Demographics of the Canadian dairy industry from 1991 to 2011

A retrospective study of the demographics of the Canadian dairy industry was conducted using data derived from Statistics Canada’s Census of Agriculture from 1991 to 2011. This longitudinal study shows that Canada’s dairy industry has undergone considerable consolidation. From 1991 to 2011, the number of dairy producers and dairy farms decreased by 48.9% and 61.9%, respectively. Furthermore, this trend in consolidation is likely to continue; nearly half (45.8%) of all dairy producers in Canada were ≥ 50 y of age in 2011. Not only will most of these producers be retired by 2021, but younger producers will also exit the industry for other reasons. These findings mirror what is occurring in Canada’s cow-calf industry, underscoring that supply-managed sectors experience demographic consolidation similar to non-supply managed sectors. These substantial changes will have ramifications for the veterinary profession. There will be fewer but larger farms, and the services and knowledge demanded of veterinarians will change accordingly, which has implications for food animal veterinary education.     

An investigation of the effects of ketoprofen following rumen fistulation surgery in lactating dairy cows

Post-operative pain management following rumen surgery is not common practice. We examined the effect of providing the pain medication ketoprofen to dairy cattle following the first stage of a rumen cannulation surgery, which involves an incision in the body wall and exteriorizing and clamping the rumen. The results of this study provide clear evidence that the first stage of the surgery was painful and ketoprofen at the time of and 24 h following surgery, alleviated some, but not all, of the post-surgical pain. Pain mitigation should be included when performing flank surgery in cattle.     

Factors associated with morbidity,mortality, and growth of dairy heifer calves up to 3 months of age

Calfhood disease is an important problem on many dairy operations that can have substantial effects on heifer survival and productivity, and has economic and welfare impacts. Neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) are the most common causes of morbidity and mortality in young dairy cattle. The objective of this observational study was to investigate factors associated with the risks of morbidity and mortality, and with growth, in commercial dairy heifers calves. A total of 2874 heifer calves from 19 commercial dairy farms in Minnesota and Ontario were enrolled at 1–7 days of age and followed for approximately 3 months. Using cut-points of serum total protein of 5.2 and 5.7 g/dl, the incidences of failure of transfer of passive immunity (FTPI) were 11 and 32%, respectively. A cut-point of 5.7 g/dl was the most predictive of BRD before 5 weeks of age (sensitivity = 40%, specificity = 69%). The positive predictive value was poor (PPV = 18%), but the negative predictive value was good (NPV = 87%). A cut-point of 5.2 g/dl was most predictive of death before 5 weeks of age (sensitivity = 27%, specificity = 89%, PPV = 5%, NPV = 98%). Serum total protein during the first week of life was a poor predictor of NCD. Over 23% of calves were treated for diarrhea. Risk factors were weight at enrollment, other diseases before 2 weeks of age, and an interaction between season of birth and herd-level incidence of NCD. Almost 22% of calves were treated at least once for BRD. Factors associated with an increased risk of BRD included herd-level incidence of BRD, season of birth, navel dipping, other diseases before 2 weeks of age, failure of transfer of passive immunity, and manual control of temperature in pre-weaning housing. Administration of supplemental antibody products at birth was associated with a reduced incidence of BRD. Overall mortality was 3.5%. Risk of mortality was increased by treatment for BRD and other diseases. The mean average weight gain was 0.95 kg/day (range: 0.11–1.62 kg/day; SD = 0.2). Twinning status, FTP, treatment for NCD or other diseases, and month of birth influenced body weight. This study illustrated relationships among various diseases, mortality, and growth. Furthermore, it demonstrated the importance of colostrum for protection against BRD and improved growth performance, while bringing into question the optimal method of determining failure of transfer of passive immunity.     

Influence of Temperament Score and Handling Facility on Stress,Reproductive Hormone Concentrations,and Fixed Time AI Pregnancy Rates in Beef Heifers

The objectives were (i) to evaluate the effect of temperament, determined by modified 2‐point chute exit and gait score, on artificial insemination (AI) pregnancy rates in beef heifers following fixed time AI and (ii) to determine the effect of temperament on cortisol, substance‐P, prolactin and progesterone at initiation of synchronization and at the time of AI. Angus beef heifers (n = 967) at eight locations were included in this study. At the initiation of synchronization (Day 0 = initiation of synchronization), all heifers received a body condition score (BCS), and temperament score (0 = calm; slow exit and walk or 1 = excitable; fast exit or jump or trot or run). Blood samples were collected from a sub‐population of heifers (n = 86) at both synchronization initiation and the time of AI to determine the differences in serum progesterone, cortisol, prolactin and substance‐P concentrations between temperament groups. Heifers were synchronized with 5‐day CO‐Synch+ controlled internal drug release (CIDR) protocol and were inseminated at 56 h after CIDR removal. Heifers were examined for pregnancy by ultrasound 70 days after AI to determine AI pregnancy. Controlling for synchronization treatment (p = 0.03), facility design (p = 0.05), and cattle handling facility design by temperament score interaction (p = 0.02), the AI pregnancy differed between heifers with excitable and calm temperament (51.9% vs 60.3%; p = 0.01). The alley‐way with acute bends and turns, and long straight alley‐way had lower AI pregnancy rate than did the semicircular alley‐way (53.5%, 56.3% and 67.0% respectively; p = 0.05). The serum hormone concentrations differed significantly between different types of cattle handling facility (p < 0.05). The cattle handling facility design by temperament group interactions significantly influenced progesterone (p = 0.01), cortisol (p = 0.01), prolactin (p = 0.02) and substance‐P (p = 0.04) both at the initiation of synchronization and at the time of AI. Inter‐ and intra‐rater agreement for temperament scoring were moderate and good (Kappa = 0.596 ± 0.07 and 0.797 ± 0.11) respectively. The predictive value for calm and pregnant to AI was 0.87, and excited and non‐pregnant to AI was 0.76. In conclusion, the modified 2‐point temperament scoring method can be used to identify heifers with excitable temperament. Heifers with excitable temperament had lower AI pregnancy. Further, cattle handling facility design influenced the temperament and AI pregnancy.     

Determination of Feeder Cell‐Based Cellular Niches Supporting the Colonization and Maintenance of Spermatogonial Stem Cells from Prepubertal Domestic Cat Testes

Recently, isolation and in vitro culture of putative spermatogonial stem cells (SSCs) in the domestic cat have been conducted. However, the cellular niche conditions that facilitate the establishment and long‐term maintenance of feline SSCs (FSSCs) have not been described. Therefore, we investigated the type of feeder cells used to stimulate colony formation and growth of FSSCs among the various factors in the FSSC niche. Spermatogonial stem cells isolated from feline testes were cultured on mitotically inactivated testicular stromal cells (TSCs) derived from cats, dogs and mice, and mouse embryonic fibroblasts (MEFs). The formation and growth of colonies derived from SSCs cultured on each type of feeder cell were identified at passage 0, and the morphology, alkaline phosphatase (AP) activity and expression of SSC‐specific genes in surviving colonies were investigated at passage 4. Among these diverse feeder cells, TSCs from cat showed the greatest colony formation, growth and maintenance of FSSCs, and SSC colonies cultured by passage 4 showed a typical dome‐shaped morphology, AP activity and expression of SSC‐specific genes (NANOG, OCT4, SOX2 and CD9). Accordingly, these results demonstrate that feline TSCs could be used as feeder cells to support the establishment and maintenance of SSCs from domestic cats.     

Monitoring distances travelled by horses using GPS tracking collars

Objective The aims of this work were to (1) develop a low-cost equine movement tracking collar based on readily available components, (2) conduct preliminary studies assessing the effects of both paddock size and internal fence design on the movements of domestic horses, with and without foals at foot, and (3) describe distances moved by mares and their foals. Additional monitoring of free-ranging feral horses was conducted to allow preliminary comparisons with the movement of confined domestic horses. Procedures A lightweight global positioning system (GPS) data logger modified from a personal/vehicle tracker and mounted on a collar was used to monitor the movement of domestic horses in a range of paddock sizes and internal fence designs for 6.5-day periods. Results In the paddocks used (0.8–16 ha), groups of domestic horses exhibited a logarithmic response in mean daily distance travelled as a function of increasing paddock size, tending asymptotically towards approximately 7.5 km/day. The distance moved by newborn foals was similar to their dams, with total distance travelled also dependent on paddock size. Without altering available paddock area, paddock design, with the exception of a spiral design, did not significantly affect mean daily distance travelled. Feral horses (17.9 km/day) travelled substantially greater mean daily distances than domestic horses (7.2 km/day in 16-ha paddock), even when allowing for larger paddock size. Conclusions Horses kept in stables or small yards and paddocks are quite sedentary in comparison with their feral relatives. For a given paddock area, most designs did not significantly affect mean daily distance travelled.     

Unusual osteochondral lesions of the talus in a horse

A 2-year-old Thoroughbred gelding was evaluated for a grade 3 out of 5 unilateral hind limb lameness. Flexion of the right hock and stifle joints (spavin test) exacerbated the lameness. Response to intra-articular and perineural anaesthesia isolated the source of lameness to the tarsocrural area, despite an absence of tarsocrural joint effusion. Routine radiographic examination of the hock did not reveal any significant abnormalities. Skeletal nuclear scintigraphic evaluation revealed a focal region of increased bone activity in the proximal medial trochlear ridge of the talus. Flexed lateromedial radiographic views identified three discrete semicircular lytic lesions at the proximal articular margin of the medial trochlear ridge of the talus. Conservative management of the lesions was associated with a successful return to racing. The location and appearance of the osteochondral lesions of this report have not been previously reported and may be a manifestation of developmental orthopaedic disease and abnormal endochondral ossification. Nuclear scintigraphy and flexed lateromedial radiographic views facilitated identification of the lesions. This radiographic view is recommended when lameness is isolated to the tarsocrural joint and standard radio-graphic projections fail to identify a cause.     

Clinical use of epidural xylazine in the horse

Xylazine was administered into the epidural space of nine horses to facilitate various perineal manipulations (ie rectovaginal laceration repair, replacement of prolapsed rectum and urethral extension). The resulting caudal analgesia was sufficient for all procedures. The duration of analgesia from a single injection of epidural xylazine (0.17 to 0.22 mg/kg bodyweight) was at least 3.5 h. No horses were ataxic during or after the treatment. This trial demonstrates that xylazine given into the epidural space of horses provides prolonged regional analgesia which is sufficient for clinical use.