All the indigenous cattle of Pakistan belong to Zebu (one-humped) cattle (Bos indicus). There are 15 recognized indigenous breeds of cattle which constitute 43% of the total cattle population in the country. Hefty work has been documented on many aspects of Sahiwal and Red Sindhi breeds of cattle in their respective local climates which have rightly gained them an international fame as being the vital tropical milk breeds of Pakistan. However, scanty work has so far been reported on reproductive indices of other indigenous cattle breeds of Pakistan such as Dajal, Cholistani etc under their local climatic conditions, and their potential still remains unearthed. Hence, it is the dire need of time to comprehend the urgency of protection and propagation of the indigenous cattle breeds of Pakistan at every front.
Following the global lead, an effort has been made through the present study to highlight a formerly neglected indigenous cattle breed of Pakistan- Cholistani- being reared by the nomadic herders of the Cholistan desert, Pakistan. The study was executed with a specific objective to assess baseline data, seasonal variations and correlations between various non invasive, readily measurable reproductive [age, body weight (BW) and orchidometric parameters viz. scrotal circumference (SC), scrotal skin fold thickness (SSFT), average testicular length (Avg L), average testicular width (Avg W) and paired testicular volume (PTV)], seminal (fresh semen and seminal plasma) and haematobiochemical attributes of Cholistani AI bulls (n=06). Keeping in view the prevailing climatic conditions of the study area, 4 seasons of 2 months duration each were defined as i) stress free autumn (October-November), ii) stressful winter (December-January), stressful dry summer (May-June) and iv) stressful wet summer (July-August).
The overall mean values (± SEM) for age, BW, SC, SSFT and PTV in the present study were 92.83±2.63months, 527.55±4.5kg, 35.39±0.28cm, 1.03±0.02cm and 851.84±16.34cm3, respectively. The BW was recorded to be significantly lower (P<0.05) during the stress free autumn (507.08±8.26kg), however no significant difference was found in the remaining stressful seasons of winter, dry and wet summer. The SSFT was significantly higher (P<0.05) in stress free autumn (1.07±0.04cm) and winter (1.13±0.05cm) being followed by that in wet summer (0.97±0.02cm) and dry summer (0.94±0.03cm). SC and PTV were found to be constant during all the study seasons with no significant variation. Significantly positive correlations (P<0.01) were noticed between various traits.
The overall mean values (± SEM) for ejaculatory volume, number of ejaculates per bull, mass motility, individual sperm motility, number of dozes frozen per bull, sperm concentration, live sperm, morphologically normal sperm and those with acrosome integrity in the present study were 4.92±0.14mL, 1.89±0.02, 2.26±0.06, 63.51±1.03%, 208.26±8.42, 989.73±27.4million/mL, 86.74±0.55%, 86.34±0.51% and 86.64±0.48%, respectively. In general, all the seminal attributes revealed significantly (P<0.05) better results in stressful seasons as compared to stress free season, with the exception of number of ejaculates per bull which was not affected significantly by seasons.
In terms of semen production, a total of 39778 doses of 0.5 mL straws were frozen during the study period. Significantly higher number of doses per bull (P<0.05) was frozen during dry (245.37±17.84) and wet summer (250.37±17.75) as compared to autumn (191.4±14.22) and winter (143.92±11.25); the difference between the latter two seasons was also significant, while it was non significant between the former two seasons
Regarding the subjective analysis of spermatozoa, higher (P<0.05) mean values were recorded for all three parameters (live, morphologiclly normal and acrosome intact sperm) during stressful winter and dry summer as compared to wet summer and autumn, the difference between the former two seasons was, however, non significant. Moreover, mean values for these attributes were significantly higher during wet summer as compared to autumn. Amongst the physical attributes of semen, only mass motility revealed a significantly positive (P<0.01) correlation with individual sperm motility (r 0.619). However, regarding the subjective analyses, live sperm had a positive correlation with normal (r 0.848) and with acrosome integral sperm (r 0.790).
In seminal plasma chemistry, the overall mean values (± SEM) for Na+, K+, cholesterol and glucose recorded in the present study were 236.41±4.2, 142.95±3.81, 152.02±3.17 and 127.22±3.65 mg%, respectively. Amongst these, Na+ was significantly higher (P<0.05) during dry summer (270.35±8.89mg%) whereas K+ was higher in dry summer (169.1±5.54mg%) and winter (154.80±6.29mg%). Cholesterol and glucose were found to be significantly elevated (P<0.05) during dry summer season being 173.7±4.24 and 147.95±7.74mg%, respectively. Na+ had a significantly positive (P<0.05) correlation with glucose (r 0.232). Similarly, positive (P<0.01) correlations were seen for K+ with Na+ (r 0.341) and cholesterol (r 0.390).
The overall mean values (± SEM) for Hb, TEC, PCV, MCV, MCH and MCHC recorded for the Cholistani AI bulls in the present study were 12.24±0.15mg/dL, 6.28±0.82×106/µL, 37.3±0.4%, 59.77±0.61fL, 19.58±0.2pg and 32.89±0.33g/dL, respectively. Regarding the white blood cell values, the overall means (± SEM) for TLC, neutrophils, lymphocytes, monocytes and eosinophils were 7.58±0.17×103/µL, 40.45±1.05%, 53.2±0.85%, 4.05±0.47% and 2.3±0.26%, respectively. DLC, in the present study, revealed that the lymphocytes were the predominant leukocytes followed by neutrophils. No significant effect (P<0.05) of season was noticed on any of the red blood cell values studied. However, TLC amongst the white blood cell values was found to be significantly higher in dry summer (8.16±0.28×103/µL).
The overall mean values (± SEM) for blood serum NA+, K+, cholesterol and glucose recorded for the present study were 130.73±0.91, 7.37±0.11, 82.8±1.52 and 75.22±2.04mg%, respectively. Correlation analysis revealed significant positive correlations between mass and individual sperm motility, morphologically normal and live sperm and sperm acrosome integrity and live sperm (P<0.01). Among biochemical attributes of seminal plasma, Na+ and K+, cholesterol and K+ and glucose and Na+ were correlated (P<0.01). Only seminal plasma cholesterol was positively correlated with ejaculatory volume (P<0.01).
An overall mean value of 5.81±0.32ng/mL was recorded in the present study for testosterone being non significantly effected by seasons. All its correlations with all attributes studied were found to be non significant.
In conclusion, various physical and biochemical attributes of Cholistani bull semen were better in stressful seasons as compared to stress free season. The acceptable quality of semen of Cholistani bulls recorded during wet/dry summer in the present study is an indicative of the fact that this breed has an innate ability of being well adapted to the harsh, hot desert climate. Furthermore, the present study revealed that the Cholistani breeding bulls have an amazing tendency to maintain most of their haematobiochemical parameters at a near constant level without showing much variation during stress free or stressful times.