South African Indigenous Goats Research Articles

Live animal and carcass characteristics of South African indigenous goats

Eighty-nine intact male, castrates and female South African indigenous goats in three age groups (0, 2 - 6 and 8 permanent incisors) and two pre-slaughter conditioning groups; namely, the non-conditioned which were slaughtered within three months of purchase and the pre-slaughter conditioned, which were slaughtered 6 - 10 months after purchase or birth were used. The effect of sex, age and pre-slaughter conditioning on live animal, carcass dimensions and carcass composition were evaluated. The goats were large with live weight, carcass weight and carcass dimensions in the range of the large breeds of southern Africa. They had a high lean and low fat content. Intact males were suited for high chevon yield because they were heavy, had a high lean and low fat content, and losses during dressing and chilling were reduced by improved nutrition. Goats between 2 - 6 teeth yielded heavy carcasses that were comparable to goats in the 8-teeth group, and had proportionately more lean and less carcass fat. The hind limb was ideal for high lean and low fat, high value cuts but the dorsal trunk was bony and yielded less lean. Pre-slaughter conditioning improved the overall size of the goats and reduced the losses during slaughter and chilling. It also improved the lean/bone and lean and fat/bone indices.Keywords: Live weight, chest girth, dressing out percentage, carcass composition

Potential of lactoperoxidase to diagnose subclinical mastitis in goats

This study was conducted to determine the potential of lactoperoxidase (LP) for the diagnosis of subclinical mastitis in goats. The activities of LP and somatic cell counts (SCC) were determined in the milk of clinically healthy Saanen and South African Indigenous goats and the correlation between LP activity and SCC was measured. An increase in LP activity was observed with increasing number of somatic cells in the milk of the two goat breeds. A significantly ( p < 0.01) positive correlation was observed between LP activity and SCC in the Indigenous ( r = 0.91) and Saanen ( r = 0.95) goat milk samples. The mean SCCs in Indigenous and Saanen goat milk samples were 2.5 × 10 4 and 2.0 × 10 6 cells/ml, respectively. The LP activity of Saanen goat milk ranged from 0.49 to 1.07 units/ml with a mean value of 0.80 units/ml. In the Indigenous goat milk, the LP activity ranged from 0.03 to 0.38 units/ml with a mean value of 0.26 units/ml. The positive correlation observed between SCC and LP activity suggests that LP may be used to detect subclinical mastitis in dairy goats.

Reproductive performance of South African indigenous goats following oestrous synchronisation and AI

The reproductive performance following oestrous synchronisation and artificial insemination (AI) was evaluated during the natural breeding season (autumn) in 90 indigenous (Boer and Nguni) South African goats. All does were synchronised for 16 days with medroxyprogesterone acetate (MAP) followed by an IM injection of 300 IU PMSG at progestagen withdrawal. Cervical inseminations were performed at a fixed time (48 h and 60 h) with fresh diluted Boer goat semen. No significant differences between Boer and Nguni goats were recorded with respect to oestrous response (98% and 93%) and the onset of oestrus (29.1 ± 0.9 h and 30.7 ± 0.8 h), respectively. The duration of oestrus in the Nguni goats (29.9 ± 2.0 h) was significantly ( P < 0.01) shorter than in Boer goats (37.0 ± 2.1 h). Conception rates were 52% and 53%, litter size averaged 2.2 ± 0.2 and 2.0 ± 0.2 and the gestation period an average of 148.6 ± 0.9 days and 149.1 ± 0.8 days for Boer and Nguni goats, respectively, these differences being non-significant. Does with quadruplets had a significantly ( P < 0.05) shorter gestation length (142.7 ± 2.1 days) than does with singles, twins and triplets (150.0 ± 0.9 days, 148.8 ± 1.0 days and 150.0 ± 1.1 days, respectively). The mean kid birth weight was 2.7 ± 0.5 kg with males being (2.8 ± 0.1 kg) significantly ( P < 0.05) heavier than females (2.5 ± 0.1 kg) and crossbred kids (2.9 ± 0.1 kg) significantly ( P < 0.01) heavier than pure Boer goat kids (2.4 ± 0.1 kg). Kid birth weight decreased with an increase in litter size, resulting in all birth weights for singles, twins, triplets and quadruplets being significantly ( P < 0.01) different from each other (3.6 ± 0.4 kg, 3.1 ± 0.5 kg, 2.3 ± 0.6 kg and 1.6 ± 0.3 kg, respectively). The overall neonatal loss rate within 48 h postpartum was 22.2%, which increased significantly with an increase in litter size and was significantly ( P < 0.01) higher for Boer goats (34.2%) than for crossbred kids (12.7%). The results indicate that oestrous synchronisation with progestagen is efficient and the duration of the induced oestrus is shorter in Nguni does than in Boer goat does. The conception rates obtained following oestrous synchronisation and AI were, however, very low and this aspect needs more attention. Litter size reduces birth weight and survival rate of indigenous South African goat kids.

Antibacterial activity of the lactoperoxidase system against food-borne pathogens in Saanen and South African Indigenous goat milk

The effect of the lactoperoxidase (LP) system on the growth and survival of Escherichia coli, Staphylococcus aureus, Listeria monocytogenes and Brucella melitensis was determined in goat milk samples kept at 30 °C for 6 h. The LP system exhibited a bactericidal effect against L. monocytogenes and Br. melitensis both in Saanen and Indigenous goat milks. The LP system was bactericidal against S. aureus in Saanen goat milk and bacteriostatic against S. aureus in Indigenous goat milk. However, the LP system was bacteriostatic against E. coli both in Saanen and Indigenous goat milks. The results of this study suggest the potential of the LP system to control the growth of food-borne pathogens in goat milk.

Composition of colostrum and milk of South African indigenous Nguni goats grazing natural pasture and supplemented with concentrate

Samples of colostrum, early and late lactation milk from thirteen South African indigenous Nguni goats (SAING) were analysed for contents of total solids (TS), solids-not-fat (SNF), fat, protein, lactose, ash and energy. Relationships between colostrum or milk and some parameters such as litter size (LS), milk yield (MY) and does kidding weight (DKW) were determined. Fat, protein and lactose contents of colostrum were poorly correlated (P > 0.05) with LS. Of relationships between early lactation parameters considered, only the coefficient between MY and DKW was significant (r = 0.72, P < 0.001). Correlations between protein and lactose contents of late lactation milk and LS were not significant (P > 0.05). However, the milk fat content of late lactation milk was significantly correlated with LS (r = 0.23, P = 0.041). Means of TS, SNF, fat and energy contents decreased with increased lactation period while ash content increased as lactation advanced. Protein and lactose contents were at maximum in colostrum and early lactation milk, respectively. Fat and TS contents of colostrum, early and late lactation milk samples were positively and significantly (P < 0.05) correlated. Fat content of colostrum and milk of SAING can be used to predict the dry matter (total solids) constituent of the goats' colostrum and milk.

Meat quality of designated South African indigenous goat and sheep breeds

Carcass composition, proximate meat composition, fatty acid composition and sensory characteristics of two breeds of goats, Indigenous ( n=12) and Boer goats ( n=12), and two breeds of sheep, Damara ( n=12) and Dorper ( n=12), on extensive pasture-grazing, were analysed. The right side of each carcass was processed into wholesale cuts and dissected into subcutaneous fat, meat and bone. Meat and fat were minced together and sampled for proximate analysis as well as fatty acid profiles. The remaining minced meat was formed into meat patties, which were cooked for descriptive sensory evaluation of aroma, tenderness, juiciness and flavour characteristics by a trained panel. Goat and sheep breeds had different meat qualities. The composition and properties of subcutaneous and intramuscular fat contributed to the differences in meat quality observed within and between the species studied. Goats had proportionally smaller carcasses. Sheep yielded more dissectable fat and lean and less bone as a percentage of carcass weight than goat breeds, although the proportional lean content per cut of Boer goats was comparable to that of sheep. The percentage of bone was highest for Indigenous goats. Concentrations of saturated fatty acids were higher in goats compared to sheep. Sheep patties were more tender, juicy, greasy and less chewy compared to goat patties. The species related goaty and muttony flavour were clearly distinguishable. It is recommended that goats should be valued as a different species compared to sheep.

Field activities and blood profile of pregnant South African indigenous goats after receiving dihydroxy pyridone-degrading rumen bacteria and grazing Leucaena leucocephala-grass or natural pastures

Twenty-four multiparous female South African indigenous goats were used. Once a week during the 2nd (weeks 8, 11 and 14) and 3rd (weeks 18, 19 and 20) trimesters, between 08·00 and 15·00 h, four females per treatment were randomly selected and observed every 1 min for time spent grazing, browsing, ruminating and idling. Blood samples were taken once a week during the 2nd (weeks 8, 11 and 14) and 3rd (weeks 18, 19, 20 and 21) trimesters for measurements of some mineral elements and protein metabolites. Goats on natural pasture (NP) grazed 54·8 min (P&lt;0·001) more and browsed 53 min (P&lt;0·001) less than goats on Leucaena leucocephala-grass pasture (LGP) during the 2nd trimester. During the 3rd trimester, goats on NP treatments grazed and idled more (24·7 min, P = 0·004; 15·8 min, P = 0·044, respectively) but ruminated less (−24·1 min, P&lt;0·001) than LGP goats. Time allotted to each field activity by the goats on both treatments within trimester seemed to be dependent on forage species composition while activity between trimesters was possibly influenced by seasons, plant type, herbage quantity, environment and quality, and changes in stage of gestation of the goats. Blood Mg level on NP was higher (P = 0·051) than on LGP during the 2nd trimester while blood Cu and albumin contents on LGP were significantly higher (P = 0·029 and 0·022, respectively) than on NP during the 3rd trimester. Furthermore, blood concentrations of the haematological parameters (except serum protein) on both treatments were within the normal range for goats in the tropics and subtropics and perhaps explain the absence of mineral and nutrient deficiency symptoms. The absence of visible symptoms of mineral deficiency and mimosine toxicity in LGP goats can be attributed to the transfer of DHP-degrading rumen bacteria. The bacteria effectively detoxified mimosine and its metabolites, thereby overcoming chelating tendency of mimosine and its metabolites. Mimosine-susceptible pregnant SAIG can be safely grazed on LGP once their rumen is completely colonized by the DHP-degrading rumen bacteria (Synergistes jonesii).

Reproductive performance of South African indigenous goats inoculated with DHP-degrading rumen bacteria and maintained on Leucaena leucocephala/grass mixture and natural pasture

This study examined the reproductive performance of dihydroxy pyridone (DHP)-inoculated South African indigenous (SAIG) female goats maintained on two dietary treatments: (i) Leucaena leucocephala/grass mixture and (ii) natural pasture prior to conception, and during gestation. Leucaena leucocephala/grass mixture was nutritionally superior (crude protein and mineral elements) than the natural pasture. The average daily gain, products of pregnancy and foetal development in gravid goats raised on leucaena/grass mixture were significantly ( P<0.03, P<0.009 and P<0.005, respectively) higher than those raised on natural pasture. Conception rate of goats fed natural pasture was higher than the band fed Leucaena leucocephala/grass mixture. Leucaena/grass mixture fed goats had kids that were heavier at birth than their counterparts on natural pasture. Pre-weaning kid mortality over the period of study was significantly ( P<0.01) higher in the Leucaena leucocephala/grass mixture treatment. Colostrum from kidded goats fed leucaena was viscous and difficult to sample. The absence of mimosine toxicity symptoms suggests a possibility of safe use of leucaena as a feed resource to DHP-inoculated SAIG.

The reproductive performance of South African indigenous goats grazing Leucaena leucocephala pasture and natural veld during gestation

The widely distributed South African indigenous goat (SAIG) is reared under extensive systems (Duvel & Afful, 1994) characterised by low production rates resulting from nutritional constraints. Leucaena species grow well in the absence of nitrogenous fertilizer and are rich in protein (14-30% CP) and minerals ( Nsahlai et al., 1994). Incorporation of Leucaena cultivation into these farming systems will not only improve soil fertility but alleviate nutritional constraints for ruminants. Substantial benefits were reported on intake, digestibility and growth of ruminants fed Leucaena ( Morris & du Toit, 1998) but there were no reports on the forage carry-over effects.