Stress responses to comparative handling procedures in sheep

The objective of this study was to compare some husbandry procedures on the base of physiological stress parameters and evaluate the welfare status in sheep. Forty ewes were used as the study material. Measurements were taken during several routine husbandry procedures such as milking, shearing, weighing, loading and hoof care. Data regarding time spent for each application, as well as heart and respiratory rates were recorded during the applications. Blood samples were taken 15 min before and after each application and malondialdehyde (MDA), glutathione-peroxidase (GSH-Px), cortisol T₃ and T₄ parameters were measured. In addition, changes in the same parameters between pre- and post-application periods were evaluated. According to the results, machine milking caused less stress than hand milking. No significant difference was seen between shearing methods for hand shearer or clipper; however, both applications caused stress in animals. The results for weighing methods of animals demonstrated significant differences in cortisol, T₃ and T₄ values in favor of traditional method. Cortisol, T₃ and T₄ levels were significantly higher in manual loading compared with loading by ramp. Regarding hoof care, all the examined parameters differed in favor of modern method. On the other hand, significant differences were determined between the stress parameters regarding pre- and post-applications. All values differed for hand milking while no significant difference was observed in MDA and T₃ values in machine milking group. Parameters in weighing groups changed significantly. For loading process, GSH, cortisol, T₃ and T₄ values differed in both treatment groups. With regard to hoof care, parameters except T₄ in laying group differed significantly. An increase occurred in minute-based measurements of heart and respiratory rates parallel to physiological data. The number of the respiratory rates during the applications differed except for the shearing process. All the parameters displayed significant differences between groups in terms of heart rates. Time spent for each application also differed between groups. Time saved for milking, shearing, weighing, loading and hoof care was 3.23 min, 4.37 min, 1.71 min, 7.85 s and 1.55 min, respectively. These results appear to provide a tangible advantage of using new husbandry methods to the breeders. It was concluded that using new methods in sheep husbandry procedures provided advantages in terms of saving time and reducing labor, as well as improved conditions for welfare of animals. In addition, it facilitated the routine works and flock husbandry.     

Characterization of antimicrobial resistant Salmonella Kinshasa from dairy calves in Texas

AIM: To determine the prevalence of antimicrobial resistance among Salmonella isolated from a central Texas dairy calf farm that raises animals for dairy-beef production. METHODS AND RESULTS: Salmonella isolates collected from 50 faecal samples were characterized for susceptibility to 20 antimicrobial agents. Seventy per cent of the faecal samples (35 of 50) tested positive for Salmonella, and high rates of resistance to the following drugs that are commonly used for treatment of bacterial enteritis in livestock were observed: ampicillin (88%), apramycin (83%), neomycin (86%), spectinomycin (91%) and oxytetracycline (90%). No resistance to the fluoroquinolone antibiotics was observed. The most prevalent Salmonella serotype was Kinshasha (22 of 35 samples), followed by Agona (4 of 35), Newport (3 of 35), Infantis (2 of 35), Montevideo (2 of 35), Lille (1 of 35) and Newington (1 of 35). The Kinshasa, Agona, Newport and Infantis serotypes all displayed resistance to ampicillin, chloramphenicol, streptomycin, sulphamethoxazole and tetracycline, and the penta-resistance phenotype was transferable to an Escherichia coli recipient strain. SIGNIFICANCE: Multi-drug resistant Salmonella in dairy calves pose a costly animal health problem and a potential risk to the public health. This study emphasizes the need for alternative, non-antimicrobial intervention strategies for the control of zoonotic pathogens.     

Effects of isovalerate supplements on morphology and functional gene expression of rumen mucosa in pre- and post-weaning dairy calves

Isovalerate supplements could stimulate rumen development by improving morphology and function of rumen mucosa, and then promote the growth of calves. This study was done to evaluate the effects of isovalerate supplements on morphology and functional gene expression of rumen mucosa in dairy calves. In total, 48 Chinese Holstein male calves with 15 days of age and 45.1±0.36 kg of BW were randomly assigned to four groups. The treatments were: control, low-isovalerate, moderate-isovalerate and high-isovalerate with 0, 3, 6 and 9 g isovalerate per calf per day, respectively. Supplementary isovalerate was hand-mixed into milk in pre-weaning calves and into concentrate portion in post-weaning calves. The study consisted of a 15-day-adaptation period and a 60-day-sampling period. Calves were weaned at 60 days of age. Three calves were slaughtered from each of the four treatments at 30, 60 and 90 days of age. The weight of body and stomach were measured, samples of ruminal tissues and blood were analyzed. Total stomach weight, total stomach to BW ratio, rumen wall and keratinized layer thickness, serum growth hormone and IGF-1 for both pre- and post-weaning calves increased linearly with increasing isovalerate supplements. Rumen to total stomach weight ratio, the length and width of rumen papillae, and serum β-hydroxybutyrate increased linearly for post-weaning calves. However, abomasum weight to total stomach weight ratio decreased linearly for both pre- and post-weaning calves. The relative messenger RNA expression for growth hormone receptor, IGF-1 receptor and 3-hydroxy-3-methylglutaryl-CoA synthase 1 in rumen mucosa increased linearly for post-weaning calves. Our results suggested that isovalerate supplements promoted rumen development in a dose-dependent manner. The optimum dose was 6.0 g isovalerate per calf per day.     

Weaning distress in dairy calves: Effects of alternative weaning procedures

The aims of this study were to describe the behavioural responses to weaning from milk in dairy calves, and to compare responses when calves were either weaned abruptly (removal of the milk-feeding system; n = 8 calves) or by substituting warm water for milk in the milk-feeding apparatus for the first 2 days after weaning (n = 8 calves). Calves provided water through the milk-feeding system after weaning seemed to substitute one liquid for the other; calves consumed approximately the same quantity of warm water after weaning (8 kg/day) as they had consumed milk before weaning (9 kg/day). All calves vocalized at weaning, but abruptly weaned calves vocalized at more than three times the rate of calves provided water through the milk-feeding system. On the third day after weaning, when neither treatment group had access to the milk-feeding system, the call rate was similar in the two treatment groups. The abruptly weaned calves were also more active at weaning, as indicated by an increased number of standing bouts compared to calves with continued access to the milk-feeding apparatus. The reduced response to weaning by the calves with continued access to the feeding routine may be due to the gut fill associated with the water intake or to other rewarding properties of the system (e.g. allowing calves to suck on a teat). In conclusion, dairy calves show a strong behavioural response to weaning, but providing calves continued access to the milk-feeding apparatus for 2 days after weaning reduces this response.     

Relationship between locomotor play of dairy calves and their weight gains and energy intakes around weaning

Play behaviour has been proposed as a measure of good welfare in growing animals and locomotor play by calves is often reduced after weaning off milk. Adjusting weaning age according to individual calves’ abilities to eat solid feed maintains energy intake and weight gain during weaning. We investigated the effects of this method of weaning on locomotor play of calves and the relationship between locomotor play and energy intake and weight gains. We measured the running behaviour of 56 Holstein heifer calves before and after weaning. Calves were housed in groups of eight, fed milk, grain starter and hay from automated feeders. Weaning began when their voluntary intake of grain starter reached either 200 or 400 g/day, and weaning was completed when starter intake reached either 800 or 1600 g/day. Before weaning, older calves ran less than young ones; and the duration of running correlated with weight gains and digestible energy intake. Immediately after weaning, digestible energy intake and locomotor play decreased but no correlation was observed between these variables. One week after weaning, the duration of running was correlated with both energy intake and weight gain. Digestible energy intake increased but locomotor play continued to decrease. The amount of running a calf does after weaning partly reflects energy intake and weight gain, supporting suggestions that locomotor play is good indicator of welfare and fitness of growing animals. However, the decline in locomotor play following weaning is not solely due to decreased energy intake.     

Effects of folic acid on growth performance,ruminal fermentation,nutrient digestibility and urinary excretion of purine derivatives in post-weaned dairy calves

This study evaluated the effects of folic acid (FA) supplementation on growth performance, ruminal fermentation, nutrient digestibility and urinary purine derivatives (PD) excretion in dairy calves. Forty-eight Chinese Holstein male dairy calves at 60 ± 3.2 d of age and 89 ± 5.9 kg body weight (mean ± standard error) were assigned to one of four groups in a randomised block design. Calves in control group were fed basal diet, calves in low FA, medium FA and high FA groups with 3.6, 7.2 and 10.8 mg FA per kg basal diet, respectively. The dietary corn silage to concentrate ratio was 50:50 (dry matter [DM] basis). DM intake and average daily gain (ADG) quadratically increased, and feed conversion ratio quadratically decreased with increasing FA supplementation. Ruminal pH linearly decreased, whereas total volatile fatty acids quadratically increased. The unchanged acetate-to-propionate ratio was due to the similar change in acetate and propionate concentration. Ammonia N content quadratically decreased. Digestibility of DM, organic matter, crude protein, ether extract, neutral detergent fibre and acid detergent fibre linearly increased. Activities of carboxymethyl cellulase, cellobiase, xylanase and pectinase linearly increased, but α-amylase and protease quadratically increased. Abundance of Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes linearly increased, but Butyrivibrio fibrisolvens and Prevotella ruminicola quadratically increased. Urinary total PD excretion quadratically increased. The results indicated that FA supplementation increased ADG, ruminal fermentation and nutrient digestibility with promoted ruminal microbial growth and enzyme activity, and the optimum dose was 7.2 mg FA per kg basal diet for calves.     

Effects of nickel supplementation on nutrient utilization,mineral balance,haematology and antioxidant status of crossbred dairy calves

BackgroundNickel has been identified as an important newer trace mineral playing essential role in animals however, its precise mechanism of action in the body is yet to be determined. Interaction of Ni with other essential minerals is suggested in reports limited to lab animals and needs to be explored further in large animals.AimThis study was conducted to study the influence of Ni supplementation at different levels, on minerals and health status of crossbred dairy calves.MethodTwenty-four Karan Fries crossbred (Tharparkar × Holstein Friesian) male dairy calves were selected based on body weight (137.09 ± 5.68) and age (10.78 ± 0.61) and were divided into 4 treatment groups (n = 6) given basal diet supplemented with 0 (Ni0), 5 (Ni5), 7.5 (Ni7.5) and 10 (Ni10) ppm Ni/kg of DM. Nickel was supplemented in the form of nickel sulphate hexahydrate (NiSO₄.6 H₂O) solution. To ensure the intake of the required amount of nickel by each animal, the calculated quantity of solution was mixed with 250 g concentrate mixture and offered individually to the calves. The calves were fed total mixed ration (TMR) consisting of green fodder, wheat straw and concentrate mixture in the ratio of 40:20:40 and the nutritional requirements were met according to NRC (2001) guidelines. Growth performance was recorded at fortnightly interval whereas, plasma minerals, haematology, antioxidant and immunity parameters were studied at monthly interval during the 150-day experimental period. Nutrient utilization and mineral balances were estimated with the help of a metabolism trial conducted at the end of feeding trial.ResultsSupplementation of Ni exhibited no influence on dry matter intake (DMI), body weight, average daily gain (ADG) and nutrient digestibility of dairy calves. However, the absorption and balance of minerals such as Ni, Fe, Cu, Zn and their respective plasma concentration increased (P < 0.05) with Ni supplementation and highest values were observed in calves fed 10 mg Ni/kg DM. The red blood cell (RBC) count, haemoglobin (Hb) concentration, haematocrit (HCT) and activity of superoxide dismutase (SOD) and catalase antioxidant enzymes showed highest increase (P < 0.05) in calves supplemented with Ni at level of 10 mg/kg DM as compared to other treatment groups. However, white blood cell (WBC) count, glutathione peroxidase (GPx), total antioxidant status (TAS), total immunoglobulins and IgG plasma concentration remained unaltered with addition of different levels of Ni in the diet of calves.ConclusionsThe supplementation of Ni at level of 10 mg/kg DM shows a positive effect on status of trace minerals such as Fe, Cu, Zn and improves the physiological conditions and health status of crossbred dairy calves indicated by improved haematology and antioxidant parameters.     

Effects of isobutyrate supplementation in pre- and post-weaned dairy calves diet on growth performance,rumen development,blood metabolites and hormone secretion

Isobutyrate supplements could improve rumen development by increasing ruminal fermentation products, especially butyrate, and then promote the growth performance of calves. The objective of this study was to evaluate the effects of isobutyrate supplementation on growth performance, rumen development, blood metabolites and hormone secretion in pre- and post-weaned dairy calves. In total, 56 Chinese Holstein male calves with 30 days of age and 72.9±1.43 kg of BW, blocked by days of age and BW, were assigned to four groups in a randomized block design. The treatments were as follows: control, low-isobutyrate, moderate-isobutyrate and high-isobutyrate with 0, 0.03, 0.06 and 0.09 g isobutyrate/kg BW per calf per day, respectively. Supplemental isobutyrate was hand-mixed into milk of pre-weaned calves and the concentrate portion of post-weaned calves. The study consisted of 10 days of an adaptation period and a 50-day sampling period. Calves were weaned at 60 days of age. Seven calves were chosen from each treatment at random and slaughtered at 45 and 90 days of age. BW, dry matter (DM) intake and stomach weight were measured, samples of ruminal tissues and blood were determined. For pre- and post-weaned calves, DM intake and average daily gain increased linearly (P<0.05), but feed conversion ratio decreased linearly (P<0.05) with increasing isobutyrate supplementation. Total stomach weight and the ratio of rumen weight to total stomach weight tended to increase (P=0.073) for pre-weaned calves and increased linearly (P=0.021) for post-weaned calves, whereas the ratio of abomasum weight to total stomach weight was not affected for pre-weaned calves and decreased linearly (P<0.05) for post-weaned calves with increasing isobutyrate supplementation. Both length and width of rumen papillae tended to increase linearly for pre-weaned calves, but increased linearly (P<0.05) for post-weaned calves with increasing isobutyrate supplementation. The relative expression of messenger RNA for growth hormone (GH) receptor and 3-hydroxy-3-methylglutaryl-CoA synthase 1 in rumen mucosa increased linearly (P<0.05) for pre- and post-weaned calves with increasing isobutyrate supplementation. Blood concentrations of glucose, acetoacetate, β-hydroxybutyrate, GH and IGF-1 increased linearly (P<0.05) for pre- and post-weaned calves, whereas blood concentration of insulin decreased linearly with increasing isobutyrate supplementation. The present results indicated that isobutyrate promoted growth of calves by improving rumen development and its ketogenesis in a dose-dependent manner.     

Chemerin induces lipolysis through ERK1/2 pathway in intramuscular mature adipocytes of dairy bull calves

The adipokine Chemerin has been reported to regulate differentiation and metabolism of adipocytes, but the mechanism underlying lipolysis is still largely unknown. The purpose of this study was to explore whether ERK1/2 pathway is involved in regulating Chemerin during bovine intramuscular mature adipocyte lipolysis. Intramuscular mature adipocytes of dairy bull calves were cultured in vitro and were treated with Chemerin or U0126, which is an inhibitor of ERK1/2 pathway. The results showed that TG content in cells was significantly decreased, glycerol and free fatty acid were significantly increased in cell culture media, and the expression of phosphorylated ERK1/2 in cells was increased in Chemerin-treated group, suggested that ERK1/2 pathway was involved in regulation of lipolysis by Chemerin. In addition, the expression of lipolytic-related critical factors ATGL, HSL, LPL, PPARα, UCP3, and CPT1 were upregulated, but the expression of adipogenic key factors, including PPARγ and C/EBPα were downregulated by Chemerin. Interestingly, all the effects of Chemerin on genes expression in intramuscular mature adipocytes or fat tissue were inhibited by U0126, showed that the function of Chemerin to promote adipose decomposition will be significantly weakened if the ERK1/2 pathway is suppressed, and confirmed that ERK1/2 pathway is involved in mediate Chemerin-enhanced lipolysis. In conclusion, the study demonstrated that Chemerin induce intramuscular mature adipocytes lipolysis through activation of the ERK1/2 pathway. Our research at least provide partial mechanisms of Chemerin on lipolysis and deposition of intramuscular fat tissue of dairy bull calves.     

Analysis of pre-weaning feeding policies and other risk factors influencing growth rates in calves on 11 commercial dairy farms

Growth rates in pre-weaned calves influence their health, age at first calving and lifetime productivity. Many farms restrict milk rations to encourage solid feed intake and facilitate early weaning, but this can compromise growth. This study determined the milk feeding policies and associated growth rates on 11 commercial dairy farms in South East England, each following their normal management regime. Between 26 and 54 heifers were recruited per farm, providing a final cohort of 492, of which 71% were pure Holstein. Information on calf rearing practices (feeding, weaning, housing) and health was collected via questionnaires and weekly observations. Estimates of actual milk fed (kg solids) between 1 and 63 days were calculated for individual calves. Morphometric data (weight, height, length) were taken at weeks 1, 5 and 9 and at a median age of 7.5 months and growth rates were calculated. Most calves were fed milk replacer via automated feeders (four farms), teat feeder (one) or buckets (four) whereas two farms provided drums of acidified waste milk. Farms fed between 4 and 6 l/day of milk at mixing rates of 10% to 15%, providing 400 to 900 g/day of milk solids. Both skeletal growth rates and average daily weight gain (ADG) increased in the second month of life compared with the first: height growth from 0.17±0.14 to 0.25±0.16 cm/day and ADG from 0.48±0.25 to 0.71±0.28 kg/day. Post-weaning heifers up to 7.5 months had height increases of 0.16±0.035 cm/day and ADG of 0.83±0.16 kg/day. From 1 to 63 days 70% of calves had growth rates <0.7 kg/day and of these 19.6% gained <0.5 kg/day. Mean ADG before 9 weeks varied between farms from 0.52±0.30 to 0.75±0.20 kg/day. This was related to the amount of milk fed at both a farm and individual calf level. Increasing the total milk solids fed between 1 and 63 days from 20.4 to 46.3 kg (the 10^th to 90^th percentile observed) was associated with an increase of 0.11 kg/day ADG. All farms had a wide variation in growth rates despite single feeding policies. Higher circulating immunoglobulin G and IGF1 concentrations were associated with better growth, whereas low temperatures in month of birth, high scores for diarrhoea, respiratory and umbilical disease and large birth size reduced growth. Many commercially grown dairy heifers therefore experienced growth restriction in the pre-weaned period, potentially reducing their health, welfare and productivity.     

Effect of pre-slaughter handling,exercise and the presence of a dog on lamb welfare and meat quality

Before slaughter, lambs may experience several stressors such as feed and water deprivation, handling and transport that have the potential to negatively impact welfare and meat quality. The objective of this study was to evaluate the effect of pre-slaughter handling, exercise and the presence of a dog on the behaviour and physiology of lambs and meat quality at slaughter. At 6 months of age, 60 lambs (n=20 lambs/replicate; three replicates) were allocated to one of the two treatment groups (n=30 lambs/treatment): low (LOW) intensive handling or high (HIGH) intensive handling. LOW lambs were moved short distances, quietly and without the use of a dog before transport. HIGH lambs were moved quickly, long distances and with a dog present before transport. Lamb behaviour (standing, lying, rumination and panting) was recorded for 1 h before (post-treatment) and after transport (post-transport), and for 30 min before slaughter (pre-slaughter). Blood samples were collected before (baseline), after transport (post-transport) and at exsanguination (at slaughter) to assess cortisol, lactate and non-esterified fatty acid (NEFA) concentrations. At slaughter, lamb carcases (M. longissimus lumborum) were evaluated for pH levels, drip and cook loss, and tenderness. HIGH lambs spent more time standing (P<0.001) and panting (P<0.001) and less time lying (P<0.001) and ruminating (P<0.001) post-treatment than LOW lambs, but more (P<0.001) time ruminating post-transport. All lambs spent more time standing (P<0.001) and less time lying (P<0.001) and panting (P<0.001) post-transport and pre-slaughter than post-treatment. Cortisol concentrations were greater (P<0.001) in lambs post-transport and at slaughter compared with baseline values. Lactate concentrations were lower (P=0.002) in HIGH than LOW lambs. In addition, NEFA concentrations were higher (P<0.001) post-transport and at slaughter in HIGH compared with LOW lambs. Ultimate pH was higher (P<0.001) in HIGH than LOW lambs and pH declined quicker (P=0.012) in LOW than HIGH lambs. Cook loss, drip loss and shear force were lower (P⩽0.05) in HIGH than LOW lambs. The HIGH intensive pre-slaughter handling regime used in the present study caused stress in lambs and increased ultimate pH that could potentially negatively impact welfare, product quality and consistency.     

Effect of switch trimming on udder and teat hygiene of dairy cows

The study objective was to determine the effects of trimming the switch of dairy cows on teat-end bacterial counts and udder hygiene scores. Cows (n = 102) were blocked by days in milk, milk production, and parity and then assigned to (a) treatment (trimming of their tail switch using a commercially available trimmer), or (b) control (unaltered tails). Udder hygiene was recorded for cows on Days 0 (initiation of treatment), 32, and 64. A subset of cows (n = 21) was used to assess Streptococci and coliform bacterial populations on teat ends. Samples were collected by swabbing the left front teat end before milking on Days 0, 32, and 64 and were cultured within 24 hr of sampling. The GLIMMIX and PROC Frequency (SAS Version 9.3) were used to analyze data. There were no treatment effects of switch trimming on hygiene scores or bacterial counts. These findings suggest that udder hygiene may not be driven by tail status. Environmental and management factors, such as cleanliness, stall bedding, and stall design, may be more important contributing factors in maintaining udder health.     

Reactions of calves to handling depend on housing condition and previous experience with humans

This study investigated the influence of stockperson's behaviour and housing conditions on calves' behavioural reactions to people, and behavioural and physiological reactions to handling and short transport. Sixty-four Finnish Ayrshire male calves were used; half of them were housed in individual pens, the other half were housed in group pens of two calves. In both housing conditions half of the calves received minimal contact from the stockperson, while the other half were stroked on their necks and shoulders for 90s a day, after milk meals. The effects of housing and contact with the stockperson on the responses of calves to people, either entering or approaching the pen, were studied. Furthermore, calves' behavioural and physiological (cortisol, heart rate) reactions to being loaded onto a truck, transported for 30min and unloaded were observed. When a person entered the home pen, calves housed by pairs took significantly more time to interact and interacted less frequently with the person than individually housed calves did (p<0.01). Calves that received additional contact interacted for longer time with the unfamiliar person than calves with minimal contact (p=0.02). When a person approached the front of the calves' pens, less withdrawal responses were shown by calves that had received additional contact (p<0.05) than those that had received minimal contact. When the calves were loaded onto the truck, it took more time and effort to load pair housed calves than individually housed calves (p<0.01) and less effort to load calves that had received additional contact (p<0.01) compared to those that had received minimal contact. During loading additional contact calves had lower heart rates (p<0.05) than those that had received minimal contact, while during transport pair housed calves had lower heart rates compared to individually housed ones (p<0.05). For all the observations performed, no interactions were found between housing conditions and human contact.It is concluded that, compared to calves housed individually, calves housed in pairs are less ready to approach humans and less easy to handle. Providing calves with regular positive contacts makes them less fearful of people and improves handling. Due to the greater difficulty in handling calves housed in groups, it is concluded that these animals need to have regular contact with humans.     

IgG1 variations in the colostrum of Holstein dairy cows

High-immune quality colostrum (IgG1 concentration ⩾50 g/l) is crucial for the health and development of the young calf. Studies on colostrum quality tend to focus on external factors such as breed, parity or dry period length, but few have focused on within-cow variations. Here we ran experiments to gain a deeper insight into within-cow variation in IgG1 concentrations in dairy cow colostrum. Trials were performed in an experimental farm, located in the Western part of France. Colostrum from each quarter and a composite sample (mix of four quarters) were concomitantly collected on 77 Holstein dairy cows just after calving to assess the influence of sample type on IgG1 concentrations. Variation in IgG1 concentrations during the first milking was studied on samples from nine cows collected every minute from the start of milking. Repeatability of colostral IgG1 concentration was estimated from 2009 and 2010 data on 16 healthy cows. IgG1 concentrations were tested using a radial immunodiffusion method. Sensitivity and specificity were similar regardless of sample type tested (individual quarter or composite milk). Mean average IgG1 concentration was 54.1 g/l in composite colostrum, and was significantly higher in hind quarter teats (56.2 g/l) than front quarter teats (53.1 g/l). Average IgG1 concentration did not change significantly during colostrum milking, and the variations observed (15% or less) were likely due to the laboratory method (CV 15%). IgG1 concentrations in dam colostrum increased slightly from 2009 to 2010 due to BW and parity effects. In 56% of cases, colostrum quality could have been assessed on either individual or composite colostrum samples collected at any time during the first milking without affecting the reliability of the measurement. However, in other cases, differences were significant enough to mean that estimates of average IgG1 concentration in colostrum from any one quarter would not be reliable. It is concluded that colostrum quality, from an IgG1 concentration point of view, could be assessed with a composite sample taken at any time during the first milking.     

Physiologic responses of dairy calves to environmental heat stress

The effects of thermal stress were identified in terms of a calf's systemic response. The following physiological parameters were monitored during successive exposure of eight Holstein calves to five temperature levels ranging from 15.5°C to 37.7°C at 60% RH: stroke volume, heart rate, arterial systolic and diastolic pressures, plasma cortisol and thyroxine levels, and internal and skin temperatures. Results indicated that 3 to 4- week-old male calves respond to acute heat stress only above 32.2°C at 60% RH and do not demonstrate a marked attempt to acclimate until at least four to five hours of exposure at 37.7°C.     

Effect of grazing on the cow welfare of dairy herds evaluated by a multidimensional welfare index

Structural development in the prime sector has led to increasing herd sizes and new barn systems, followed by less summer grazing for dairy cows in Denmark. Effects of grazing on single welfare measures in dairy cows – for example, the presence of integument alterations or mortality – have been studied under different conditions. However, the effect of grazing on welfare, conceptualised as the multidimensional physical and mental state of the animal, has not yet been studied in contemporary cubicle loose-housing systems. The aim of our study was to investigate, based on a Welfare Quality® inspired multidimensional dairy cow welfare assessment protocol, the within-herd effect of summer grazing compared with winter barn housing in Danish dairy herds with cubicle free-stall systems for the lactating cows. Our hypothesis was that cow welfare in dairy herds was better during summer grazing than during full-time winter housing. Furthermore, we expected improved welfare with an increase in daily summer grazing hours. In total, 41 herds have been visited once in the winter and once in the summer of 2010 to assess their welfare status with 17 different animal- and resource-based welfare measures. A panel of 20 experts on cattle welfare and husbandry evaluated the relative weight of the 17 welfare measures in a multidimensional assessment scheme. They estimated exact weights for a priori constituted severe compared with moderate scores of welfare impairment concerning each measure, as well as relevance of the measures in relation to each other. A welfare index (WI; possible range 0 to 5400) was calculated for each herd and season with a higher index indicating poorer welfare. The within-herd comparison of summer grazing v. winter housing considered all the 17 measures. The mean WI in summer was significantly lower (better) than in winter (mean 2926 v. 3330; paired t-test P = 0.0001) based on a better state of the integument, claw conformation and better access to water and food. Body condition and faeces consistence were worse in summer. Many daily grazing hours (range average above 3 to 9 h) turned out to be more beneficial than few daily grazing hours (range average above 9 to 21 h) for the welfare of the dairy herds. In conclusion, this study reports a positive within-herd effect of summer grazing on dairy cow welfare, where many daily grazing hours were more beneficial than few daily grazing hours.     

Questionnaire identifying management practices surrounding calving on spring-calving dairy farms and their associations with herd size and herd expansion

Healthy calves are fundamental to any profitable dairy enterprise. Research to-date, has focused on year-round calving systems which experience many different challenges compared to spring-calving systems. The objective of the present study was to determine the on-farm dry cow, calving, and colostrum management practices of spring-calving dairy production systems, and quantify their associations with herd size and herd expansion status (i.e. expanding or not expanding). Information on these management practices was available from a survey of 262 Irish spring-calving dairy farmers, representative of the Irish national population. Herd expansion in the 2 years before, and the year that the survey was conducted was not associated with any of the management practices investigated. Fifty-three percent of respondents had an average calving season length of 10 to14 weeks with 35% of herds having a longer calving season. Previous research in cattle has documented that both colostrum source and feeding management are associated with the transmission of infectious disease from cow to calf. In the present study 60% of respondents fed calves colostrum from their own dam; however, 66% of those respondents allowed the calf to suckle the dam, 23% of survey respondents fed calves pooled colostrum. Larger herds were more likely (P<0.01) to use pooled colostrum supplies, while smaller herds were more likely (P<0.05) to allow the calf to suckle the dam. The majority (86%) of respondents had stored supplies of colostrum; average-sized herds had the greatest likelihood of storing colostrum (P<0.05), compared to other herd sizes; larger sized herds had a lesser likelihood (P<0.05) of storing colostrum in a freezer, compared to other herd sizes. Although freezing colostrum was the most common method used to store colostrum (54% of respondents), 17% of respondents stored colostrum at room temperature, 29% of which stored it at room temperature for greater than 4 days. The results from the present study indicate that a particular focus needs to be placed on calving and colostrum management because this study has highlighted a number of areas which are below international standards, and may have repercussions for calf health. Furthermore, management practices on larger farms could be improved and, as these represent the future of dairy farming, a focus needs to be placed on them. Expanding herds are not a particular concern as herd expansion, independent of herd size, does not seem to be associated with calving and colostrum management practices on Irish spring-calving dairy herds.     

Evaluation of nutrition models to estimate performance of young dairy calves: a meta-analytical study under tropical conditions

Mathematical models are important tools to estimate nutritional requirements and animal growth. Very few calf models generated from other countries with different feeding programs, environment and production systems have been evaluated. The objective of this paper is to evaluate two calf models: (i) the National Research Council (NRC) in 2001 and (ii) the updates published by Van Amburgh and Drackley in 2005 and inputted into Agricultural Modeling and Training Systems (AMTS, version 3.5.8). Data from 16 previous studies involving 51 diets for dairy calves under tropical conditions (n=485 calves, initial BW 37.5±4.35 kg and weaning weight of 62.0±10.16 kg) were used. The calves were fed with whole milk, milk replacer or fermented colostrum, plus starter (20.9±1.78% of CP). The accuracy of the average daily gain (ADG) prediction was evaluated by mean bias, mean square prediction error (MSPE), concordance correlation coefficient, bias correction factor (Cb), and regression between the observed and predicted values. The ADG observed from birth to weaning was 0.452±0.121 kg/day. Calves fed with whole milk had greater ADG compared with calves fed milk replacer (0.477 v. 0.379 kg/day) during the milk-feeding period. When all data were pooled (n=51 diets), predictions had a mean bias of −0.019 and 0.068 kg/day for energy-allowable gain using NRC and AMTS models, respectively. The regression equation between observed and predicted values obtained from energy of diets showed an intercept different from zero (P<0.0001) and slope that differed from unity (P<0.0001). In a second evaluation, when calves were fed only milk replacer, the energy-allowable gain from AMTS showed the lowest mean bias (0.008 kg/day) and 82.1% of the MSPE value originated from random errors. The lowest MSPE, the higher Cb value and no significant slope bias (P>0.05) indicate that the AMTS growth model resulted in accurate predictions for calves fed with milk replacer. However, within these latter two approaches, the goodness of fit (R²) was low, representing low precision. The weight gain estimated by the energy available from the diet was overestimated by 19 g/day when calculated by the NRC and underestimated by 68 g/day when calculated by AMTS. The reasons for this discrepancy need to be understood, for only then new models could be developed and parameterized to estimate animal performance in tropical conditions more accurately and precisely.