Development of Ox-Coyote Cycle of Sarcocystis cruzi1

The ox-coyote cycle of Sarcocystis cruzi was studied by killing 38 calves between 4 and 153 days postinoculation (DPI) with 55 × 10³-5 × 10⁸ sporocysts from the intestines of coyotes. At 4 DPI, a zoite was found within the lumen of a mesenteric lymph node artery. At 7 DPI, zoites were found in mononuclear cells and in endothelial cells in mesenteric arteries. First generation meronts (41.0 × 17.5 μm in diameter) occurred 7–26 DPI in mesenteric lymph nodes. At 19–46 DPI, second generation meronts occurred in kidneys, muscles, and other tissues: renal meronts were 19.6 × 11.0 μm, and intramuscular meronts were 25.0 × 11.1 μm. Merozoites were found in the peripheral blood 17 DPI and later at 24–46 DPI. They divided by endodyogeny in mononuclear cells. Sarcocysts were seen first in the heart at 45 DPI and contained one or two metrocytes. At 55 DPI, sarcocysts containing only metrocytes were found in striated muscles, heart, and in smooth muscles of the urinary bladder, rumen, omasum, abomasum, and small intestine. At 67, 87, 112, and 153 DPI, sarcocysts were found only in striated muscles and in the heart. At 67 DPI, sarcocysts were up to 360 μm long. They contained only metrocytes and were not infective to the dog. At 86 DPI, sarcocysts contained mostly bradyzoites, a few metrocytes, and were infective to a coyote. The thin-walled sarcocysts grew to a maximum length of 800 μm and contained bradyzoites that were 10.9 × 3.0 μm. At 90 DPI, two mature sarcocysts were found in 2 of 73 sections of brain and spinal cord; hundreds of sarcocysts were present in sections of tongue and heart of this calf. Gametogony occurred in the small intestine of the coyote. Macro-and microgamonts were found in goblet cells of the small intestines of coyotes 6 h after the ingestion of infected meat. Microgamonts were few and contained 3–11 slender gametes. Oocysts were seen at 12 h and sporulation was completed 9 DPI. The prepatent period in the coyote was 8 days. The ox-coyote cycle is compared with ox-dog cycle.     

Abortion and Calf Mortality in Danish Cattle Herds

The aetiology of abortions and calf mortality in 65 Danish cattle herds consisting of both dairy and beef breeds during a 1-year period is described. All observed aborted foetuses, stillborn calves, and calves dying before 6 months of age were necropsied, and relevant microbiological examinations were performed. A total of 240 calves and 66 abortions were submitted corresponding to a calf mortality rate of 7%. The abortion frequency could not be calculated. 43% of the calves died at day 0, while 22% were aborted, 15% died during the first week of life, 9% died from 1 to 4 weeks of age, and 11% died at the age of 1 to 6 months. The most common cause was neonatal pulmonic atelectasis (stillbirth) followed by foetal infections, pneumonia, and septicaemia.     

Development and ultrastructure of first-generation meronts of Sarcocystis cruzi in calves fed sporocysts from coyote feces

The development of Sarcocystis cruzi Hasselmann (syn. S. fusiformis Railliet) meronts was studied in seven 7- to 10-day-old calves filled 4, 7, 11, 15, 22, 25 and 28 days postinoculation (DPI) with 5 x 10(7) sporocysts from feces of coyotes. No meronts were found 4 and 7 DPI. Young and intermediate meronts with 1-16 nuclei were found in endothelial cells of arteries in mesenteric lymph nodes, but not in kidneys 11 DPI. Mature meronts were noted in endothelial cells of arteries, arterioles, or capillaries of many organs of calves killed 15 to 25 DPI. No first-generation meronts were found 28 DPI. By electron microscopy, all stages of the first-generation merogony were found free within the host cell cytoplasm and not within a parasitophorous vacuole. The appearance of intranuclear spindles preceded the formation of merozoites by endopolygeny. Mature meronts measured 41.0 x 17.5 (34-50 x 15-24) microgram, contained approximately 100-350 merozoites, and had 2 to 4 relatively small residual bodies, 2.8 microgram in diameter. Merozoites measured 6.3 x 1.5 (5.5-7 x 1 microgram) and contained most of the organelles characteristically found in coccidian merozoites. Micropores were observed in merozoites, but not in young and intermediate meronts. Merozoites were seen free in the lumen of blood vessels, in intracellular areas, and free within the host cell cytoplasm.     

Shedding of Escherichia coli O157:H7 in dairy cattle housed in a confined environment following waterborne inoculation

A study of Escherichia coli O157:H7 transmission and shedding was conducted with bull calves housed in individual pens within a confined environment. For comparative purposes, the numbers and duration of E. coli O157:H7 shedding in naturally infected calves were monitored after a single purchased calf (calf 156) tested positive prior to inoculation. During the next 8 days, the calves in adjacent pens and a pen directly across a walkway from calf 156 began to shed this serotype O157:H7 strain. Five of the eight calves in this room shed this O157:H7 strain at some time during the following 8 weeks. The numbers of E. coli O157:H7 isolates shed in these calves varied from 60 to 10(5) CFU/g of feces, and the duration of shedding ranged from 17 to >31 days. The genomic DNAs from isolates recovered from these calves were indistinguishable when compared by using XbaI digestion and pulsed-field gel electrophoresis. Inoculation of calves with 1 liter of water containing ca. 10(3) to 10(4) CFU of E. coli O157:H7/ml resulted in shedding in 10 of 12 calves (trial 1, 4 of 4 calves; trial 2, 6 of 8 calves). The inoculated calves shed the inoculation strain (FRIK 1275) as early as 24 h after administration. The duration of shedding varied from 18 to >43 days at levels from 10(2) to 10(6) CFU/g of feces. The numbers of doses necessary to initiate shedding varied among calves, and two calves in trial 2 never shed FRIK 1275 after four doses (ca. 10(6) CFU per dose). Results from this study confirm previous reports of animal-to-animal and waterborne dissemination of E. coli O157:H7 and highlight the need for an effective water treatment to reduce the spread of this pathogen in cattle.     

Development and Ultrastructure of First-Generation Meronts of Sarcocystis cruzi in Calves Fed Sporocysts from Coyote Feces*

SYNOPSIS. The development of Sarcocystis cruzi Hasselmann (syn. S. fusiformis Railliet) meronts was studied in seven 7- to 10-day-old calves killed 4, 7, 11, 15, 22, 25 and 28 days postinoculation (DPI) with 5 × 10⁷ sporocysts from feces of coyotes. No meronts were found 4 and 7 DPI. Young and intermediate meronts with 1–16 nuclei were found in endothelial cells of arteries in mesenteric lymph nodes, but not in kidneys 11 DPI. Mature meronts were noted in endothelial cells of arteries, arterioles, or capillaries of many organs of calves killed 15 to 25 DPI. No first-generation meronts were found 28 DPI. By electron microscopy, all stages of the first-generation merogony were found free within the host cell cytoplasm and not within a parasitophorous vacuole. The appearance of intranuclear spindles preceded the formation of merozoites by endopolygeny. Mature meronts measured 41.0 × 17.5 (34–50 × 15–24) μm, contained ～ 100–350 merozoites, and had 2 to 4 relatively small residual bodies, 2.8 μm in diameter. Merozoites measured 6.3 × 1.5 (5.5–7 × 1 μm) and contained most of the organelles characteristically found in coccidian merozoites. Micropores were observed in merozoites, but not in young and intermediate meronts. Merozoites were seen free in the lumen of blood vessels, in intracellular areas, and free within the host cell cytoplasm.     

Performance of calves on diets containing Amaranthus leaf meal

Experiments were conducted to compare leaf meal of Amaranthus hy bridus sub-species hy bridus (Green Head) with lucerne meal and to study the effect of including up to 40% leaf meal of the same species of Amaranthus in calf rations. Fourteen concentrate diets calculated to be iso-caloric (75% TDN) and iso-nitrogenous (18% CP) were each given ad libitum to four Friesian calves from Day 11 to Day 56 post partum. Whole milk was also given at the rate of 4 l per calf per day. The first seven diets (Experiment I) contained 0, 5, 10 and 15% of either Amaranthus meal or lucerne meal. The rest (Experiment II) contained 0, 10, 20, 25, 30, 35 and 40% of Amaranthus leaf meal.Liveweight gains were similar on all the diets within each experiment and averaged about 0.5 and 0.4 kg/day in Experiments I and II, respectively. This was attributed to identical nutrient intake and efficiency of feed utilization. The relationship between oxalate intake, its disappearance in the gastro-intestinal tract of the experimental calves and apparent dietary calcium availability did not cause any appreciable differences in the performance of the experimental calves. Blood calcium levels of all the calves were within the normal range (9–12 mg/100 ml) during both trials.It is concluded that Amaranthus leaf meal is of comparable feeding value to lucerne meal in calf early weaner diets and that dairy calves perform well when given diets containing up to 40% leaf meal of Amaranthus.     

Preparturient changes in plasma concentrations of estrone,estradiol-17β and estradiol-17α in the fetal calf: Effects of dexamethasone infusion

The concentrations of total estrogens in fetal calf plasma were determined during a 6–10 day period immediately before delivery. Comparison was made between levels found in untreated calves and calves infused with dexamethasone at the rate of 0.1, 1.0 and 10 mg/24 hours. In untreated calves the plasma estrone, estradiol-17β and estradiol-17α levels remained relatively constant at 38 ± 7 ng ml^?1 (mean ± SEM n = 3), 46 ± 6 ng ml^?1 and 29 ± 5 ng ml^?1 respectively. Infusion with dexamethasone at 0.1 mg/24 hr (3 calves) and 1.0 mg/24 hr (3 calves) was without dramatic effect on plasma estrogen levels. However, in one fetus infused with 10.0 mg/24 hr the dexamethasone treatment may have caused a transitory rise in the levels of all estrogens examined.     

Ovarian function and pregnancy rates in reindeer calves (Rangifer tarandus ) in Southern Norway

Reindeer calves (n = 632) were slaughtered in November/December (n = 476) or in January (n = 156). Dressed weights and amount of perirenal fat were recorded, and the reproductive organs were collected. A separate group of 130 reindeer calves were weighed at 7 months of age and were followed up with repeated weighings and pregnancy examinations up to 21 months. The onset of puberty and the pregnancy rate were significantly influenced by body weight and the amount of perirenal fat. Approximately 60 g of perirenal fat and 22 kg dressed weight were found at the lower limits for pregnancy. A total of 222 (35%) animals had reached puberty and 126 (20%) were pregnant when examined after slaughter. Animals which conceived during their first autumn showed only a moderate weight gain the following year, and the calf mortality rate in these animals was 47.4%. It was concluded that calf pregnancies are common among the reindeer of Southern Norway and that measures need to be taken to prevent them.     

Bull selection and use in northern Australia. 4. Calf output and predictors of fertility of bulls in multiple-sire herds

On 10 northern Australian properties, the number of calves sired (calf output) by individual bulls in multiple-sire matings was measured by DNA typing for paternity. There were 235 bulls (92 Santa Gertrudis, 25 5/8 Brahman and 119 Brahman) from 37 multiple-sire mating groups. Number of bulls in groups ranged from 2 to 25 and ages of bulls ranged from 2 to 5 years. Mating periods were for 3-12 months and bull mating percentages were 2.5-6%. In all, there were 4251 calves tested and the resolution of paternity ranged from 92.5 to 100% and averaged 97.7% across all sites. This included 9.9% of calves with no potential sires in any of the mating groups. Of the 235 bulls mated, 58% sired 10% or less calves in each of their respective mating groups with 6% not siring any calves. In contrast, 14% sired over 30% of the calves in each of the respective mating groups. When bulls were mated in groups of 8-24, the maximum percent of calves sired by individual bulls was 26+/-7% (mean+/-S.D.) with a range 11-36%. However, when bulls were mated in groups of 2-7, the maximum percent of calves sired by individual bulls was 59+/-19% with a range 24-94%. Calf output of bulls was moderately repeatable across years at four of five sites. Multiple regression models relating pre-mating measures of physical, seminal and behavioural traits to calf output were developed for the three breed groups. In all, only 138 of the 235 bulls were included in the models (40 Santa Gertrudis, 24 5/8 Brahman and 74 Brahman). Sheath and testicular traits, such as scrotal circumference and testicular tone, were generally not related to calf output, the exceptions being sheath depth in Brahman bulls which was negatively related (P<0.05) and scrotal circumference in 5/8 Brahmans which was positively related (P=0.08) to calf output. Dominance was only included in the 5/8 Brahman model but there was no significant relationship between dominance hierarchy and calf output. Semen motility was only related (P<0.05) to calf output in 5/8 Brahmans. However, measures of semen quality based on spermatozoa morphology were important contributors to calf output in the Santa Gertrudis and Brahman models where percent normal spermatozoa was positively related (P<0.01) to calf output. In Santa Gertrudis and Brahman bulls, measures of sexual behaviour in the serving capacity test were related to calf output. In Santa Gertrudis, these were for the number of displays of sexual interest (P<0.05), and mounts (P<0.01), but not number of serves, whilst in Brahman bulls, libido score was positively related to calf output (P<0.05). The models only explained 35-57% of the variation in calf output.     

Experimental infection of calves and adult cattle with Escherichia coli O157:H7.

Preweaned calves and adult cattle were inoculated with 10(10) CFU of Escherichia coli O157:H7 strain 3081, a calf isolate which produces Shiga-like toxin, to define the magnitude and duration of fecal shedding of E. coli O157:H7 for each age group. Fecal samples of eight of eight, eight of eight, three of eight, and two of eight calves were positive at 2, 7, 14, and 20 weeks, respectively. In contrast, nine of nine, two of nine, and one of nine steers were positive at 2, 7, and 14 weeks, respectively. The magnitude of shedding (CFU per gram) by individual animals at any one time postinoculation varied widely within each age group but was greater for calves as a group. The differences in shedding patterns between adults and calves were statistically significant. After inoculation, 25 of 29 animals remained healthy and 4 of 17 calves had transient diarrhea. Histologic sections of the brain, kidney, jejunum, ileum, cecum, and colon taken at necropsy from nine calves either 3, 14, or 18 days postinoculation or three adults either 2, 3, or 4 days postinoculation were normal. E. coli O157:H7 was recovered from the alimentary tracts of all of the animals necropsied, and there was no evidence of spread to the liver, spleen, or kidneys. Four calves that had ceased shedding were reinfected when inoculated again with the same strain. E. coli O157:H7 was recovered from none of five and two of five adults inoculated with 10(4) and 10(7) CFU, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Endocrine Profiles, Haematology and Pregnancy Outcomes of Late Pregnant Holstein Dairy Heifers Sired by Bulls Giving a High or Low Incidence of Stillbirth

The high incidence of stillbirth in Swedish Holstein heifers has increased continuously during the last 15 years to an average of 11% today. The pathological reasons behind the increased incidence of stillbirth are unknown. The present experiment was undertaken to investigate possible causes of stillbirth and to study possible physiological markers for predicting stillbirth. Twenty Swedish Holstein dairy heifers sired by bulls with breeding values for a high risk of stillbirth (n = 12) (experimental group) and a low risk of stillbirth (n = 8) (control group, group B) were selected based on information in the Swedish AI-data base. The experimental group consisted of 2 subgroups of heifers (groups A1 and A2) inseminated with 2 different bulls with 3.5% and 9% higher stillbirth rates than the average, and the control group consisted of heifers pregnant with 5 different bulls with 0%–6% lower stillbirth rates than the average. The bull used for group A1 had also calving difficulties due to large calves as compared to the bull in group A2 showing no calving difficulties. The heifers were supervised from 6–7 months of pregnancy up to birth, and the pregnancies and parturitions were compared between groups regarding hormonal levels, haematology, placental characteristics and calf viability. In group A1, 1 stillborn, 1 weak and 4 normal calves were recorded. In group A2, 2 stillborn and 4 normal calves were registered. All animals in the control group gave birth to a normal living calf without any assistance. The weak calf showed deviating profiles of body temperature, saturated oxygen and heart rates, compared with the normal living calves. No differences of the placentome thickness, measured in vivo by ultrasonography were seen between the groups. The number of leukocytes and differential cell counts in groups A1 and A2 followed the profiles found in the control group. In group A1, a slight decrease of oestrone sulphate (E1SO4) levels was found in the animal delivering a stillborn calf from the first 24-h blood sampling at 6 weeks to the second at 3 weeks prior to delivery, while the levels of E1SO4 at both periods in the animal delivering a weak calf followed the profile in animals delivering a normal living calf. During late pregnancy and at the time of parturition, the levels of E1SO4 and PAGs in animals delivering a stillborn or weak calf (from group A1) followed the normal profiles found in animals delivering a normal living calf. In group A2, low levels of E1SO4 and pregnancy associated glycoproteins (PAGs) over 24 h at both 3 and 6 weeks prior to parturition (<1.5 nmol/L) were recorded in animals delivering a stillborn calf. During late pregnancy and parturition, the levels of E1SO4 and PAGs were slightly lower during 30–50 days prior to delivery and increased with a lower magnitude at the time of parturition. In conclusion, our results indicate that the aetiology behind stillbirth varies depending on the AI-bulls used and is associated with dystocia or low viability of the calves. Deviating profiles of oestrone sulphate (E1SO4) and pregnancy associated glycoproteins (PAGs) in animals delivering a stillborn calf not caused by dystocia were observed, suggesting placental dysfunction as a possible factor. The finding suggests that the analyses of E1SO4 and PAGs could be used for monitoring foetal well-being in animals with a high risk of stillbirth at term.     

UNOBSERVED KILL OF NURSING DOLPHIN CALVES IN A TUNA PURSE-SEINE FISHERY

The kill of dolphins ( Stenella attenuata and S. longirostris ) in the eastern tropical Pacific tuna purse-seine fishery has been underestimated because of unobserved deaths of nursing calves due to separation from their mothers during fishing. Based on an analysis of dolphins killed from 1973 to 1990, and depending on the length at which calves are assumed to become independent, there was a deficit of calves relative to the number of lactating females killed in 24%–32% of 1,847 spotted-dolphin sets and in 13%–19% of 563 spinner-dolphin sets. We found a deficit of 0.31–0.45 spotted dolphin and 0.15–0.26 spinner dolphin calves per set. If these missing calves were added to the observed kill, it would represent an increase in the kill of 10%–15% for spotted dolphins and 6%–10% for spinner dolphins in the sets we examined. We did not attempt to estimate the actual number of unobserved calf deaths due to purse-seine fishing on dolphins, either in the sets we examined or in all dolphin sets. The actual number of unobserved calf deaths is likely to be higher than the calf deficit we found. Separation of dolphin mothers from calves could occur at any of several points in the fishing process, but most of these would be invisible to us and not produce a calf deficit. Estimation of the actual number of unobserved calf deaths would require further information on how frequently permanent mother-calf separations occur, the fraction of calves that survive after separation, the fraction of lactating females set upon that are carrying calves, and the fraction of calves killed that are actually related to lactating females killed in the same set. In any case, the observation of a calf deficit indicates that the reported dolphin kill fails to measure the full impact of purse-seine fishing on spotted and spinner dolphin populations.     

Effects of early separation on the dairy cow and calf: 2. Separation at 1 day and 2 weeks after birth

This study investigated the effects of separating dairy calves from their mothers at 1 day (early separation) and 14 days (late separation) after birth. Behavioural observations were conducted on 24 Holstein dairy cow–calf pairs during the first 24 h after separation. Before separation, cow–calf pairs were generally inactive. After separation, cows from the late-separation treatment group showed higher rates of calling, movement and placing the head outside the pen, than cows in the early-separation group. Parity did not influence cow behaviour. During the first 2 weeks after calving, cows in the late-separation group (i.e. still with their calves) yielded less milk at milking, a difference at least partly due to the milk consumed by the calf. Milk yields from days 15–150 did not differ between the two groups. After separation, calves in the late-separation group moved and placed their heads outside the pen more often than early-separation calves. During the first 14 days after birth, late-separation calves gained weight at more than three times the rate of those separated early. When introduced to an unfamiliar calf at 6 weeks of age, calves from the late-separation group showed more intense social behaviour towards the unfamiliar calf than did those calves separated early. Thus, the response to separation by both cows and calves increased when calves were separated at 2 weeks rather than 1 day of age, but calves separated at the later age gained more weight and delayed separation appeared to influence the development of calf social behaviour.     

Shedding of Escherichia coli O157:H7 in Dairy Cattle Housed in a Confined Environment following Waterborne Inoculation

A study of Escherichia coli O157:H7 transmission and shedding was conducted with bull calves housed in individual pens within a confined environment. For comparative purposes, the numbers and duration of E. coli O157:H7 shedding in naturally infected calves were monitored after a single purchased calf (calf 156) tested positive prior to inoculation. During the next 8 days, the calves in adjacent pens and a pen directly across a walkway from calf 156 began to shed this serotype O157:H7 strain. Five of the eight calves in this room shed this O157:H7 strain at some time during the following 8 weeks. The numbers of E. coli O157:H7 isolates shed in these calves varied from 60 to 10⁵ CFU/g of feces, and the duration of shedding ranged from 17 to >31 days. The genomic DNAs from isolates recovered from these calves were indistinguishable when compared by using XbaI digestion and pulsed-field gel electrophoresis. Inoculation of calves with 1 liter of water containing ca. 10³ to 10⁴ CFU of E. coli O157:H7/ml resulted in shedding in 10 of 12 calves (trial 1, 4 of 4 calves; trial 2, 6 of 8 calves). The inoculated calves shed the inoculation strain (FRIK 1275) as early as 24 h after administration. The duration of shedding varied from 18 to >43 days at levels from 10² to 10⁶ CFU/g of feces. The numbers of doses necessary to initiate shedding varied among calves, and two calves in trial 2 never shed FRIK 1275 after four doses (ca. 10⁶ CFU per dose). Results from this study confirm previous reports of animal-to-animal and waterborne dissemination of E. coli O157:H7 and highlight the need for an effective water treatment to reduce the spread of this pathogen in cattle.     

Play behaviour in group-housed dairy calves, the effect of space allowance

In dairy calves kept in pens, lack of sufficient space may inhibit the performance of play behaviour. The present study investigated, firstly, if an increase in space allowance increases the occurrence of play behaviour, and secondly, if calves kept at a low space allowance perform more locomotor play when released individually in a large novel area. A total of 96 dairy calves in six repetitions were housed in groups of four, in pens of either 4, 3, 2.2 or 1.5 m(2) per calf from 2 weeks of age. The occurrence of play behaviour in the home environment was recorded continuously for each individual calf during 24 h at 5, 7 and 9 weeks of age. Locomotor play decreased over the weeks (54, 29 and 19 s for weeks 5, 7 and 9, respectively; F(2,40)=17.98; P<0.001), and the interaction between space allowance and week tended to be significant (F(6,40)=1.96; P<0.10). At 5 weeks of age, calves kept at 4 or 3 m(2) per calf performed more locomotor play in the home environment than calves at 2.2 or 1.5 m(2) per calf (68, 74, 38 and 39 s for 4, 3, 2.2 and 1.5 m(2) per calf, respectively; F(3,15)=3.40; P<0.05), but in weeks 7 and 9, no effects of space allowance were found. In addition, the duration of locomotor play was recorded for all calves during an individual 10-min open-field test in a 9.6x4.8 m arena at 4 and 10 weeks of age. During the open-field test at 10 weeks of age, calves from pens with 1.5 m(2) per calf performed more locomotor play than calves on the remaining treatments (10, 9, 12 and 25 s for 4, 3, 2.2 and 1.5 m(2) per calf, respectively; F(3,15)=4.05; P<0.05). The present study shows that an increase in the available space increases the occurrence of locomotor play in the home environment at 5 weeks of age. It also shows that calves kept in pens with the smallest space allowance performed more locomotor play behaviour when released in a large arena at 10 weeks of age.     

Reasons and risk factors for beef calf and youngstock on-farm mortality in extensive cow-calf herds

Raising calves and youngstock is an essential part of beef production. High on-farm mortality (unassisted death and euthanasia) is a consequence of poor animal health and welfare, and is economically unfavourable. The present study aimed to identify the reasons and risk factors for beef calf and youngstock on-farm mortality, using registry data for the years 2013 to 2015. Cox regression models were applied for the data of four age groups: calves up to 30 days (n=21 075), calves 1 to 5 months (n=21 116), youngstock 6 to 19 months (n=22 637) and youngstock ⩾20 months of age (n=9582). We found that dystocia, small birth weight and older parity of the mother increased the mortality hazard in calves up to 30 days of age. A summer birth was a common protective factor against mortality for calves up to 30 days and calves 1 to 5 months of age, compared with birth in other seasons. Among calves 1 to 5 months old, being the offspring of a first-parity cow was associated with significantly higher risk of death compared with calves who were the offspring of third- or higher-parity cows. A high herd-level stillbirth rate was associated with higher mortality hazard. The most commonly reported reasons for calf mortality were digestive disorders and respiratory disease. According to the models of youngstock from 6 months of age, male sex was a risk factor for mortality. Cattle having more than 10% dairy breed experienced a higher mortality risk in the ⩾20 months age group. No significant differences were found across regions, herd size or different breeds in any of the calf or youngstock groups. Metabolic and digestive disorders, as well as traumas and accidents, were the most common causes of mortality in beef youngstock older than 6 months. We can conclude that in young calves, animal-level factors associated with calving had a high impact on mortality. Further, timing calving for the warmer spring months would benefit calf survivability. Further studies including complementary information about farm factors adapted across the whole youngstock period is highly needed to provide sound recommendations in reducing on-farm mortality.     

Vertebral Fractures in Newborn Calves

A prospective study on vertebral fractures in newborn calves is described. Vertebral fractures were found in 7.0% of necropsied calves of the Danish Holstein-Friesian (SDM) and Red Danish Dairy (RDM) breeds. Cases were not found in submitted calves of the Jersey breed or beef breeds. At least in beef breeds this was probably due to the low number necropsied. The rate of vertebral fractures in SDM and RDM breeds and between males and females were similar. Most cases occurred in calves born by heifers, and manual traction force had been applied in all cases. All fractures which in most cases consisted of a simple epiphysiolysis were located at the thoraco-lumbar area, and especially the posterior epiphysis of T13 was afflicted.     

The effect of calf jacket usage on performance,behaviour and physiological responses of group-housed dairy calves

Poor performance and ill-health of calves in the pre-wean period can affect future productivity. Increasing numbers of producers are opting to use calf jackets as a means of mitigating the potential negative effects of low ambient temperatures, wind speed and precipitation on growth and health. This study aimed to use a range of noninvasive monitoring technologies to investigate the effects of using calf jackets in the first 3 weeks of life on calf performance and behavioural and physiological parameters. Ninety Holstein-Friesian calves were allocated to one of the two treatments: (i) Jacketed until 21 days of age and (J; n = 44) ii. Nonjacketed (NJ; n = 46). Calves were group housed and fed milk replacer (MR) and concentrate solid feed via automatic feeders. Calves were weaned at day 56, and the experiment was completed at day 63. Health assessments were conducted on a daily basis throughout the experiment using predefined faecal and respiratory scoring protocols. A range of novel, noninvasive monitoring technologies were used to examine the activity, heart rate and thermal profiles of calves on an individual basis throughout the experimental period. There were no differences in calf live weight (LWT), average daily gain (ADG) or feed conversion efficiency (FCE) in J and NJ calves between days 5 to 20. However, NJ calves consumed more MR and had more unrewarded visits to the milk feeder than J calves during this period. Although calf LWT was comparable across treatments in the week following jacket removal (days 21 to 28), both ADG and FCE tended to be greater in NJ calves. There were no treatment differences in calf LWT at the end of the study (d63). When measured over a period of 24 h and at a mean ambient temperature of 7.7°C, skin surface temperature was 6.37°C higher in J calves. Core body temperature was higher in J calves between days 5 to 20; however, there were no differences in IR eye or IR rectal temperature. No differences in lying behaviour occurred, with calves spending 18 and 17 h/day lying between days 5 to 20 and days 21 to 28, respectively. Under the climatic and management conditions described, no significant benefits to calf performance were found as a result of the provision of calf jackets to group-housed calves in the first 3 weeks of life. The higher frequency of unrewarded visits to the milk feeder in NJ calves during the first 3 weeks of life could be suggestive of a lack of satiety in these calves.     

The presence of the dam during handling prevents the socialization of young calves to humans

The effect of handling and hand-feeding of calves with or without their dams present on the calves’ subsequent response to humans was investigated using 5 groups of 10 Danish Friesian calves, each of which received a different treatment. The treatments were: calf separated from its dam immediately after birth, housed in a single pen and handled (group SH) or not handled (group S) calf adjacent to cow and handled (group CH) or not handled (C) for the first 4 days after calving. The fifth group was housed together with their dams for the first 4 days of life and then moved to single pens and handled there for the next 4 days (group C-SH). The handling treatment was carried out three times daily for 4 days and consisted of 6 min of hand-feeding with milk from a teat-bucket and patting, stroking and talking to the calf. After separation, all calves were housed in single pens. Human contact was minimised except during the treatment periods.

The approach behaviour of each calf to an unknown person was tested at days 20, 40 and 55 in their home pen. Flight distance was determined at day 55. The test at day 55 was carried out in a large single pen where the calves had been housed for 24 h prior to the test. The latency to interact (in seconds) with the person was significantly shorter (P<0.001) in all three tests for SH (13±5, 29±7 and 44±8, at days 20, 40 and 55, respectively) and C-SH (28±6, 47±17 and 70±17) compared to S (240±25, 238±33 and 173±5), C (240±28, 202±36 and 167±13) and CH (233±36, 271±29 and 128±19). The results of the latter three groups did not differ significantly. Treatment also affected the position and the orientation of the calf in the pen during the tests. Calves in SH and C-SH stood at the front of the pen and faced the person more often than calves in S, C and CH. Again, there were no significant differences between the results of the latter three groups.

The results indicate that the presence of the dam limits the effect of the handling treatment on young calves’ motivation to interact with humans. It is likely that primary socialization occurs with the dam, preventing a secondary socialization developing with humans, until the calf is isolated from the dam.     

Distribution of Cryptosporidium species isolated from diarrhoeic calves in Japan

Cryptosporidium spp. are enteric protozoan parasites that infect a wide range of hosts including humans, and domestic and wild animals. The aim of this study was to molecularly characterize the Cryptosporidium spp. found in calf faeces in Japan. A total of 80 pre-weaned beef and dairy calves' diarrhoeic faecal specimens were collected from nine different prefectures in Japan. A nested polymerase chain reaction targeting the small subunit 18S rRNA and GP60 genes were used to detect the Cryptosporidium genotypes and subtypes. 83.8% (67 out of 80) of the specimens were positive for Cryptosporidium spp.; Cryptosporidium was found in both beef and dairy calves. Cryptosporidium parvum was the predominant species, detected in 77.5% (31/40) of beef calves and 80% (32/40) of dairy calves. Cryptosporidium bovis was also detected, 5.0% (2/40) of dairy calves, and C. ryanae was also found 2.5% (1/40) of dairy calves. One mixed-species infection, 2.5% (1/40) was detected in a beef calf having C. parvum, and C. ryanae. We detected the most common subtype of C. parvum (i.e., IIaA15G2R1), as well as other subtypes (i.e., IIaA14G3R1, IIaA14G2R1, and IIaA13G1R1) that have not previously been detected in calves in Japan. Our results demonstrate the widespread diversity of Cryptosporidium infection in calves in Japan.