Paratuberculosis sero-status and milk production,SCC and calving interval in Irish dairy herds

The objective of this study was to investigate the impact of paratuberculosis sero-status on milk yield, fat, protein, somatic cell count and calving interval in Irish dairy herds. Serum from all animals over 12 months of age (n = 2,602) in 34 dairy herds was tested for antibodies to Mycobacterium avium subsp. paratuberculosis using an ELISA. Herds were categorised by sero-status into positive, non-negative and negative, where a positive herd contained two or more positive cows, a non-negative herd contained only one positive cow and a negative herd contained no positive cows. Data at animal, parity and herd-level were analysed by multiple regression using general linear models. Positive herds (mean herd size = 129 cows) and non-negative herds (81 cows) were larger than negative herds (72 cows) (P < 0.01). Negative herds had the highest economic breeding index (EBI), while positive herds had the highest estimated breeding value (EBV) for milk yield. There was no significant effect of paratuberculosis sero-status at animal, parity or herd-level on milk yield, milk fat or protein production, somatic cell count score (SCCS) or calving interval. Negative herds tended to have a lower SCCS than positive and nonnegative herds (P = 0.087). This study only examined the effects of paratuberculosis sero-status but did not examine the clinical effects of Johne's disease at the farm or dairy industry levels.     

A study of dry cow therapy and effects on SCC in 10 Irish dairy herds

Somatic cell count (SCC) data for 480 cows in 10 Irish dairy herds from January 2001 until June 2002 were analysed. Herds were selected on the basis of a recent or ongoing history of clinical or subclinical mastitis. An individual cow SCC of 200 000 cells per ml was used as the threshold for elevation of SCC. The duration of elevated SCC prior to drying-off and the magnitude of the elevation in SCC were found to have an impact on the response to dry cow therapy (DCT). A trend also emerged indicating that increasing parity had a negative influence on the response to DCT.     

Effects of calving age, breed fraction and month of calving on calving interval and survival across parities in Irish spring-calving dairy cows

The objective of this study was to investigate the effect of parity, age at calving, percentage North American Holstein-Friesian and calving date on subsequent calving interval and survival to facilitate the estimation of transition probabilities for month of calving. The economic value of traits that influence calving date, age distribution and survival can be assessed in models using a transition probability matrix. Such a matrix contains the probabilities that a cow of a particular age or breed calving in a particular month will calve in the same, an earlier or later month next year, or be culled. Following editing 1,046,855 calving records in spring-calving herds between the years 1990 and 2004 were analysed. Shorter calving intervals were associated with cows calving later in the calendar year. Age at first calving of < 24 months resulted in longer calving intervals to second calving across all levels of Holstein percentage with cows calving for the first time at 25–26 months of age having the shortest subsequent calving interval. Age at second calving of 37–38 months and third calving of 49–50 months were optimum for shorter subsequent calving intervals. Calving interval increased with Holstein percentage across the first 5 parities. Survival rate decreased with later month of calving and with older parities. When survival rate was measured as the ability of the cow to re-calve within 500 days, the highest survival rate was found in cows calving at 25–26 months of age whereas there was a noticeable reduction in survival across all parities in the 88–100% Holstein percent category.     

The effect of Lameness before and during the breeding season on fertility in 10 pasture-based Irish dairy herds

Background

The effects of lameness on fertility have been documented frequently but few data are available from seasonally breeding, pasture-based herds (such as those used in Ireland) where cows are housed during the winter months but managed at pasture for the remainder of the year. This study determined the prevalence of lameness in a group of 786 cows in 10 pasture-based Irish dairy herds before, during and after the breeding season and assessed the relationship between lameness and the reproductive performance in these herds through serial locomotion scoring during the grazing period.

Results

Lameness prevalences of 11.6 % before, 14.6 % during and 11.6 % after the breeding season were found and these compared favourably to results from housed cattle and are similar to other studies carried out in grazing herds. A Cox proportional hazards model with locomotion score as time varying covariate was used. After controlling for the effect of farm, month of calving, body condition score at calving, body condition score loss after calving and economic breeding index, cows identified as lame during the study were less likely to become pregnant. Cows lame before the earliest serve date but no longer lame during the breeding season, cows becoming lame after the earliest serve date and cows identified lame both before and after this date were respectively 12 %, 35 % and 38 % less likely to become pregnant compared to cows never observed lame during the study. However, these findings were only significant for cows becoming lame after the earliest serve date and cows lame both before and after the start of breeding.

Conclusions

This study found that the reproductive efficiency was significantly (p < 0.05) lower in cows becoming lame during the breeding season and cows lame before and during the breeding season compared to non-lame cows. Cows no longer lame during the breeding season had a lower Submission Rate to first serve within 3 weeks of earliest serve date. However, the Pregnancy Rate was not significantly (p > 0.05) lower in these animals compared to cows never diagnosed as lame. In addition to lameness status, nutritional status and genetics were found to influence the reproductive performance in pasture-based Irish dairy herds.     

Accuracy of fetal age estimates using transrectal ultrasonography for predicting calving dates in dairy cows in seasonally calving herds in New Zealand

AIM: To describe the accuracy of transrectal ultrasonography for predicting calving dates in dairy cows under typical New Zealand conditions and to assess potential risk factors for differences between predicted and actual calving dates.

METHODS: Data were collected from 116 seasonally calving herds over 2 years in a retrospective single cohort study. Transrectal ultrasonography was undertaken by experienced veterinarians (n=12) to determine if cows were pregnant, and if so to estimate fetal age. Predicted calving date was calculated by adding 282 days to the estimated conception date. Accuracy was assessed using differences between predicted and actual calving dates for each animal. Potential risk factors for animals calving >10 days before or after their predicted calving date were assessed using multinomial logistic regression models.

RESULTS: The study population comprised 83,104 cows over the 2 years of the study; 75,037 (90.3%) cows calved within 10 days of their predicted calving date, 3,683 (4.4%) calved >10 days earlier, and 4,384 (5.3%) >10 days later, than predicted. Risk factors for calving >10 days before or after the predicted calving date included having >1 artificial insemination (AI) before pregnancy diagnosis (p=0.03), where the cow’s most recent AI was <21 days before the end of the herd’s AI period (p<0.01), and where the diagnosis was made at the second or third herd-visit (p<0.01). The probability of calving being >10 days later than predicted also increased when the fetus was ≥13 weeks old at pregnancy diagnosis (p<0.01).

CONCLUSIONS AND CLINICAL RELEVANCE: In this study, >90% of cows diagnosed pregnant by veterinarians using transrectal ultrasonography calved within 10 days of the predicted calving date. In herds where herd reproductive performance is high, it would be expected that more cows would conceive to their first AI, and potentially fewer cows would have AI close to the end of the herd’s AI period, which would increase diagnostic accuracy. Where herd managers rely on accurate predicted calving dates they should be informed about realistic expected accuracy. For greatest accuracy, a complete AI history should be made available to the person performing the pregnancy diagnoses and cows at most risk of having inaccurate predicted calving dates should be identified.     

Early calving heifers versus maiden heifers for beef production from dairy herds. II. Physicochemical and sensorial characteristics of meat

The influence of early calving (20–21 months) on meat quality was studied in 158 Friesian or Charolais × Friesian crossbred heifers receiving two different feeding levels between 5 and 14 months old and slaughtered at 2 years of age. The effects of genotype and feeding level were also examined. Meat quality was assessed through physico-chemical measurements on three or seven muscles per carcass. In addition, sensory evaluation (preference test) was conducted in three muscles from selected carcasses.In once-calved heifers, meat was juicier and water holding capacity and dry matter content were lower than in maiden heifers. In Charolais × Friesian, meat colour tended to be lighter after calving, but the effect of calving on tenderness was variable.The meat of Friesians was darker in colour than that of Charolais × Friesian, with a rather better water holding capacity. The shear values of raw meat were not dependent on genotype; after cooking, these varied with respect to muscle. In panel testing, meat of Friesian maiden heifers was always judged to be more tender than that of the Charolais × Friesian. No obvious differences in juiciness and flavour were observed in maiden heifers according to genotype.The increase in feeding level between 5 and 14 months of age resulted in darker meat, and in the Charolais × Friesian animals, in a higher dry matter content of the meat; the other physicochemical characteristics as a whole were not changed.     

Use of every ten-day criteria for metabolic profile test after calving and dry off in dairy herds

The traditional metabolic profile test cannot be applied to peripartum dairy cows, because these cows are in a state of physiological abnormality making it difficult to interpret their blood components. This study aimed at establishing and evaluating the practicability of interpreting a metabolic profile test every 10 days (Ten-day criteria) during the dry and lactation periods in herds with high and no incidence of peripartum diseases. Data from 29,043 cows in 1,130 commercial dairy herds were used to establish standard values every 10 days, mean +/- 1.0 standard deviation for the metabolic profile test. The practicability of these criteria was evaluated in herds with peripartum diseases. In the ten-day criteria, the body condition score, albumin, blood urea nitrogen, glucose, total cholesterol, nonesterified fatty acids, gamma-glutamyl transpeptidase and aspartate aminotransferase, fluctuated during the dry and early lactation periods and there were very big changes in packed cell volume, blood urea nitrogen, total cholesterol and magnesium just after calving. The ten-day criteria were able to detect overconditioned cows, low levels of albumin, total cholesterol and magnesium, and high nonesterified fatty acids in herds with a high incidence of peripartum diseases. In conclusion, the ten-day criteria can be successfully applied to peripartum cows, and is recommended because it is able to detect metabolic abnormalities not only in the herd, but also in individual cows.     

Inbreeding effects on postweaning production traits, conformation, and calving performance in Irish beef cattle

The objective of this study was to quantify the effect of inbreeding on carcass quality, growth rate, live conformation measures, and calving performance in purebred populations of Charolais, Limousin, Simmental, Hereford, and Angus beef cattle using data from Irish commercial and pedigree herds. Variables analyzed are reflective of commercial farming practices. Inbreeding was included in a linear mixed model as either a class variable or a linear continuous variable. Nonlinear effects were nonsignificant across all traits. Inbred animals had decreased carcass weight and less carcass fat. The effects of inbreeding were more pronounced in the British beef breeds. Effects for carcass weight ranged from -0.87 kg (Charolais) to -1.90 kg (Hereford) per 1% increase in inbreeding. Inbred Charolais and Hereford animals were younger at slaughter by 3 and 5 d, respectively, per percentage of increase in inbreeding, whereas the effect of inbreeding on age at slaughter differed significantly with animal sex in the Limousin and Angus breeds. Inbred Limousin and Angus heifers were younger at slaughter by 5 and 7 d, respectively, per percentage of increase in inbreeding. Continental animals were more affected by inbreeding for live muscling and skeletal conformational measurements than the British breeds; inbred animals were smaller and narrower with poorer developed muscle. Calf inbreeding significantly affected perinatal mortality in Charolais, Simmental, and Hereford animals. The effects were dependent upon dam parity and calf sex; however, where significant, the association was always unfavorable. Dam inbreeding significantly affected perinatal mortality in Limousin and Hereford animals. Effects differed by parity in Limousins. Inbred first-parity Angus dams had a greater incidence of dystocia. Although the effects of inbreeding were some-times significant, they were small and are unlikely to make a large financial effect on commercial beef production in Ireland.     

Effect of paratuberculosis on culling, milk production, and milk quality in dairy herds

OBJECTIVE: To determine the effect of paratuberculosis on culling, milk production, and milk quality in infected dairy herds. DESIGN: Cross-sectional study. ANIMALS: 689 lactating dairy cows in 9 herds. PROCEDURE: Milk, blood, and fecal samples were obtained from all cows. Fecal samples were evaluated via mycobacterial culture. Serum samples were tested with a commercially available ELISA for antibodies against Mycobacterium avium subsp paratuberculosis, and preserved milk samples were tested with an ELISA for antibodies against M paratuberculosis. Mixed effect and proportional hazards models were used to determine the effect of paratuberculosis on 305-day milk, fat, and protein production; somatic cell count linear score; and the risk of culling. RESULTS: Cows with positive results of bacteriologic culture of feces and milk ELISA produced less milk, fat, and protein, compared with herdmates with negative results. No difference in 305-day milk or fat production was detected in cows with positive results of serum ELISA, compared with seronegative cows. The 3 survival analyses revealed that cows with positive results of each test were at higher risk of being culled than cows with negative results. Paratuberculosis status, as determined by use of all 3 diagnostic tests, was not associated with milk somatic cell count linear score. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that for the 9 herds in this study, paratuberculosis significantly decreased milk production and cow longevity.     

Comparison of methods to evaluate the energy supply in dairy herds

Different methods to evaluate the nutritional and metabolic status in dairy herds are available. The aim of this study was to evaluate three different methods to assess the energy status of the herd: 1) the calculation of the energy balance of the herd with a new method based on the Swiss standard calculations, 2) the "efficiency of the feeding management" based on milk yield and milk protein content (%) obtained from DHI data, and 3) the percentage of cows per herd with an average milk yield (16-25 kg/day), but a low milk protein (< 3.2 %). The study included data from 47 farms enrolled in the herd reproduction survey program of the University of Berne, with a total of 653 cows included in one winter period. A correlation could only be seen between methods two and three. It is concluded that it is insufficient only to calculate the ration as an estimation of the energy status of the herd. A rough calculation of the ration is necessary to have an idea on the energy density. But the calculated ration seems to be considerably different from the amount of energy and nutrients of the diet finally absorbed by the cow. As the ingested ration is relevant for milk production and animal health, the relationship between milk yield and milk protein content as well as the percentage of cows with milk protein < 3.2% are considered to provide good information about the efficiency of the feeding management in dairy herds.     

Somatic cell counts, mastitis and milk production in selected Ontario dairy herds.

Somatic cell counts were performed monthly on bulk tank milk samples for all producers in the Ontario counties of Hastings, Lennox/Addington and Prince Edward throughout 1978 and 1979. Other data were obtained via a structured questionnaire and from the records of the Ontario Milk Marketing Board. Many producers have not adopted practices that have been advocated for the integrated control of mastitis. For example, 43.3% of producers surveyed used single service paper towels, 63.3% regularly used teat dip and 56.5% dry cow therapy. The mean of the average monthly somatic cell count for all producers for 1978 was 621.1 x 10(3) cells/mL. This latter value was used to divide the producers into case (higher than average) and control (lower than average) groups. Control herds averaged 95.9 liters more shipped milk per cow per month than case herds. Milk from control herds averaged 0.22 percentage points higher than case herds for each of average fat and lactose, and 0.16 percentage points higher for protein. The linear regression of monthly shipped milk on the respective monthly bulk tank somatic cell count indicated a loss of 13.26 L/cow/month for each 100,000 increase in somatic cell count.     

Fertility, somatic cell count and milk production in Swedish organic and conventional dairy herds

The share of organic dairy production in EU is increasing and this study describes the herd structure and cow performance in organic and conventional dairy production systems in Sweden. The data included records from 2 902 718 lactations, collected in organic (n = 471) and conventional (n = 13 976) herds between 1998 and 2005. Compared with conventional herds, the organic herds were larger and increased more rapidly in size. The replacement rate was slightly lower in organic herds and fewer Swedish Holsteins were used. The statistical analysis of cow performance in the first three lactations showed lower milk, fat and protein production in organic herds, but the increase in production from first to second lactation was larger when expressed in kg milk. Fertility was better for organically managed cows compared to conventionally managed cows, but the somatic cell count (SCC) was higher. However, at a given production level the fertility was slightly worse in organic herds while there was no difference in SCC. No interactions of importance were found between production system and breed for any trait.The results showed that organic and conventional dairy production differed regarding herd structure and cow performance. However, the differences in fertility and SCC found were to a high extent explained by the lower milk yield in organic production and no breed was found to perform better in either system.     

Comparison of cephalonium alone and in combination with an internal teat sealant for dry cow therapy in seasonally calving dairy cows

AIM: To assess the effect of combining an internal teat sealant (ITS) and a long-acting cephalonium-based dry cow therapy (DCT) on the prevalence of cows with a somatic cell count (SCC) >150,000 cells/mL 60–80 days after calving, and the incidence of clinical mastitis diagnosed by farm staff in the first 100 days after calving.

METHODS: Cows from a spring-calving, pasture-based, dairy farm in the South Canterbury region of New Zealand were randomly allocated to receive cephalonium DCT (n=289) or cephalonium and internal teat sealant (n=304) at the end of lactation. Cows were inspected twice daily by farm staff during the dry period and following calving for signs of mastitis. Individual SCC were determined from herd tests conducted in the previous lactation and following calving. Logistic regression models were used to determine relationships with the prevalence of cows with a SCC >150,000 cells/mL after calving, and survival analysis was used to model time to the first case of clinical mastitis following calving at the cow and quarter level.

RESULTS: The OR for a cow with a SCC >150,000 cells/mL after calving, including age and individual SCC in the preceding lactation in the model, was 0.53 (95% CI=0.32–0.89) for cows treated with combination therapy compared to cows receiving cephalonium (p=0.017). At the cow level, including age and preceding SCC in the model, the hazard ratio for diagnosis of clinical mastitis by farm staff in the first 100 days of lactation was 0.60 (95% CI=0.39–0.98) for cows treated with combination therapy compared to cows receiving cephalonium (p=0.04). At the quarter level, the hazard ratio for diagnosis of clinical mastitis, with age included in the model, was 0.41 (95% CI=0.23–0.74) for the combination therapy compared to cephalonium alone (p<0.001).

CONCLUSIONS: The combination of internal teat sealant and cephalonium DCT was more effective than cephalonium alone at reducing clinical mastitis diagnosed by farm staff in the 100 days after calving, and the prevalence of cows with a SCC >150,000 cells/mL 60–80 days after calving.

CLINICAL RELEVANCE: This study adds to the evidence that the prevention of intra mammary infections throughout the dry period and up to calving by using combination therapy is important in reducing the incidence of farmer-diagnosed clinical mastitis and prevalence of cows with a SCC >150,000 cells/mL 60–80 days after calving.     

Participatory Livestock Farmer Training for improvement of animal health in rural and peri-urban smallholder dairy herds in Jinja,Uganda

Within the framework of a research project investigating methods to decrease mastitis incidence, farmer groups for participatory training in a modified Farmer Field School approach were initiated in order to improve animal health and farmer knowledge in mastitis control technologies in smallholder dairy farms in the Jinja district of Uganda. Two peri-urban groups and one rural group met for common learning and training two hours per fortnight during a 12-month period, facilitated by two local extension agents together with one or two scientists from Makerere University. Farmers rotated each time between farms owned by group participants, which demanded mutual trust, openness and respect. From their own assessment the farmers felt they had improved their milk production and reduced mastitis incidence on their farms. In an evaluation workshop, they articulated how they had built up common knowledge and experience from training in systematic clinical examination of animals, evaluation of the farm environments, and identification of improvements. Much of the acquired new knowledge was about basic dairy cow management and husbandry practices. In addition, they gave examples of how they were now used as resource persons in their local communities. Principles of learning and empowerment are discussed.     

A randomised controlled study to assess the effects of an extension programme on the 6 week in-calf rate of seasonal calving,pasture-based dairy herds in New Zealand

The aim of this study was to quantify the effect of participation by New Zealand dairy farmers in a year-long extension programme designed to improve herd reproductive performance. This was estimated by comparing, over two successive years, the proportions of cows becoming pregnant during the first 6 weeks of the seasonal breeding programme (6 week in-calf rate) in herds involved in a full participation group (treatment), with herds in an actively monitored control group or a passively monitored control group. Possible interactions between treatment and various biophysical and socio-demographic factors were also assessed. Multivariable modelling was used to determine the effect of treatment on 6 week in-calf rate, adjusting for design factors (study year and region). It was estimated that the 6 week in-calf rate was 68% (95% confidence interval 65–67%) in the treatment group of farms that participated in the extension programme compared with 66% (95% confidence interval 67–69%) in the actively monitored control group of farms that did not participate in the extension programme (P = 0.05); thus the risk difference was 2.0% (95% confidence interval 0.0–3.9%). No significant interactions were found between treatment and region, study year or any of the biophysical and socio-demographic variables on the 6 week in-calf rate (P > 0.05). There was no significant difference in the 6 week in-calf rate between the actively and passively monitored control groups (P = 0.56). It was concluded that enrolment in the extension programme improved the 6 week in-calf rate, and that the treatment effect was not modified substantially by region, study year or any of the biophysical and socio-demographic variables assessed.     

Effect of meloxicam administration after calving on milk production,acute phase proteins,and behavior in dairy cows

Calving is an intrinsically risky process that can cause welfare and economic problems. The objective of this study was to assess the effect of the nonsteroidal anti-inflammatory drug meloxicam on various physiological and behavioral measures which can be related to pain in cattle. Sixty Friesian dairy cows from first to sixth parity were studied around calving and were randomly allocated into 2 homogeneous groups relative to parity and treated with either meloxicam or a placebo after calving. Treatments were administered on average 3.4 hours after calving, within a maximum of 6 hours. Calf positions at calving and calving assistance (unassisted or easy manual pull) were recorded. Milk production, rectal temperature, and activity (calculated as the number of steps per hour) were measured on each cow. From a subsample of 20 cows, haptoglobin (Hp) and serum amyloid A (SAA) concentrations were also obtained. The following behaviors were observed on video recordings: posture, changing posture, location of cow in pen, feeding, and tail up behaviors 2 days before and after calving. Statistical analysis was carried out with the SAS software using MIXED or GENMOD procedures. Most variables showed a parity and/or time effect around calving. This study did not demonstrate any significant effect of meloxicam on milk production or on acute phase responses of Hp and SAA. However, postcalving activity was significantly increased in meloxicam-treated heifers.     

Aetiology and prevalence of subclinical mastitis in dairy herds in peri-urban areas of Kigali in Rwanda

Tropical Animal Health and Production - The aim of this cross-sectional study was to evaluate the prevalence of subclinical mastitis (SCM) and associated risk factors in dairy cows in peri-urban...