Data were records of daily food intake and milk production, periodic measures of milk composition and all health and reproductive information from 140 multiparous Holstein cows involved in various experiments at the Agriculture Canada dairy research station in Lennoxville, Quebec. Energy concentrations of the total mixed rations were also available. Daily energy balance was calculated by multiplying the food intake by the concentration of energy in the diet and then subtracting from this quantity the expected (National Research Council) amount of energy required for maintenance (based on parity and body weight) and for milk production (based on yield and concentrations of fat, protein and lactose). Four energy balance traits were defined: (1) average daily energy balance within the first 10 to 100 days of lactation, (2) minimum daily energy balance, (3) days in negative energy balance and (4) total energy deficit during the period of negative energy balance. Health traits were the numbers of incidences of each of the following: (1) all udder problems, (2) mastitis, (3) all locomotive problems, (4) laminitis, (5) digestive problems and (6) reproductive problems. Reproductive traits were the number of days to first observed oestrous and number of inseminations. Phenotypic relationships between energy balance and health were investigated by regressing the energy balance traits on each health trait. Parity and treatment (according to the research trial that the cow was involved with) were also included in the model. Genetic parameters were estimated with restricted maximum likelihood and a model that included effects of parity, treatment and animal. Phenotypically, several significant (P<0.10) relationships between energy balance and health were observed. Cows with longer periods of negative energy balance had increased digestive problems. Cows with greater total energy deficit had more digestive problems and laminitis. Estimates of heritabilities for energy intake and milk energy were 0.42 and 0.12, respectively but estimates of heritability for all energy balance traits were zero. The low estimates for these traits may have been due to (1) low true additive genetic variance, (2) small amount of data, or (3) relatively few genetic ties among cows.

The main objective of this study was to estimate genetic correlations between fertility and production in first and second lactations as well as between fertility traits measured in the same way at different ages. The analyses were carried out for Swedish Red and White cows born from 1986 to 1996, in total about 578 000, 430 000, and 221 000 records in the heifer period, first lactation and second lactation, respectively. The fertility traits studied were: interval between calving and first insemination (CFI), interval between calving and last insemination (CLI), number of inseminations per service period (NINS) and number of treatments for reproductive disturbances (NREPT). Production was measured as the average of the energy-corrected milk yield from the second and third test-days in a lactation (ECM23). A linear, bivariate model that included effects of herd-year, month, age, and sire of the cow was applied. A relationship matrix containing sire and maternal grandsire of the sire was included. The (co)variance components for the random effects were estimated by use of a restricted maximum likelihood algorithm. The genetic correlations between fertility traits and production within first and second lactation were in the range of 0.1 to 0.3, all of them unfavourable. However, the genetic correlation between NREPT and ECM23 was close to zero within both lactations. The heritabilities, calculated without the herd-year variance included in the phenotypic variance, varied between 0.02 and 0.06 for the fertility traits with only minor differences between first and second lactation. The heritability of ECM23 was 0.35 in the first lactation and 0.28 in the second lactation. The genetic correlation between NINS during the heifer period and in first lactation was high, 0.7. The heritabilities for NINS and NREPT during the heifer period were very low, <0.01. In conclusion, there were only minor differences in inter-relationships between fertility and production in first and second lactation and the traits were negatively associated with each other. Based on the genetic correlation between NINS in the heifer period and NINS in first lactation, this study indicated that the traits at least partly are regulated by different sets of genes.

Milk synthesis and secretion have a high priority in the metabolism of the lactating cow. At peak lactation the nutrient needs of the mammary gland are of such magnitude relative to total metabolism that the udder has been compared with a parasite. The question arises: has the udder taken control of the cow? The aim of this study was to investigate whether the metabolic restriction point determining maximum milk output is localized at the level of the mammary gland itself or elsewhere in the body. The results indicate that the restriction point determining the maximum metabolic capacity is not localized in the udder as indicated by the ability of the mammary tissue to increase further its rate of milk secretion and therefore the maximum capacity is determined at the level of the whole body.

A method for inducing primary nutritional ketosis in dairy cattle was developed in order to evaluate a novel technique for the monitoring of the development of ketosis through to clinical disease state. Six freshly calved, multiparous Holstein-Friesian cows were given a 500 g/kg crude protein pellet in small but frequent meals through an out-of-parlour feeder in conjunction with an allowance of grass silage restricted to 20 kg wet weight per day. Development of the disease was monitored through clinical signs, body condition scoring, weight change measures and metabolic profiling of plasma samples with particular reference to beta-hydroxybutyrate, non-esterified fatty acid and glucose levels. Four animals within the disease model group became clinically ketotic with the remaining two animals showing signs of subclinical ketosis. A further four newly calved cows, which were maintained on a normal production ration to act as a control group, did not develop signs of ketosis.

In 1998, the European Community, the Region Wallonne, and the Province du Hainaut funded the project known as the Centre for the control of animal health and its management (CESAM). This project was initiated in the Hainaut province of Belgium to answer problems encountered by cattle producers. Its overall goal is the identification of stages in the entire bovine production process where economic efficiency can be increased. A part of this project aims principally at the study of the impact of health-related problems on dairy production. For this part of the project, 32 veterinarians and 51 farmers started collecting data in the field. The methodology for data collection was based mainly on the harmony between the farmer and the veterinarian. Therefore, several procedures were implemented to ensure adequate motivation of both farmers and veterinarians. Farmers note all events of their livestock using a list, which contains disease events, preventive treatments, reasons for culling, and management practices. A veterinarian visits farms monthly to validate collected data and to discuss specific problems. During these farm visits, veterinarians collect body condition scores on adult cows. Veterinarians record also information on health problems they encounter during their normal practice using an international health data recording nomenclature. A national organization provides unique animal identification system. Production data will be recorded and feeding practices, milking procedures and barn comfort indices will be regularly investigated. All data will be collected on pre-printed documents, scanned at CESAM and centralized in a relational computer database. Criteria to evaluate the quality of the proposed methodology are presented.

The present study was designed to examine the effects of selection for milk production as well as stage of pregnancy, on the grazing behaviour of dairy cattle. Subjects were 43 Holstein-Friesian cows from the Langhill Dairy Herd in Edinburgh. The herd consists of two genetic lines, one selected for high milk solids yield and a control line of average genetic index for milk solids yield. Animals of both genetic lines were observed as non-lactating heifers in 1992 and as first lactating and dry cows in 1993. Behaviour was recorded using scan-sampling procedures during seven observation periods at day and two periods at night. For analysis animals were grouped by their first lactation 305-day ECM (energy-corrected milk) yield for four observation periods during the day and for both night time observations animals were additionally grouped by stage of pregnancy. The majority of selected animals was in the high yielders’ group. In September 1992 and 1993 herbage intake on pasture was also investigated.

No significant influence of 305-day ECM yield on time spent grazing, lying or ruminating was found. The influence of stage of pregnancy was stronger, although results for heifers and cows were contradictory. During the day heifers which were closer to parturition spent less time grazing (P < 0.10 in two of three periods) and more time lying (P < 0.05 in one period) whereas lactating cows in late pregnancy spent more time grazing and less time lying (P < 0.01 and P < 0.10, respectively). High yielders had higher herbage intakes than low yielders but this result was significant for heifers only (P < 0.01).

Neutrophils perform a series of sequential functions to kill pathogens entering the body. The objective of this study was to investigate whether variation across cows in neutrophil function tests is related to milk production and energy balance. Blood samples from 37 Holstein-Friesian heifers were taken early morning after milking and prior to feeding. Each cow was sampled about 30 days before calving and at 30 and 100 days after calving. Three groups of neutrophil function tests were used: (i) measurement of phagocytosis of bacteria (with heat inactivated serum (no complement) or complete serum (complement and antibodies)); (ii) measuring production of reactive oxygen species (ROS) with 30, 100 or 300 nmol/l phorbol myristate acetate (PMA); and (iii) after ingestion of bacteria (Staphylococcus or Streptococcus). Milk production (including fat, protein and lactose percentage), live weight and food intake were recorded for the first 100 days of lactation and blood metabolic concentrations (non-esterified fatty acid, glucose, beta-hydroxybutyrate) were measured fortnightly (six samples per cow). Restricted maximum likelihood was used to estimate the regression coefficients of neutrophil function on these traits and cow identity was fitted as random effect to account for the repeated measurements. There was no effect of milk yield on the neutrophil function but animals with a higher food intake and a more positive energy balance had a lower ROS production across the lactation (PMA). Of the metabolic characteristics, (beta hydroxybutyrate was positively associated with the capacity of reactive oxygen species production (significantly for 300 nmol/l PMA and close to significant for 100 nmol/l PMA; P < 0.05) but negatively with reactive oxygen species after ingestion of bacteria. Hence, results from these two reactive oxygen species tests contradict each other. The results suggest that immune function is not affected by selection for milk yield, as long as food intake capacity is increased sufficiently.

Horizontal and vertical histological sections were prepared from cores taken post mortem at the sole/bulb junction of the distal surface of the claw of Holstein-Friesian cattle. Immunohistochemistry was performed on the sections using the Vectastain Elite® (anti-mouse IgG) peroxidase ABC method (Vector Laboratories Ltd) using 3, 3′-diaminobenzidine as substrate and mouse-derived primary antibodies against collagen I (bovine); collagen VII (human), collagen IV (human) and fibronectin (human). The sections were counterstained with toluidine blue. Captured colour images were prepared and transformed for presentation into 256 shades of grey using Openlab software (Improvion Ltd). The staining of the tissue sections, on comparison with negative controls, produced typical evidence of expression of collagens I, IV and fibronectin distributed throughout the upper dermis and dermal papillae. In contrast, the collagen VII signal was localized at the dermal/epidermal junction consistent with its rôle in the fibril network that attaches the basement membrane to the dermis. Collagens and fibronectin are recognized to have important rôles in maintaining structural integrity and function in other tissues. Following this identification, their rôle in the development of lesions in the bovine claw will be investigated further.