A longitudinal study on the effect of lambing season on the periparturient egg rise in Ontario sheep flocks

Protein Supplementation as a Nutritional Strategy to Reduce Gastrointestinal Nematodiasis in Periparturient and Lactating Pelibuey Ewes in a Tropical Environment

The study was carried out to evaluate the effect of energy and protein supplementation on parasitological and hematological response during peripartum and lactation of productive and non-productive Pelibuey ewes in a tropical environment. Forty-eight Pelibuey ewes aged 3–5 years and with a body weight of 31 ± 5 kg were used. Four groups of 12 ewes, including non-pregnant and productive ewes, were formed. A factorial treatment design was formulated, where two levels of energy (low, 9.6 MJ/kg, n = 24; and high, 10.1 MJ/kg, n = 24) and two levels of protein (high, 15% crude protein in diet, n = 24; and low, 8% crude protein in diet, n = 24) were studied. Fecal and blood samples were collected to determine the fecal egg count (FEC) of gastrointestinal nematodes (GIN), packed cell volume (PCV) and peripheral eosinophil (EOS) count. These variables were rearranged with respect to the lambing date in a retrospective study. The high dietary protein level had a significant effect on reducing the FEC and increasing the PCV of ewes during lactation, in comparison with animals fed with the low protein level. Differences in the study variables were attributed to physiological stage. Lactating ewes showed the highest FEC values (2709 ± 359 EPG), the lowest PCV values (21.9 ± 0.7%) and the lowest EOS (0.59 ± 0.6 Cells × 10³ µL). It is concluded that high levels of dietary protein improve the hematological response and reduce the FEC in Pelibuey ewes under grazing conditions. The non-pregnant ewes maintained some resilience and resistance to GIN infection compared to productive ewes.

Effects of lambing season on nematode faecal egg output in ewes

In this study, we assessed the occurrence of a periparturient rise (PPR) in winter and spring lambing ewes in Sweden and where nematode egg excretion patterns were investigated mainly for diagnostic purposes. Gastrointestinal nematodes and Haemonchus contortus presence were monitored in parallel in all animals in each experimental group on four farms in samples that were collected mainly when the animals were stabled. Faecal examinations of the same animals were conducted on four sampling occasions between January and June 2018 Each group consisted of 12 crossbreed ewes of similar genotype. One group's peak lambing was in January or February (early), and the other in March or early May (late). The first (S1) and third samples (S3) were from approximately one to two weeks before parturition in the early (winter lambing) and late (spring lambing) group respectively, whereas the second (S2) and fourth samples (S4) were collected approximately three to five weeks post-parturition in the same groups. During the course of the study, there was a significant rise in faecal egg counts (FEC) in both groups on all farms. On three farms with a substantial amount of Haemonchus, we observed a difference in the egg excretion patterns between the two groups of ewes as revealed by a significant interaction between the sampling point and lambing period. Also, when samples corresponding to each other in relation to the number of weeks that had elapsed post-parturition (three to five weeks post-parturition, S2 for early and S4 for late) were compared, FEC were significantly lower in the early group lambing in winter than the late group lambing in spring. This indicates that besides lambing, the rise in nematode egg count is also influenced by other factors unrelated to the lambing period, such as the increased daylight in spring. Due to study limitations, we cannot provide a more detailed explanation for this, but only state that the rise appeared to be more closely linked to season than physiology as measured by day relative to parturition. Still, our results suggests that when turned out, winter lambing ewes contribute to pasture contamination to a lesser extent than those lambing in spring. These results will be used in stipulating evidence-based advice to farmers in their flock management to reduce use of anthelmintics, and at the same time efficiently produce prime lambs.

Correlation of subclinical gastrointestinal nematode parasitism with growth and reproductive performance in ewe lambs in Ontario

Infection with gastrointestinal nematode parasites (GINs) is an important cause of productivity loss on sheep farms in Ontario and worldwide. However, efforts to quantify the effect of GIN infection on growth have demonstrated mixed results. Furthermore, there has been limited investigation of their effect on reproductive performance. This study evaluated the effect of subclinical GIN parasitism on growth and reproductive performance of ewe lambs under Ontario grazing conditions. Rideau cross ewe lambs (n = 140) born in spring 2016 on a farm in central Ontario were followed for two years from before weaning through to November 2017, including their first lambing and lactation. These animals grazed from May to November of each year and were sampled every 6-8 weeks during both grazing seasons and once at mid-gestation in March 2017. At each sampling the ewe lambs were weighed, body condition scores assigned, fecal egg counts (FECs) performed, and pasture samples collected to assess number of infective GIN larvae. Study animals with a FEC of 500 eggs per gram or higher were selectively treated with anthelmintics to prevent morbidity and mortality. Fecal samples were cultured to determine infecting GIN species, and climate data were obtained from a weather station 26 km away from the farm. Precipitation levels and numbers of infective larvae on pasture were low during the first grazing season but were more typical of Ontario conditions in the second grazing season. The three most common GIN species were Haemonchus contortus, Teladorsagia circumcincta, and Trichostrongylus spp. General linear mixed models were generated for weight change over time, litter size at lambing, and weaning weights of offspring. Despite moderate peak GIN burdens in both grazing seasons, FEC was not significantly associated with weight change or litter size, apart from periparturient egg rise in study ewe lambs with larger litters (p = 0.05). Significant positive quadratic and negative linear associations were identified between late lactation FECs and offspring weaning weights; the association between FECs and weaning weights changed from negative to positive at a FEC of 361 eggs per gram. These results indicate that when GIN burdens are moderate as evidenced by fecal egg counts and infection is subclinical, there appears to be low to no impact on growth and reproductive performance in ewe lambs in the first 18 months of life. This suggests that when GIN parasitism is regularly monitored and controlled using targeted selective treatment, animal performance is minimally affected.

Cardiorespiratory physiological perturbations after acute smoke-induced lung injury and during extracorporeal membrane oxygenation support in sheep

Background: Numerous successful therapies developed for human medicine involve animal experimentation. Animal studies that are focused solely on translational potential, may not sufficiently document unexpected outcomes. Considerable amounts of data from such studies could be used to advance veterinary science. For example, sheep are increasingly being used as models of intensive care and therefore, data arising from such models must be published. In this study, the hypothesis is that there is little information describing cardiorespiratory physiological data from sheep models of intensive care and the author aimed to analyse such data to provide biological information that is currently not available for sheep that received extracorporeal life support (ECLS) following acute smoke-induced lung injury. Methods: Nineteen mechanically ventilated adult ewes undergoing intensive care during evaluation of a form of ECLS (treatment) for acute lung injury were used to collate clinical observations. Eight sheep were injured by acute smoke inhalation prior to treatment (injured/treated), while another eight were not injured but treated (uninjured/treated). Two sheep were injured but not treated (injured/untreated), while one received room air instead of smoke as the injury and was not treated (placebo/untreated). The data were then analysed for 11 physiological categories and compared between the two treated groups. Results: Compared with the baseline, treatment contributed to and exacerbated the deterioration of pulmonary pathology by reducing lung compliance and the arterial oxygen partial pressure to fractional inspired oxygen (PaO 2/FiO 2) ratio. The oxygen extraction index changes mirrored those of the PaO 2/FiO 2 ratio. Decreasing coronary perfusion pressure predicted the severity of cardiopulmonary injury. Conclusions: These novel observations could help in understanding similar pathology such as that which occurs in animal victims of smoke inhalation from house or bush fires, aspiration pneumonia secondary to tick paralysis and in the management of the severe coronavirus disease 2019 (COVID-19) in humans.

Epidemiology and Control of Gastrointestinal Nematodes of Cattle in Northern Climates

Parasite species infecting cattle throughout northern North American are generally the same as those found throughout North America. Throughout Canada, cattle are primarily infected with Ostertagia ostertagi and Cooperia oncophora, whose larvae survive cold winters within soil of pastures. Overwintering larvae of these species maintain a temporary population of refugia available in spring to grazing cattle. Cattle from northern United States are also infected with Cooperia punctata and Haemonchus placei, whose larvae cannot survive cold winters within pastures. Anthelmintics with persistent activity are used during spring to recover some of these losses; however, anthelmintic resistance limits effectiveness of this strategy.

Influence of the physiological stage of Blackbelly sheep on immunological behaviour against gastrointestinal nematodes

The influence of the physiological stage of a Blackbelly flock against natural infection by gastrointestinal parasitic nematodes (GIN) was investigated. Data on serum and saliva IgA levels and peripheral cellular immune response were recorded in 51 sheep for 6 months. The flock was divided based on their physiological stage as follows: a) pregnant ewes, b) lactating ewes, c) non-pregnant ewes, d) pre-weaning lambs, e) growing lambs and f) replacement sheep. Additionally, sheep were classified based on the parasite infection as stabled or grazing management system as follows: g) non-infected stabled sheep, h) infected and stabled sheep and i) infected grazing sheep. Faeces and blood samples were collected every fifteen days. The percentage of packed cell volume (PCV), plasma protein, (PP) and leucocyte differential counts (LDC) were recorded. Likewise, serum and saliva IgA levels were measured by the indirect ELISA technique. The number of GIN eggs excreted per g of faeces (EPG) was also determined using the McMaster technique. Data were analysed using the SAS program to identify fixed effect of physiological stages, infection time and interactions. Results showed high EPG values in stabled lactating ewes (2764) and in growing lambs (2950-4550 EPG). Pregnant ewes had higher PCV values (27%) than lactating ewes (23.5%). Infected lambs showed low PCV values (28.5%) and high PP values (5.9 g/dL) compared with non-infected lambs (31% PCV and 5.6 g/dL PP). The two most abundant GIN species identified were Haemonchus contortus (91%) and Trichostrongylus colubriformis (81%). Pregnant and non-pregnant ewes showed 29% and <20% of IgA values, respectively. High EPG, low IgA and eosinophils counts were observed until 180 days of age in infected lambs. In conclusion, the group of infected lactating ewes and lambs showed susceptibility to GIN than the other groups, including the pregnant ewes.

Dynamics of faecal egg count in natural infection of Haemonchus spp. in Indian goats

Aim:

Dynamics of faecal egg count (FEC) in Haemonchus spp. infected goats of two Indian goat breeds, Jamunapari and Sirohi, in natural conditions was studied and effects of genetic and non-genetic factors were determined.

Materials and Methods:

A total of 1399 faecal samples of goats of Jamunapari and Sirohi breeds, maintained at CIRG, Makhdoom, Mathura, India and naturally infected with Haemonchus spp., were processed and FEC was performed. Raw data generated on FEC were transformed by log_e (FEC+100) and transformed data (least squares mean of FEC [LFEC]) were analyzed using a mixed model least squares analysis for fitting constant. Fixed effects such as breed, physiological status, season and year of sampling and breed × physiological states interaction were used.

Result:

The incidence of Haemomchus spp. infection in Jamunapari and Sirohi does was 63.01 and 47.06%, respectively. The mean LFEC of both Jamunapari and Sirohi (does) at different physiological stages, namely dry, early pregnant, late pregnant early lactating and late lactating stages were compared. Breed, season and year of sampling had a significant effect on FEC in Haemomchus spp. infection. Effect of breed × physiological interaction was also significant. The late pregnant does of both breeds had higher FEC when compared to does in other stages.

Conclusion:

Breed difference in FEC was more pronounced at the time of post kidding (early lactation) when sharp change in FEC was observed.

Exploiting parallels between livestock and wildlife: Predicting the impact of climate change on gastrointestinal nematodes in ruminants

Global change, including climate, policy, land use and other associated environmental changes, is likely to have a major impact on parasitic disease in wildlife, altering the spatio-temporal patterns of transmission, with wide-ranging implications for wildlife, domestic animals, humans and ecosystem health. Predicting the potential impact of climate change on parasites infecting wildlife will become increasingly important in the management of species of conservation concern and control of disease at the wildlife-livestock and wildlife-human interface, but is confounded by incomplete knowledge of host-parasite interactions, logistical difficulties, small sample sizes and limited opportunities to manipulate the system. By exploiting parallels between livestock and wildlife, existing theoretical frameworks and research on livestock and their gastrointestinal nematodes can be adapted to wildlife systems. Similarities in the gastrointestinal nematodes and the life-histories of wild and domestic ruminants, coupled with a detailed knowledge of the ecology and life-cycle of the parasites, render the ruminant-GIN host-parasite system particularly amenable to a cross-disciplinary approach.