrum feeding by polymerase chain reaction (PCR) and syncytium assay. After birth, all calves were separated immediately from their dams. The offspring born from BLV-positive dams were BLV-negative before colostrum feeding, suggesting that no transplacental transmission had occurred. Thereafter, these offspring were fed colostrum or milk from their dams, but still remained BLV-negative. The other offspring born from BLV-positive dams were fed with BLV-negative colostrum, or with pasteurized BLV-positive colostrum. All these calves remained negative for BLV infection, suggesting that in utero transmission of BLV is negligible. In the case of offspring born from dams co-infected with BLV and BIV, calves were BIV-positive before colostrum feeding at 1 day after the birth, indicating in utero transmission of BIV. After colostrum feeding from their dams, newborn calves became BLV-positive. In addition, one calf was BLV-positive even before colostrum feeding. These results suggest that BIV can be transmitted to offspring in utero, and that BLV can be transmitted through colostrum or milk if dams are infected with both BIV and BLV.     

Changes in fatty acid composition of milk from lactating dairy cows during transition to and from pasture

Five Holstein cows producing an average of 25.4 ± 6.4 kg/d and 347 ± 111 days in milk were used to study the changes in fatty acid composition in milk from lactating dairy cows during transition to and from pasture. The 45-d experiment was divided into 3 periods. During the first 2 d of the experiment (Period I), cows were fed a TMR diet containing 50% conserved forage and 50% grain. On day 3, cows were turned out to pasture and remained on all-pasture diet for 29 d (Period II). On day 32, cows were withdrawn from pasture and offered a TMR diet until day 45 (Period III). Milk yield was recorded daily, and milk fat content and fatty acid (FA) composition were determined daily for composite samples collected from a.m. and p.m. milkings. Data were analyzed using spline regression (H₀ = zero slope) to determine whether there was any change in the concentration of a particular fatty acid after a specific time or whether it had stabilized. Cows produced an average of 25.2 ± 5.5, 13.7 ± 5.6, and 12.1 ± 4.8 kg/d of milk with 3.6, 4.2, and 3.6% fat during pre-pasture, pasture, and post-pasture diets, respectively. The conjugated linoleic acid (CLA) content was 0.45% of total fat during pre-pasture, reached to a maximum of 2.53% on day 23 into pasture and plateaued thereafter for the period. Milk fat C_18:1 t-11 content was 2.89% of total fat during pre-pasture, reached a maximum of 7.95% after day 22 in pasture, and plateaued afterwards. The C_18:2 content declined gradually from pre-pasture to pasture diet with no further decrease observed after day 22, while C_18:3 content increased until day 7 on pasture. The post-pasture CLA content in milk fat reached a value similar to pre-pasture within 4 days after the cows were withdrawn from pasture. No change in other fatty acids was observed after day 7 once the cows were switched to post-pasture diet. In the present study, it took 23 days to establish the highest level of CLA in milk fat after turning cows out to pasture, whereas only 4 days were needed to bring it back to the original level once the cows were withdrawn from pasture. Other milk fatty acids were stabilized around day 23 after turning cows out to pasture and by day 7 after being withdrawn from pasture and put back on a TMR diet inside the barn.     

Influence of floor surface and access to pasture on claw health in dairy cows kept in cubicle housing systems

In this study, the effects on the claw health of dairy cows of three different floor types and access to pasture were investigated on 35 farms. The farms were fitted with a given floor type in the indoor walking area of a cubicle housing system: a solid rubber, mastic asphalt or slatted concrete floor. Because we chose farms on which the given floor type was in good condition, the data presented show what can be achieved on these types of floors under ideal circumstances. Cows on half of the farms per floor type had access to pasture during the grazing period. Each farm was visited three times at approx. 6-month intervals at the end of the winter indoor-housing period and at the end of the summer period, i.e. after the period with access to pasture on half of the farms. During each visit, the claw health of the same 10 cows per farm was assessed on the occasion of routine claw trimming. The proportion of cows with haemorrhages increased from mastic asphalt to rubber and slatted concrete floors. A lower proportion of cows kept on mastic asphalt was affected by white-line fissures and needed intermittent claw-trimming, an indicator for lameness. Cows housed in cubicle systems with slatted concrete floors were at the lowest risk of having heel-horn erosions. Access to pasture was associated with a lower incidence of slight white-line fissures and dermatitis digitalis. A higher proportion of cows with sole haemorrhages and sole ulcers were found on all floor types at the end of the summer period than at the end of the winter indoor-housing period. Floor type did not influence the presence of sole ulcers and deep white-line fissures. In conclusion, the effect of floor type on claw health was slight, and none of the investigated floor types was clearly superior to the others. Access to pasture was not effective in reducing the presence of most types of claw lesions associated with the floor type used in the indoor walking area.     

Rectal palpation and transmission of bovine leukemia virus in dairy cattle.

To determine whether rectal palpation, using common obstetrical sleeves, serves as a mode of transmission of bovine leukemia virus in dairy cattle, field studies were conducted at 2 dairies. At a commercial dairy, significant difference was not observed in rate of seroconversion in heifers and cows in which the same sleeve or new sleeves were used for palpations. At a university dairy, where cattle were used to teach dairy husbandry and veterinary procedures, significantly (P less than 0.02) greater rate of seroconversion was observed in heifers and cows palpated with unwashed common sleeves than that observed in heifers and cows palpated with sleeves washed between use. Although rectal transmission of bovine leukemia virus under field conditions was documented, it was related to frequency of palpation and age of cattle.     

Comparison of three techniques for estimating the forage intake of lactating dairy cows on pasture

Quantifying DMI is necessary for estimation of nutrient consumption by ruminants, but it is inherently difficult on grazed pastures and even more so when supplements are fed. Our objectives were to compare three methods of estimating forage DMI (inference from animal performance, evaluation from fecal output using a pulse-dose marker, and estimation from herbage disappearance methods) and to identify the most useful approach or combination of approaches for estimating pasture intake by lactating dairy cows. During three continuous 28-d periods in the winter season, Holstein cows (Bos taurus; n = 32) grazed a cool-season grass or a cool-season grass-clover mixture at two stocking rates (SR; 5 vs. 2.5 cows/ha) and were fed two rates of concentrate supplementation (CS; 1 kg of concentrate [as-fed] per 2.5 or 3.5 kg of milk produced). Animal response data used in computations for the animal performance method were obtained from the latter 14 d of each period. For the pulse-dose marker method, chromium-mordanted fiber was used. Pasture sampling to determine herbage disappearance was done weekly throughout the study. Forage DMI estimated by the animal performance method was different among periods (P < 0.001; 6.5, 6.4, and 9.6 kg/d for Periods 1, 2, and 3, respectively), between SR (P < 0.001; 8.7 [low SR] vs. 6.3 kg/d [high SR]) and between CS (P < 0.01; 8.4 [low CS] vs. 6.6 kg/d [high CS]). The period and SR effect seemed to be related to forage mass. The pulse-dose marker method generally provided greater estimates of forage DMI (as much as 11.0 kg/d more than the animal performance method) and was not correlated with the other methods. Estimates of forage DMI by the herbage disappearance method were correlated with the animal performance method. The difference between estimates from these two methods, ranging from -4.7 to 5.4 kg/d, were much lower than their difference from pulse-dose marker estimates. The results of this study suggest that, when appropriate for the research objectives, the animal performance or herbage disappearance methods may be useful and less costly alternatives to using the pulse-dose method.