Production benefits from pre- and post-lambing anthelmintic treatment of ewes on commercial farms in the southern North Island of New Zealand

Abstract

AIMS: To measure the magnitude and variability in production responses to anthelmintic treatments administered to adult ewes around lambing.

METHODS: Ewes carrying twin lambs, from sheep and beef farms (eight in Year 1 and six in Year 2) in the Wairarapa region of New Zealand, were enrolled in 14 trials (part of an experiment carried out on one farm in one year). Experiment 1 compared ewes treated 2–4?weeks pre-lambing with a controlled release capsule (CRC) containing abamectin, albendazole, Se and Co, to ewes injected pre-lambing with a long-acting Se plus vitamin B₁₂ product, and to untreated ewes. Experiment 2 included these treatments, plus a CRC administered at pregnancy scanning. Experiment 3 included the same treatments as Experiment 1, plus administration of a CRC containing albendazole, Se and Co, injectable moxidectin or oral derquantel plus abamectin, all administered pre-lambing, or oral derquantel plus abamectin administered 4–6?weeks after lambing. Variables compared were ewe liveweight at weaning and pre-mating, lamb liveweight at weaning, total weight of lamb weaned per ewe and ewe dag score at weaning.

RESULTS: Ewes treated with a CRC pre-lambing were heavier than untreated ewes (mean 3.2?kg) at weaning in 12/14 trials, and pre-mating (mean 2.8?kg) in 9/14 trials (p<0.001). Compared with mineral-treated ewes the mean difference was 2.8?kg pre-lambing (9/14 trials) and 1.7?kg pre-weaning (6/14 trials). Lambs reared by treated ewes were heavier (mean 1.55?kg) at weaning in 6/14 trials (p<0.001), but there was no effect of CRC treatment on total weight of lambs weaned per ewe (p=0.507). Variation in weight of lamb weaned per ewe was largely explained by differences in lamb survival from birth to weaning (p<0.001), with no effect of CRC treatment (p>0.65).

Treatment of ewes with a CRC at pregnancy scanning was neither better nor worse than a pre-lambing treatment (p=0.065).

There was no difference in the response from treatment with either of the two CRC or moxidectin. Treatment with short-acting oral anthelmintics resulted in no consistent benefit.

CONCLUSIONS: Anthelmintic treatments administered to ewes around lambing resulted in variable responses between farms and years, which in some trials were negative for some variables, and some of the variability was due to the mineral component of the CRC. The widespread perception amongst farmers and veterinarians that anthelmintic treatment of ewes around lambing will always result in positive benefits is not supported.     

An ethogram of post-anesthetic recovery behaviors in horses: comparison of pre- and post-anesthetic behaviors

Pain management is an important post-operative concern. Pain scales may rely on the observer's subjective assessment of the level of discomfort and may not correlate with physiologic or pharmacologic measures of pain. The purpose of this study was to develop an objective measure of behavior in healthy pain-free horses recovering from anesthesia that could be used for comparison with the behavior of horses recovering from a surgical procedure.
Focal sampling with videotape and observation was done on five healthy horses before anesthesia to establish baselines. Behavioral measures included head turns, tail swishes, eyelid aperture/size, ear position, angle of neck, weight shifts, and ambulation. Physiologic measures included heart rate, respiratory rate, and temperature. The horses were anesthetized for 2 hours with isoflurane, and in the recovery stall, data were collected continuously on videotape from the time of extubation to standing. Focal sampling of 15 minutes was repeated at 1, 2, 4, and 24 hours after the horses returned to their stalls. Video data were analyzed using the Noldus Observer Video Analysis System.
A wide variation in behavior was observed between horses in the recovery stall. Observations at 1, 2, and 4 hours revealed change from the up/forward ear position to the down ear position, and a decrease in weight bearing of the hind limb from a baseline of 11–12 minutes out of 15 minutes to 7–9 minutes with an increase in toe pointing. Time spent standing was similar to baseline of 93.8%, and the neck angle was not changed from baseline of 173.5°. Values had returned to baseline at 24 hours.
Changes in behavior were induced by anesthesia alone and must be taken into consideration when evaluating analgesic treatments.     

Cholelithiasis and hyperthyroidism in a cat

A 14-year-old domestic short-hair cat presented with a history of intermittent malaise and increased drinking. A diagnosis of hyperthyroidism and cholelithiasis was made by a combination of blood testing, radiography and ultrasonography. After medical management of hyperthyroidism, thyroidectomy and cholecystectomy were successfully performed. Removed choleliths were comprised of calcium carbonate and bilirubinate. Histopathological analysis of tissue suggested low grade pancreatic and hepatobiliary disease, as well as hyperthyroidism, might have contributed to stone formation.     

Acceptance by stoats (Mustela erminea) of 1080 (sodium monofluoroacetate) in small-volume baits and its effect on behaviour and time to death

AIMS: To assess whether stoats (Mustela erminea) would eat small baits containing 0.1% sodium monofluoroacetate (1080); whether they would die from it; how long it would take to kill them; and to document the behaviour of 1080-intoxicated stoats.

METHODS: Stoats were offered 1-g baits of two semi-fluid formulations containing 0.1% 1080, presented in open dishes, and their subsequent behaviour was monitored by video and direct observation. Muscle samples from stoats that died were analysed for 1080 residues.

RESULTS: There was no significant difference between two types of bait with regard to acceptance, mortality, and time to death, and behavioural effects were similar; consequently, results from the two types of bait were combined. Twelve of 14 stoats offered the baits ate them voluntarily, and a 13th licked bait off its fur; all 13 died between 1 h 15 min and 4 h 7 min (mean 2 h 38 min) later. At first (range 29 min — 2 h 7 min, mean 1 h 1 min), their behaviour appeared to be normal. Ataxia and hyperactivity were the first behavioural signs of poisoning, and lasted 2 min — 1 h 40 min (mean 26 min). This was followed by recumbency with convulsions and rapid breathing (range 16 min to 2 h, mean 58 min), then recumbency with limited activity and progressively shallow breathing prior to death (range 1–51 min, mean 33 min). Stoats became non-responsive to a light being turned on, or to touch once recumbency became sustained.

Residues of 1080 were found in muscle tissue of all 13 dead stoats, at concentrations ranging from 0.075 μg/g in a 287-g male that died 4 h 7 min after eating only 0.74 g of bait, to 2.5 μg/g in a 254-g female that died 2 h 42 min after taking a whole 1-g bait.

CONCLUSION: Stoats will voluntarily take small (1-g) baits containing a lethal dose of 1080 at 0.1%, and die from it comparatively rapidly for a mammalian carnivore.     

Effect of N‐acetyl‐L‐cysteine Supplementation in Semen Extenders on Semen Quality and Reactive Oxygen Species of Chilled Canine Spermatozoa

The objective of this study was to evaluate the quality of chilled dog semen processed with extenders containing various concentrations of N‐acetyl‐L‐cysteine (NAC). Ejaculates from five dogs were collected, pooled and evaluated for concentration, motility, rapid steady forward movement (RSF‐movement), viability, acrosomal integrity and by the hypo‐osmotic swelling test (HOST). In addition, superoxide anion (O₂^‐?) production, hydroxyl radicals (OH^?) and total reactive oxygen species (tROS) were determined. The pool was divided into five aliquots, which were diluted to a final concentration of 66.66 × 10⁶ spermatozoa/ml with Tris‐glucose‐egg yolk extender containing one of the following concentrations of NAC (0, 0.5, 1, 2.5 or 5 mm ). The semen aliquots were chilled and preserved at 4°C. Semen quality was evaluated after rewarming at 72 h. Sperm motility was significantly higher with the 0.5 mm concentration compared with the control group (p = 0.001). Rapid steady forward movement was higher with the 0.5 and 1 mm concentrations compared with the control and 5 mm group (p < 0.001). Viability and HOST percentages were not significantly altered. Compared with the control, the 5 mm concentration showed significantly reduced percentages of spermatozoa with normal acrosomes (p = 0.049). None of the ROS values at 72 h were significantly affected by the presence of NAC in semen extenders, although all NAC concentrations showed lower O₂^‐? and OH^? values compared with the control. Only the concentrations of 1 and 5 mm inhibited the significant increase of tROS values after 72 h, compared with the fresh semen value. In conclusion, NAC supplementation of semen extenders is beneficial to semen motility of canine spermatozoa during chilling with the 0.5 mm concentration being the most effective, although no significant ROS inhibition was observed at 72 h.     

Effect of Overnight Staining on the Quality of Flow Cytometric Sorted Stallion Sperm: Comparison with Tradtitional Protocols

Flow cytometry is considered the only reliable method for the separation of X and Y chromosome bearing spermatozoa in equines. The MoFlo SX DP sorter is highly efficient, allowing the production of foals of the desired sex. However, to achieve acceptable pregnancy rates the currently used protocol requires working with fresh semen obtained close to, or at, the sorting facility. An alternative protocol was tested during two consecutive breeding seasons. Fresh stallion semen was cooled for 20 h, during which staining with Hoechst 33342 took place. On the following day, this sample was flow sorted and compared with spermatozoa from the same ejaculate that had been sexed on the previous day. All sperm parameters evaluated remained unchanged when fresh sorted and refrigerated sorted semen were compared. Pre‐sorting storage at 5°C did not alter sperm velocities nor kinetics, viability or membrane permeability, production of reactive oxygen species, mitochondrial membrane potential or DNA fragmentation index of the sorted sample. The findings open for the possibility of using semen from stallions housed far from the sorting facilities. Processed and stained sperm could be shipped refrigerated on the previous day, sorted and inseminated on the next day.     

Attitudes of veterinarians to undergraduate education in genetics and the use of genetics in veterinary occupations

A questionnaire regarding attitudes to undergraduate education in genetics and the subsequent use of that education was sent to 1000 veterinarians registered in New South Wales. Three hundred replies to the questionnaire were received and analysed. No significant difference in the perceived adequacy of courses at the four universities involved in teaching veterinary science was observed. Opinions on adequacy of education in genetics were not affected by age, sex or years since graduation. The major reason cited for lack of adequacy was that undergraduate genetics courses were not practical. Only 17 respondents stated that they were never approached for information on genetics or animal breeding, while 76 were approached more than 20 times annually for information. Eighty-three respondents claimed to deal with more than 20 cases annually that required some knowledge of genetics. The results of the questionnaire highlight the importance of genetics instruction in undergraduate veterinary education. The questionnaire responses also provide insight into how working veterinarians consider that courses in genetics could be improved.