Michael Chimonyo

Relationships between tick counts and coat characteristics in Nguni and Bonsmara cattle reared on semiarid rangelands in South Africa

Indigenous Nguni cattle are adapted to the semiarid rangeland and appear to be resistant to ticks; however, the mechanism for tick resistance is yet to be established. To understand tick resistance in cattle, relationships among skin thickness, hair length, coat score, and tick counts were estimated in Nguni (n=12) and Bonsmara (n=12) heifers on semiarid rangelands of South Africa. The tick species observed to infest the heifers were Rhipicephalus (Boophilus) decoloratus (frequency: 76%), Rhipicephalus (Boophilus) microplus (9%), Amblyomma hebraeum (5%), Rhipicephalus appendiculatus (5%), Rhipicephalus evertsi evertsi (3%), and Hyalomma marginatum (2%). Nguni heifers had lower (P<0.05) log(10) (x+1)-transformed coat scores (0.6±0.01), hair length (1.4±0.01), and tick counts (1.4±0.03) than Bonsmara heifers whose log(10) (x+1)-transformed coat score, hair length, and tick count values were 0.7±0.01, 1.5±0.01, and 1.8±0.02, respectively. The skin thickness between the two breeds were similar (P>0.05). There was a positive linear (P<0.05) relationship between log(10) (x+1) tick counts and log(10) (x+1) coat score in the Nguni (y=1.90x-0.40) and a quadratic relationship in the Bonsmara (y=-7.98x(2)+12.74x-3.12) breed. It was concluded that the smooth coats may be one of the important mechanisms of tick resistance in the indigenous Nguni breed. Determination of genetic resistance to ticks in the Nguni breed is recommended as this will give more specific indication to the mechanism of host resistance in this breed.

Towards a genomics approach to tick (Acari: Ixodidae) control in cattle: A review

Ticks and tick-borne disease (TBD) are major challenges to cattle production in the tropics and subtropics. Economic losses associated with ticks amount to billions of dollars annually. Although efforts to eradicate ticks and TBD using chemical control strategies have been implemented in many developing countries for decades, these acaricides are costly, and cattle susceptibility to ticks remains unchanged. Traditional breeding methods, where the farmer selected animals using records to improve the host genetic resistance to ticks (HGRT), are less than fully effective and time consuming. The HGRT has been reported in literature. To date, solutions to fight ticks and TBD are still unclear. Development of single-nucleotide polymorphism (SNP) technologies has created an opportunity to estimate breeding values of animals from DNA samples. The use of SNP technology for genomic selection allows information retrieval from the genotype even before the gene is expressed; thus potentially giving farmers the ability to make selection decisions on HGRT at an earlier age. This review discusses factors that affect HGRT, breeding selection, immunology, and genomic approaches and their application to improve HGRT in order to enhance livestock production.

Cutaneous hypersensitivity responses to Rhipicephalus tick larval antigens in pre-sensitized cattle

Nguni cattle are known to be more resistant to ticks than Bonsmara cattle, even if the immunological mechanisms responsible for this phenomenon are not fully understood. Cutaneous hypersensitivity responses to unfed larval extracts (ULE) of the ticks Rhipicephalus decoloratus and Rhipicephalus microplus were investigated in Nguni and Bonsmara cattle to improve knowledge on the immunity to ticks. Hypersensitivity reactions were induced by intradermal inoculation of 0.1ml of ULE of R. decoloratus and R. microplus ticks (50μg protein) in the right and left ear, respectively, of 8-9-month-old Nguni (n=11) and Bonsmara (n=9) heifers. Ear thickness was measured using callipers before and 0.5, 1, 6, 24, 48, and 72h post inoculation (PI). Bonsmara cattle showed a more intense immediate reaction with maximum response at 1h PI and no delayed hypersensitivity reaction. Nguni heifers, conversely, presented a less intense immediate reaction with maximum response at 1h PI, and a delayed hypersensitivity reaction at 72h PI. Reactions to R. decoloratus ULE produced a more intense skin response than to R. microplus in both breeds at all time intervals. Nguni cattle showed lower tick infestation indicating higher tick resistance than Bonsmara cattle. Delayed hypersensitivity reaction could be associated with superior tick resistance in the Nguni breed, while immediate hypersensitivity reaction could be associated with increased tick susceptibility in the Bonsmara breed. This study indicates the need for further investigations on the correlation of tick resistance and cellular immune responses to tick infestation in Nguni cattle.

Effect of sunflower cake supplementation on meat quality of indigenous goat genotypes of South Africa.

The effect of four castrated goat genotypes and sunflower cake supplementation on goat meat quality was determined. Supplemented Boer (BOR) and Xhosa-Boer cross (XBC) goats had significantly higher (P<0.05) SLW and CDM than non-supplemented groups. The Xhosa lop-eared (XLE) and Nguni (NGN) goats had higher pH24 (P<0.05) than BOR and XBC goats. For each genotype, the sunflower cake supplemented and non-supplemented goats had similar a* values, except for the XLE goats. In the XLE goats, the a* values were lower in the sunflower cake supplemented goats. Sunflower cake supplemented BOR goats had higher L*values than their non-supplemented counterparts (P<0.05). The sunflower cake supplemented BOR and NGN goats also had higher b* values as compared to their non-supplemented counterparts. In comparison with the Boer goat, the XLE and NGN goats had lower CDM, L* and WBF values but generally had higher CL and a* values. Sunflower cake supplementation improved meat quality attributes of the goats.

Cattle Commercialization in Rural South Africa: Livelihood Drivers and Implications for Livestock Marketing Extension

Abstract Commercialization of livestock farming systems remains a challenge in rural South Africa. Recent empirical evidence places agricultural extension at the forefront of policy strategy to address this challenge. This study applies the sustainable livelihood framework (SLF) to quantitatively analyze the factors confounding participation in cattle markets for the purpose of informing agriculture extension programming. Based on a dataset compiled from a household survey of 230 randomly selected smallholder cattle farmers in Okhahlamba Local Municipality (OLM), a Double-Hurdle econometric estimation technique is used to determine factors within the SLF influencing market participation and supply volumes decisions. The results reveal that the low rate of market participation could be explained by the broader aspects of livelihoods of smallholder cattle farmers, including limited access to financial, social and natural capital, as well as the difference in livelihood strategies and motivations. Based on these findings, the study draws the implications for the design of livestock extension programs in OLM, and South Africa in general.

Efficacy of Mozambican bentonite and diatomaceous earth in reducing the toxic effects of aflatoxins in chicks

The effectiveness of diatomaceous earth (DE) and bentonite clay (BC) in reducing the toxic effects of aflatoxin B1 (AFB1) in chicks was assessed. A total of 150 day-old male broiler chicks were assigned to six dietary treatments, with 5 replicate pens of five chicks per treatment. Dietary treatments were: (1) a positive control basal diet (BD) containing no AFB1, no BC and no DE; (2) BD + 0.50% BC but with no AFB1 and DE; (3) BD + 0.50% DE but with no AF and BC; (4) BD + 2 mg AFB1/kg diet but with no BC and DE; (5) BD + 0.50% BC + 2 mg AFB1/kg diet but with no DE; and (6) BD + 0.50% DE + 2 mg AFB1/kg diet but with no BC. Compared with controls, feed intake (FI) and body weight gain (BWG) were depressed (P<0.05) in chicks fed AFB1, with greater reduction in FI and BWG observed in birds fed the AFB1 plus 0.50% DE diet. Feed conversion ratio was similar. Chicks fed AFB1 alone had increased (P<0.05) relative liver weights compared to all other dietary treatments except for chicks fed AFB1+ DE. Chicks fed AFB1...

A comparison of faecal microbial populations of South African Windsnyer-type indigenous pigs (SAWIPs) and Large White × Landrace (LW × LR) crosses fed diets containing ensiled maize cobs

Faecal microbial communities in South African Windsnyer-type indigenous pigs (SAWIPs) and Large White × Landrace (LW × LR) crosses were investigated using high-throughput sequencing of the 16S rDNA genes. The faecal microbial communities in LW × LR crosses and SAWIPs fed control (CON) and high maize cob (HMC) diets were evaluated through parallel sequencing of 16S rDNA genes. Butrivibrio, Faecalibacterium and Desulfovibrio, although present in LW × LR pigs, were absent from the SAWIP microbial community. Bacteroides, Succiniclasticum, Peptococcus and Akkermansia were found in SAWIPs but not in LW × LR crosses. The ratios of Bacteroidia to Clostridia on the CON and HMC diets were similar (0.37 versus 0.39) in SAWIPs but different (0.24 versus 0.1) in LW × LR crosses. The faecal microbial profiles determined were different between the LW × LR and SAWIP breeds but not between pigs fed the CON and HMC diets. The composition of faecal bacterial communities in SAWIPs was determined for the first time. The differences in microbial communities detected may explain the enhanced ability of SAWIPs to digest fibrous diets compared with the LW × LR crosses.

Conservation and utilisation of indigenous chicken genetic resources in Southern Africa

The opportunities for sustainable utilisation and conservation of chicken genetic resources in Southern Africa need to be addressed. Indigenous chickens are an important animal genetic resource amongst resource-limited rural communities of Southern Africa. They play an important socio-economic role in traditional and religious ceremonies of rural households. They are important in customary rites, such as gift payments. Although the productivity of indigenous chickens in terms of growth and number of eggs per hen per year is low, its production is attained with minimal labour and rearing inputs. The low inputs and, consequently, low risk is one of the major advantages of indigenous chickens production. The conservation of these valuable chicken genetic resources is necessary in the light of the rapid loss of indigenous breeds and strains through commercial dilution and breed replacement. All varieties of domestic species and species with potential for domestication are considered to be important candidates for conservation. Indigenous chicken populations with economic potential, scientific use and cultural or aesthetic interest are of particular importance but all indigenous chickens which are unique and endangered should be incorporated into conservation efforts. This phenotypic information could be useful to standardise the different phenotypes within a region or country and design some criteria for characterisation and description of the indigenous chicken populations into breeds. Molecular markers are an indispensable tool to understand the genetic structures of populations. The assessed phenotypic coupled with genetic information could be a powerful tool towards the promotion of conservation and utilisation of indigenous chicken genetic resources.

Effect of dietary supplementation with Acacia karroo leaves on fatty acid profiles and consumer sensory attributes of Xhosa lop-eared goats under artificial haemonchosis

The effect of Acacia karroo supplementation on fatty acid profiles and sensory attributes of Xhosa lop-eared goats meat was evaluated in 18 4-month-old goats exposed to a single dose of 6000 L3 Haemonchus contortus larvae. The goats were allotted into two groups: non-supplemented (NSP) and supplemented (AK). The AK goats received 200 g of fresh A. karroo leaves. At the end of the experiment, all the goats were slaughtered to determine the fatty acid profiles and sensory perceptions. Faecal larval counts decreased significantly in the AK group as the infection progressed, while it increased in the NSP group. At necropsy, the NSP group had significantly higher worm counts than the AK group. The AK group contained significantly higher (P < 0.05) amounts of intramuscular fat and had almost twice (P < 0.05) the total polyunsaturated fatty acids and polyunsaturated fatty acid/monounsaturated fatty acid ratio. Furthermore, the AK goats also had higher amounts (P < 0.05) of n-3. Mean sensory scores for juiciness and tenderness were superior in the AK goats (P < 0.05). In conclusion, A. karroo supplementation positively influenced the fatty acid composition and sensory attributes of chevon from goats infected with H. contortus.

Effect of parity on the proximate composition and fatty acid profile of milk from Nguni cattle grazing on natural pastures

The objective of the study is to establish the effect of parity on milk composition and fatty acid profiles of Nguni cattle milk. Forty-four Nguni cows with parities ranging from 1 to 13 were included in this study. The cows were grouped to three parity groups: parity group 1 (parity 1 to 5), parity group 2 (parity 6 to 9) and parity group 3 (parity 10 to 13). Samples of the milk were collected in a single day and the milk was analyzed using gas chromatography. Parity had no effect of proximate composition (fat, DMC and moisture %) on milk. The fatty acids (FA) present in the milk of the three parity groups were primarily palmitic (33.3 to 40.5%), oleic (16.3 to 20.3%), myristic (12.5 to 13.2%) and stearic (10.8 to 11.7%) acids, in decreasing order of proportion. Milk from parity group 3 cows contained significantly (p < 0.05) higher proportions of butyric, myristoleic, oleic, eicosenoic, conjugated linoleic acid (CLA), arachidonic and eicosopentaenoic acids when compared with the other two parity groups. Parity group 3 also had significantly (p < 0.05) higher values for total SFA, MUFA, PUFA, omega 3 fatty acids and n-6/n-3 ratio than the other two parity groups. Cows in higher parities generally have higher values for individual fatty acids when compared to those in lower parities. Parity is therefore, an important factor that must be considered when assessing milk quality in Nguni cows. Key words : Conjugated linoleic acid, fat content, harsh environment, fatty acid profile, milk composition.