Haematological changes in transhumant Baruwal sheep (Ovis aries) grazing in the western Himalayan mountains in Nepal

Abstract

Transhumance pastoralism is a traditional sheep management strategy adopted by the herders in the Himalayas to address environmental stress. The changes in haematological parameters in the transhumant sheep may well give insights of changes in physiological changes at pasture sites of various elevations in the transhumance cycle. For that purpose, 32 healthy Baruwal sheep were selected and divided into four groups: male (8) below 1 year, male (8) greater than 1 year, female (8) below 1 year, and female (8) greater than 1 year; the animals were selected based on similarity on body weight within the groups. The herd was clinically inspected for the presence of any infection. Adaptation period was set for 3 weeks at each pasture site. The blood samples were taken from designated groups at both grazing sites, i.e. from low (2431 m.a.s.l) to high stopover (3885 m.a.s.l) at the seventh day of the experimental period. Climatic data were recorded at both altitudes over the period of measurements from manually installed weather stations. Later, the herbage species were collected based on the visual sign of grazing at both sites and subjected to chemical composition analysis. The research results revealed that RBC (red blood cell), Hb (Haemoglobin), and PCV (packed cell volume) were significantly increased (p < 0.05) at high altitude, while MCH (mean corpuscular haemoglobin) and MCHC (Mean corpuscular haemoglobin concentration) were higher at low altitude. Sex and age had a similar effect (p > 0.05) on haematologic parameters, except for PCV and MCH. The altitude had a big impact on leucocyte (p < 0.05), being greater at low altitude than high, which could be an indicator of the increased immunologic response at low altitude irrespective of age and sex. The research result revealed the changing haematological responses of Baruwal sheep to changing pasture sites at different altitudes in the transhumance movement. The results further gave a hint of the nutritional stress at low altitude when the herd arrives in the winter season. It is rather difficult to draw an immediate conclusion that pasture quality might be the contributory issue for a decline in the nutritional status of grazing sheep when the herbage species vary by altitude. The measurement of blood metabolic stressors could further facilitate description of the nutritional stress alongside the transhumance when the grazing species and quality are different. Strategic feed supplementation for a much better performance of Baruwal sheep is needed at low altitude to deal with the declined herbaceous quality during winter.