Scrotal tick damage as a cause of infertility in communal bulls in Moretele, South Africa.

Cheryl M.E Mccrindle,Edward C Webb,Mario P Smuts,Ester A Botha,Masethe J Maime

doi:10.4102/jsava.v90i0.1966

Abstract

Calving rate in communal cattle influences both food security and socio-economics in rural households. A previous study indicated that scrotal damage caused by ticks could affect the fertility of communal bulls and reduce the annual calving rate. The objectives of the study were to investigate the annual calving rate in communal herds by counting calves during herd visits, perform breeding soundness examinations on bulls and identify adult ticks attached to their genitalia. This prospective longitudinal survey was based on participatory rural appraisal. Calving rates were estimated in cows (n = 2398) from 100 randomly selected communal herds in Moretele over 12 months in 2013, during routine visits by animal health technicians. Randomly selected bulls (n = 50) from these herds were tested for Brucella abortus, Trichomonas foetus and Campylobacter fetus subspecies venerealis. The calving rate was 35.86% (0.359). The mean scrotal circumference was 37.63 ± 3.42 cm. Total sperm motility was 78.73 ± 35.73%; progressive sperm motility was 27.39 ± 15.81% and non-progressive sperm motility was 51.34 ± 19.92%. Thirty-five of the 38 bulls examined for breeding soundness exhibited severe scrotal and preputial lesions caused by the adult ticks Amblyomma hebraeum and Hyalomma rufipes. Tick control methods used included spraying (n = 20), pour-on (n = 11), no control (n = 1) and various (n = 18). It was concluded that in Moretele genital tick damage had a more serious impact on the fertility of communal bulls than contagious diseases. Targeted acaricidal spot treatment of the genitalia of communal bulls to prevent infestation is recommended, as tick control strategies used by farmers appeared to be inadequate.

Highlights

In areas of South Africa with low soil fertility and rainfall of less than 500 mm per year, commercial and communal extensive beef production systems are sustainable options (Grobler 2015; Musemwa et al 2008)
The aim of this study was to use a participatory farming systems approach to investigate the possible links between tick damage to genitalia and bull fertility in communal herds in the Moretele District, North West Province (NWP)
Over the 12-month study period in 2013, 860 calves were born to the 2398 adult cows and 75 bulls counted at the beginning of the survey resulting in a calving rate of 35.86%

Summary

Introduction

In areas of South Africa with low soil fertility and rainfall of less than 500 mm per year, commercial and communal extensive beef production systems are sustainable options (Grobler 2015; Musemwa et al 2008). According to the Department of Agriculture Forestry and Fisheries website (DAFF 2019), the recommended calving percentage for beef cattle in South Africa is 85%. Bull fertility is known to influence calving rates in communal cattle rearing systems in South Africa (Mokantla et al 2004; Sekokotla 2004). Fertility in range bulls is assessed by using breeding soundness examinations (Alexander 2008; Chenoweth & McPherson 2016; Chenoweth, Spitzer & Hopkins 1992; Irons, Nothling & Bertschinger 2007). Infectious diseases that could affect the calving rate in the study area are bovine brucellosis, bovine genital campylobacteriosis and bovine trichomoniasis (Mokantla et al 2004)

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Conclusion