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The effect of a multimineral preparation on the health and growth of spring born, dairy calves was investigated on four New Zealand pastoral farms. Calves were randomly allocated injections within 24 hours of birth, 35 days and 70 days after birth. Injections contained 40 mg zinc, 10 mg manganese, 5 mg selenium, 15 mg copper and 5 mg chromium per ml (Multimin+Se+ Cu+Cr Cattle, Virbac South Africa) at 1 ml/50 kg body weight. Morbidity, mortality from natural challenge and growth rates were recorded for 140 days. There were no differences in morbidity and mortality within 48 hours of birth for treated calves compared with controls, P=0.192. Morbidity and mortality were highest at 3-35 days (7.5 per cent [95 per cent CI 5.00 to 9.99] treated calves sick and 15.6 per cent [95 per cent CI 12.48 to 18.73] controls sick, P<0.001). For this period, mortality was lower at 4.4 per cent (95 per cent CI 2.49 to 6.41) treated calves and 10.4 per cent (95 per cent CI 7.78 to 13.03) controls, P<0.001. Allowing for potential confounders, the adjusted OR of treated calves scouring between 3 and 35 days was 0.44 (95 per cent CI 0.24 to 0.82, P=0.009). Allowing for potential confounders, from 0 to 140 days a second model predicted treatment approximately halved the probability of morbidity and mortality (P<0.001). There was no difference in the daily rate of gain (0.67 kg/day [95 per cent CI 0.66 to 0.67] for treated calves)., Competing Interests: Competing interests: The authors wish to draw the attention of the Editor to the following facts which may be considered as potential conflicts of interest and to significant financial contributions to this work. AB and MS are employees of Dairy Excellence Centre, owned by Vetlife Ltd; MW is an employee of Virbac NZ. RAL is employed by Massey University, NZ., (© British Veterinary Association 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

This study investigated the effects of housing primiparous lactating Holstein heifers either in cubicles with butyl rubber mats, cubicles with thicker mattresses filled with chopped rubber, or straw yards, and supplementing them with methionine for the first 13 weeks of lactation on the rates of growth of their hoof horn and the conformation of their feet. Overall, the rate of growth of the hoof horn increased significantly after calving but the rate of wear did not increase. In contrast, the type of housing had no significant effect on the growth of the hoof horn, but the heifers in straw yards had significantly lower rates of lateral horn wear. The changes in growth and wear rates resulted in changes in hoof conformation, including the toe angle and the width of the bearing surface, which suggested that heel bulb hypertrophy occurred after the heifers had been moved from soft underfoot conditions on to concrete. Providing 115 per cent of their estimated methionine requirements had no significant effect on the rates of growth and wear of the hoof horn.

High concentrations of dietary nitrogen have been associated with reductions in the fertility of dairy cows, but the evidence is not conclusive and many studies have shown little or no effect. This paper reviews recent investigations of the effect of rapidly degradable sources of nitrogen on parameters of fertility, and concludes that high levels of dietary nitrogen do not routinely reduce fertility, even at intakes above those in normal dairy cow diets. It also concludes that cows may be able to adapt to high nitrogen diets so that diets that may reduce their fertility when introduced at critical periods, for example, when they are inseminated, do not reduce it when introduced at an earlier stage.

Synchronisation, using a combination of gonadotrophin-releasing hormone and prostaglandin F2alpha injections, is commonly used to control the reproductive cycle of dairy cows. A simple model that could predict the monetary return from synchronisation would be a valuable tool in determining whether it would be worthwhile. This study used data from three controlled clinical trials to investigate the effects of six factors (interval between calving and synchronisation, 21-day submission rate, number of cows synchronised, average age, pregnancy rate of non-synchronised cows and season) on the return from synchronisation. The results suggests that the herd's submission and pregnancy rates, the time between calving and synchronisation, and the number of cows synchronised can all significantly affect the return from synchronisation, but only time since calving significantly affected the return in all three trials. They also suggest that there is no simple linear relationship between these factors and the return from synchronisation.

As part of a study of the development of hoof horn haemorrhages in first-lactation heifers, measurements were made of acute phase reactants to investigate the link between the acute phase response and the development of the haemorrhages. Over a period of two years, blood samples were taken from two separate groups of heifers, weekly in the three weeks before they calved and then twice weekly until eight weeks after calving. Plasma total protein, albumin, fibrinogen, haptoglobin, seromucoid and serum iron and caeruloplasmin were measured and the relationships between the peak concentration (or activity) or the area under the curve of each acute phase reactant and the peak scores for sole or white line haemorrhages were assessed by linear regression. The results suggested that the development of the hoof horn haemorrhages observed in the study was not accompanied by an acute phase response, and the haemorrhages were therefore not primarily caused by endotoxicosis. The diets and husbandry systems used were typical of dairy farms in the UK and the results therefore suggest that a significant proportion of hoof horn haemorrhages observed in UK dairy cows may not be caused by endotoxicosis.

Diseases of the hoof horn are the most common cause of lameness in the UK dairy herd, and diet, particularly starch intake, is commonly implicated in their development. This study assessed whether replacing starch carbohydrate with sugar beet pulp, in a diet containing 50 per cent of the dry matter as forage, would significantly reduce the development of hoof horn haemorrhages in dairy heifers after calving. It also investigated the effect of replacing wood shavings as cubicle bedding with chopped straw. The heifers fed the high-fibre diet had a significantly lower yield of milk protein and a significantly higher yield of milk fat than the heifers fed the high-starch diet, indicating that the change of diet had affected rumen fermentation. However, the change had no significant effect on the development of hoof horn haemorrhages. The change of bedding material also had no significant effect on the development of hoof horn haemorrhages.

The relationship between milk urea concentration and the fertility of dairy cows was examined in two studies. The first examined the relationship between bulk milk urea concentration and overall herd fertility, using data collected from 250 herds in the UK. There was no relationship either between bulk milk urea concentration and fertility, or between changes in bulk milk urea concentration and fertility. The second study compared the relationship between the milk urea concentration five days after service, and the fertility of individual cows on 11 UK dairy farms. There was no significant difference between the milk urea concentration of the cows that became pregnant and those that did not.

The efficacy of three non-antibiotic products (copper sulphate, formalin and peracetic acid) was compared with the efficacy of erythromycin, when the four substances were applied in footbaths for the treatment of cows with digital dermatitis. The cows were divided into four groups on the basis of their current housing and randomly allocated to one of the four treatments. Cattle allocated to the non-antibiotic treatments were footbathed daily for seven days, but the cattle treated with erythromycin were footbathed for two days only. Complete records were obtained for 252 lesions from 169 cows. There were significant reductions in the lesion scores of all four groups, but there was no significant effect of treatment and no significant interaction between treatment and time.

Hock damage is one of the most common traumatic injuries suffered by dairy cows, but most hock injuries should be avoidable. This study investigated the effect of housing system on the development of hock damage in first lactation Holstein heifers. After calving, 60 heifers were randomly allocated to either straw yards, cubicles with butyl rubber mats or cubicles with mattresses filled with chopped tyres. The hocks of these heifers were examined in the first week after calving (week 1) and in weeks 6, 12 and 26 of lactation. Hock damage was scored as either 1 (hair loss only) or 2 (all other damage). Heifers housed in cubicles with mats had significantly worse lesions at week 26 than at week 1, while there was no change in heifers housed in cubicles with matresses, and heifers housed on straw had significantly lower lesion scores. Additionally, heifers with no lesions at calving were significantly more likely to develop lesions when kept on mats than heifers kept on straw or mattresses. These data suggest that replacing mats with mattresses in cubicles can result in a significant reduction in traumatic hock injury.

Measurements of the conductivity of quarter milk samples were made in 31 cows in a 70-cow herd in southeast England, for a period of 15 weeks. Over this period, 42 per cent of cow-weeks and 20 per cent of quarter-weeks had an increase in quarter milk conductivity of 10 per cent of more compared with the mean conductivity of the previous 14 milkings. Fourteen per cent of quarter-weeks had an increase in conductivity of 15 per cent or more. The geometric mean somatic cell count (cell count) was higher in quarter-weeks with a 10 per cent or greater increase in conductivity than in quarter-weeks with a conductivity change of less than 10 per cent. At a conductivity threshold of 10 or 15 per cent and a cell count threshold of 200,000 or 400,000 cells/ml the specificity of this system was estimated to be 85 to 92 per cent, the sensitivity 40 to 54 per cent, the negative predictive value 87 to 93 per cent and the positive predictive value 33 to 55 per cent. The positive predictive value of the individual quarter milk conductivity was insufficiently accurate to be used as the sole criterion for the selection of quarters for early antibiotic treatment.

The currently recommended intake of vitamin E for dairy cows is based on the prevention of nutritional myopathy, a calf disease. However, it is likely that the vitamin E requirement of the modern dairy cow is very different from that of a calf. This review of the literature investigates the effect of vitamin E supplementation on the health and fertility of the dairy cow. Supplementation of high levels of vitamin E (at least 1000 iu per day) during the dry period and early lactation can reduce the incidence of mastitis, possibly because of an increase in immune system activity and function, but there appears to be little benefit of supplementation on infectious diseases other than mastitis. The evidence for a response in the reproductive system is more equivocal. In herds with a history of selenium deficiency and a high incidence of retained fetal membranes, supplementation, in conjunction with selenium, can reduce retention, but the evidence for an effect of supplementation on other reproductive diseases, such as cystic ovarian disease and metritis, is based on a very limited number of cases. The literature suggests that the current recommendations for vitamin E are inadequate. In particular, it suggests that the current linking of requirement to dry matter intake is incorrect, because vitamin E requirement is probably at its highest when intake is at its lowest However, the majority of the data on which this conclusion is based, come from North America where cows will encounter significantly different levels of oxidative stress from cows in the EU.

One hundred and eleven dairy cows with digital dermatitis, on six commercial farms, were used to test the efficacy of a footbath containing erythromycin for treating the condition. Four days after 55 of the cows had walked through the footbath after two successive milkings their lesions were significantly less active and painful than those of the 56 untreated cows. These 56 cows were then treated in the same way and both groups were re-examined seven days later. There were no significant differences between the clinical signs observed in the two groups, and the benefits of the treatment had persisted for the 11 days of the trial.

Increasing a cow's intake of dietary protein intake can increase its milk production, but can also reduce its fertility. This paper reviews the effects of increasing dietary protein on the fertility of the dairy cow, and the mechanisms that may produce them. The effects vary widely, but all stages of the reproductive cycle from the return to cyclicity after parturition, to the survival of the embryo, may be affected. However, the underlying cause of the link between protein intake and fertility is unclear. Fertility could be reduced by a direct toxic effect of protein breakdown products, but alternatively the increased energy demand for their metabolism could be responsible. The effect of protein degradability is also uncertain. Excess rumen degradable protein is commonly associated with reduced fertility, but similar effects are produced by diets that contain excess rumen undegradable protein. Increasing the intake of protein of all degradabilities has significantly different effects on blood biochemistry than a reduction in the intake of energy, suggesting that not all the effects of protein are due to energy imbalance. The primary site of action of the effect is also unclear. Limited evidence suggests that it is localised to the reproductive system, but effects on the pituitary and hypothalamus, as well as the ovary and uterus, have all been postulated. It is also uncertain what toxic principle is involved. Ammonia, nitrate and urea have all been suggested, but there is no conclusive evidence. Although a high protein intake has been postulated to have an effect on fertility for over 30 years, the evidence remains inconclusive, and the aetiology and pathogenesis of the effect remain obscure.

A Jersey herd was investigated following a decrease in milk yields. The cattle were permanently housed and fed a complete diet in four groups on the basis of yield. They were generally healthy, but the dry cows and many of the milking cows were over fat. The plasma concentrations of beta-hydroxybutyrate and glucose were normal, but the activities of aspartate aminotransferase and glutamate dehydrogenase and the concentration of non-esterified fatty acids were high. Fatty liver syndrome was diagnosed. All the dry cows were condition scored and placed into one of three dietary groups according to their score. They were exercised in an outdoor paddock and entered the pre-calving feeding group at least two weeks before calving; 75 per cent of them achieved a condition score of less than 3, and most of them produced normal milk yields. Thirty cows which had developed signs of fatty liver syndrome were paired and one of each pair received an injection of 640 mg of recombinant bovine somatotrophin. The yield of the treated cows was significantly higher (P < 0.05) for the first two weeks after the injection. The treated cows had higher plasma concentrations of beta-hydroxybutyrate and non-esterified fatty acids and lower plasma urea concentrations seven days after the injection. No other biochemical parameters were affected.

The literature on the treatment of retained placenta and its effects is reviewed. Manual removal, the oldest and commonest method of treatment, benefits parlour hygiene but may adversely affect the cow. The use of collagenase may allow manual removal without such side effects. Ecbolic drugs are often ineffective, both as prophylaxis and treatment for the condition. They are most effective within one hour of parturition, particularly after a caesarean section in which tocolytic drugs have been used. Endometritis is a very common sequel to retained placenta. Antibiotics and oestrogens have been used to treat, control or prevent the condition, but they are not routinely effective and may have deleterious side effects. Gonadotrophin releasing hormone and/or prostaglandins have been used to reduce the deleterious effect of retained placenta on fertility, but the results obtained have been inconsistent.

The literature on the effects and causes of retained placenta in the cow is reviewed. On a herd basis the condition can adversely affect milk yield and fertility, but on an individual cow basis the effects are unpredictable. The aetiology of retained placenta has been extensively studied and many causal factors have been implicated, but little is known of how many of them cause the condition. As a result its prevention and prediction is uncertain, primarily because of the lack of knowledge of the normal process of placental release. Vascular changes and uterine contractions play a role in placental release, but current opinion suggests that the primary cause of retained placenta is the retention of the feto-maternal union. Release only occurs after a process of maturation, which involves hormonal and structural changes. The factors which are thought to influence these changes, and thus cause the condition, are discussed.

Recombinant bovine somatotrophin was used in addition to conventional therapy to treat a sample of post-calving cows in a herd suffering a high incidence of fat cow syndrome. Somatotrophin was also given to cows before they calved. There were no significant differences between the treated and untreated groups in the plasma concentrations of glucose, beta-hydroxybutyrate, albumin, total protein or calcium. Significant decreases in mean plasma urea concentration were observed in the pre-calving cows seven and 10 days after treatment with somatotrophin, and a significant decrease in mean plasma urea concentration was also recorded in post-calving cows with the fat cow syndrome. There was no evidence that somatotrophin, with its many potent actions in cows with acetonemia, exacerbated clinical ketosis. The authors' subjective clinical impression was that somatotrophin was helpful in the treatment of cows with the fat cow syndrome.