Effects of diseases on reproductive performance in Swedish Red and White dairy cattle

The objectives of this study were to evaluate the effect of diseases on days open (DO), days to first breeding (DFB) and days from first breeding to conception (DFBC) using survival analysis models, and to assess the significance of the sire component and its possible confounding effect. The data consisted of a random sample of 20% of all herds enrolled in Swedish recording system and using 100% artificial insemination with at least 15 Swedish Red and White cows calving in 1991. The follow-up period was from 45 to 145 d after calving. After editing, the data sets had 23,927, 28,197, and 22,089 cows for days open, days to first breeding, and days from first breeding to conception, respectively. The Cox models included parity, calving season, cow milk production and age at first calving as fixed effects, and herd and sire as random effects. Ten disease groups were considered as possible risk factors for the reproductive traits. Disease groups were treated differently if they occurred before or after 45 d postpartum. Diseases occurring in the first 45 d after calving were treated as time-independent covariates and diseases occurring after day 45 were treated as time-dependent covariates for days open and days to first breeding. The percentages of censored cows were 35% for days open, 19% for days to first breeding, and 33% for days from first breeding to conception. Days open increased in cows with dystocia, stillbirth, retained placenta, metritis, or other diseases occurring in the first 45 d after calving, and in cows with metritis, mastitis, or other diseases occurring after 45 d. Days to first breeding increased in cows with stillbirth, retained placenta, milk fever, mastitis, foot and leg problems, or other diseases occurring before day 45, and in cows with metritis, mastitis, foot and leg problems, or other diseases occurring after 45 d. Days to first breeding decreased in cows treated for ovulatory dysfunctions either before or after 45 d. Days from first breeding to conception increased in cows with dystocia, stillbirth, retained placenta, metritis, or ovulatory dysfunctions occurring before first breeding, and in cows with mastitis occurring after first breeding. Although the additive genetic components were significant for all traits considered, the sires did not act as confounders because only a small amount of variability for the traits considered in this study was explained by the sires, with estimated heritabilities of 2% on the logarithmic scale and from 3 to 4% on the real scale.     

Use of ultrasound in the reproductive management of dairy cattle

The significant decrease in fertility observed in dairy cattle during the last few decades and increasing requirements by the farmers have made a regular control of reproduction indispensable to urgently identify and solve potential problems affecting reproductive efficiency. Traditionally, the main diagnostic methods used for reproductive control in cattle included rectal palpation, inspection of vaginal discharge and vaginoscopy. Since the 1990 s, the use of ultrasound (US) has become a common diagnostic method as a result of the new advances made in the development of US scans: smaller size, high level of autonomy, high image quality and accessible prices. Ultrasound improves accuracy in the diagnoses of stages of the oestrous cycle, ovarian and uterine pathologies, and pregnancy diagnosis. In addition, it facilitates the diagnosis of alterations during pregnancy (embryo mortality, foetal malformations, etc.) and helps determining foetal sex from day 55 of pregnancy.     

Greater participation by veterinarians in the reproductive management of dairy cattle

A program involving greater veterinary participation in detection of estrus and artificial insemination of cattle was evaluated in a 700-cow dairy herd from January 1987 through August 1988. Previous reproductive performance was below normal. First-service pregnancy rate from artificial insemination was 42%, and mean number of nonpregnant days for the cows was 120. Between postpartum days 55 and 62, all cows with functional corpus luteum assessed by rectal palpation were administered prostaglandin each Monday morning. Return visits were made to the herd each Thursday and Friday to observe cows and to inseminate those in estrus. On the other 5 days of the week, the owner or his employees inseminated all cows in estrus. The first-service pregnancy rate for 842 cows observed in estrus and inseminated by the veterinarian was 59%. The pregnancy rate for cows inseminated by the owner and his employees increased from 42% to 50%. The mean number of nonpregnant days for all 700 cows decreased from 120 to 98 days, resulting in approximately $46,000 of increased income for the dairyman or approximately a 4 to 1 return on investment in veterinary service. Results indicate that veterinarians could improve herd reproductive performance and solve chronic herd breeding problems by more actively participating with their clients in estrus detection and artificial insemination programs in cattle. The program allows practicing veterinarians an opportunity to observe cows for estrous behavior, establish their own pregnancy rate data, demonstrate to owners the importance of observing primary signs of estrus, and teach expert artificial insemination techniques.     

Some important teat diseases of dairy cattle

Extract

Teat diseases, are a common and somewhat neglected problem of dairy cattle medicine. The effects of teat diseases on milk production are difficult to measure but they can undoubtedly be classed amongst the diseases of economic importance to the dairy industry of New Zealand.     

Economic and reproductive consequences of retained placenta in dairy cattle

The financial losses due to retained placenta in Dutch dairy cattle were estimated by using two different methods of calculation. A data-set containing the birth records of 160,188 Meuse-Rhine-Yssel cows provided data on the reproductive performance of cows with and without retained placenta. The fertility of cows after retention of the placenta appeared to be affected. An economic calculation made by adding the losses due to increased calving interval, increased culling rate, loss of milk production and the costs of veterinary treatment and drugs revealed that the total loss due to retained placenta was 471 pounds per year for a 100-cow farm with an average incidence of the condition (6.6 per cent). For a 'problem' farm with a 30 per cent rate, the loss was 2139 pounds per year. A computer farm simulation model, based on a stochastic determination of events, was used to make calculations for circumstances closely resembling those on farms. A 6.6 per cent rate of retained placenta caused a small but significant decrease in net return on labour and management; however, a 30 per cent rate caused highly significant changes. The economic effects of retained placenta were similar in magnitude in herds of high or low productivity and high or low fertility. Sensitivity analysis showed that the greatest financial losses were caused by loss of milk production, followed by the number of animals suffering from complications. The financial losses in herds with an average rate of retained placenta were thus of limited economic importance and therapeutic measures alone should be adequate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biosecurity for mammary diseases in dairy cattle.

As US dairies grow ever larger and obtain replacement animals from a wide geographical area, biosecurity will loom ever more important as a means of controlling mammary disease. To prevent costly outbreaks of contagious mastitis, introduced animals must be screened for contagious IMI before the resident herd is exposed to them. Screening programs must be instituted to detect the appearance of contagious IMI as soon as possible after introduction has occurred. Most importantly, 40 years of knowledge regarding the on-farm control of contagious mastitis (now known as with-in-herd biosecurity) must be dusted off and implemented with renewed vigor to prevent the rampant spread of contagious mastitis.     

Associations between use of electric cow-trainers and clinical diseases, reproductive performance and culling in Swedish dairy cattle

The aims of this follow-up study were: (a) to evaluate the role of ECT technology as a risk factor for several diseases; and (b) to determine if the effects of these diseases on cows' reproductive performance and as risk factors for culling are influenced by exposure to ECTs. Diseases considered were retained placenta, metritis, ketosis, cystic ovaries, silent heat, milk fever, clinical mastitis, and foot and leg problems. We used historical and contemporary controls (with control herds selected to match the experimental herds for size and location). Data consisted of 10264 Swedish Red and White (SRB) and 5461 Swedish Friesian (SLB) lactation records in 150 herds of which 33 used cow-trainers. Logistic regression was used to estimate the effects of parity and exposure to electric cow-trainers on the risks of diseases and the effects of diseases and exposure to electric cow-trainers on risk of culling. The least-squares procedure was used to estimate the effects of diseases on reproductive performance.

The dominant effects associated with use of electric cow-trainers were an increased risk for silent heat, clinical mastitis, ketosis and culling relative to cows in herds not using cow-trainers. Diseases had negative effects on reproductive performance and the effects were larger for cows in herds using cow-trainers. In herds using electric cow-trainers, the largest increase in the interval from first service to conception (58 days) was caused by the occurrences of silent heat, cystic ovaries and the combination of two or more diseases. Retained placenta, metritis, cystic ovaries, clinical mastitis and a combination of two or more diseases increased the risk of culling about two times relative to healthy primiparous cows with the increase being greater for cows in herds using cow-trainers. Silent heat did not increase risk of culling in control groups, but was the largest risk factor for culling in the exposed group. We concluded that exposure to electric cow-trainers increased the incidence risk of silent heat, clinical mastitis, and ketosis and changed silent heat from a neutral disease with respect to culling to a major risk factor. Finally, exposure to cow-trainers increased the general negative effect of diseases on the cows' reproductive performance and risk for culling.     

Specific immunoprophylaxis of some viral diseases in cattle

Specific immunoprophylaxis has played a key role in prevention and control of animal infectious diseases for many years. Vaccines are commonly used to diminish economic losses in animal production caused by infectious agents. Currently, respiratory diseases are the main health problem in cattle. BHV1, BRSV and BVD-MD viruses are among the most important pathogens worldwide. They can cause a disease themselves or they can be one of many agents causing a respiratory syndrome. The following article describes the specific immunoprophylaxis of cattle viral diseases caused by such viruses.     

Mastitis effects on reproductive performance in dairy cattle: a review

The reproductive performance of dairy animals is influenced by several factors, and accumulating lines of evidence indicate that mastitis is one of the determinants. Most of the published information relating mastitis with reproduction has evolved based on retrospective approach rather than controlled clinical studies. The complex nature of both mastitis and reproduction could be a limiting factor for understanding their relationship in detail. In this review, we analyzed the available retrospective studies on the effects of clinical mastitis on reproductive function and explained the possible mechanisms by which mastitis affects reproduction in dairy animals.     

Improving calving management to further enhance reproductive performance in dairy cattle

The aim of this study was to develop a system for the monitoring of calving to both reduce perinatal morta1ity and improve dairy cow fertility by preventing the majority of post-partum reproductive pathologies. Eighty dairy cows were assigned to the protocol of calving monitoring using GSM (Global System for Mobile Communications) technology. The application of GSM technology and the proper management of calving facilities comprise reliable approaches for calving assistance and improvements in reproductive efficiency and neonata1 viability. Based on the results of this study, we advocate the use of GSM technology on large farms for intensive mi1k production.     

Biosecurity for gastrointestinal diseases of adult dairy cattle.

As biosecurity management strategies are developed and implemented to prevent introduction and spread of infectious diseases in cattle populations, it is informative to review principles of biosecurity from another livestock species in which these issues have been considered (e.g., swine) and compare these perspectives to the current situation for cattle. The authors follow a biosecurity risk-assessment model to identify important health hazards, evaluate risks, and present principles for implementing a cattle biosecurity program for important gastrointestinal health hazards of adult dairy cattle, after consideration of a swine biosecurity model.     

Dry period management and optimization of post-partum reproductive management in dairy cattle

Dry period and early post-partum management are decisive factors for fertility in lactating dairy cows. Previous studies have shown that decreased dry matter intake (DMI) and increased non-esterified fatty acids (NEFA) negatively affect fertility and subsequent milk production. The traditional dry period decreases DMI prior to parturition, resulting in a decrease in energy intake. A negative energy balance increases NEFA concentration, and increased NEFA may impair the immune system, especially by decreasing neutrophil function prior to parturition. Earlier studies have shown that post-partum health disorders, including retained placenta and metritis, were correlated with periparturient neutrophil function. In addition, decreased DMI is also linked to a reduced body condition score (BCS) in dairy cows. These events in the periparturient period negatively affect fertility. Some manipulation, such as shortening the dry period, may be a solution to increased DMI in the periparturient period, preventing post-partum disorders and subsequent fertility issues. This article aims to explain the effects of shortening the dry period on reproduction and early post-partum treatments to improve fertility. In addition, timed artificial insemination protocols will be discussed for use during the post-partum period to improve fertility in dairy cows.     

Incidence and risk factors for ketosis in grazing dairy cattle in the Cundi-Boyacencian Andean plateau,Colombia

Ketosis is a metabolic disorder that has an important impact on health and productivity in dairy cattle during early lactation. In Colombia, the incidence and risk factors for ketosis development have not been studied. The objectives of the present study were to determine the incidence of subclinical (SCK) and clinical ketosis (CK) and to determine the risk factors associated with ketosis within the first 6 weeks of lactation in dairy cattle in Colombia. A prospective cohort study was carried out. A convenience sample of 150 lactating dairy cows from ten commercial dairy farms in the Cundi-Boyacencian Andean plateau were tested weekly using a point of care device to measure β-hydroxybutyrate during the first 6 weeks of lactation. Incidence of SCK and CK was calculated. Risk factors were evaluated using a survey for each animal and for each farm. Potential risk factors were evaluated using a X² test, Relative Risk was calculated for significant variables by the X² test (P?≤?0.05) and these variables were included in the logistic regression model. Cumulative incidence of SCK was 25.33%, 3.33% for CK, and overall incidence of ketosis was 26%. In the logistic regression model, parity 3 or more, herd size >?150 animals, body condition score ≥?3, retained placenta, and metritis were determined as risk factors for ketosis. The results of this study confirm previous reports in which a high body condition score, increased parity, herd size, retained placenta, and metritis are associated with an increased risk of ketosis in stabled and grazing cattle.