The Use of Faecal Progestin Measurements to Monitor Reproductive Activity in Mashona Cows in a Smallholder Farming Area of Zimbabwe

The objectives of this study were to investigate the relationship between the concentrations of progesterone (P₄) in the peripheral circulation and progestins in the faeces of cows in a smallholder farming area and to monitor the ovarian activity of such cows. The study was carried out in Sanyati smallholder farming area, located 250 km southwest of Harare. Blood and faecal samples for P₄ and progestin determination, respectively, were obtained once a week from 35 Mashona type cows that belonged to farmers from three different villages. The cows were weighed once every month and all births were recorded. The concentrations of progestins in faeces and P₄ in plasma were positively correlated (r = 0.72, p<0.01). Most of the non-pregnant cows (65%) cycled during the rainy season. Most of those that were acyclic at this time were undergoing post-partum anoestrus. During the dry season, most cows (58%) became acyclic as forage became scarce and of poor quality. Thirty-two calves were born during the study period, mostly during the first or last two months of the year, when there was enough forage. The mean calving to first oestrus in 14 cows that recalved was 71±49 days. Eight of these 14 cows conceived again, the calving to conception interval being 173±94 days. The cows' liveweights were highest in April, at the end of the rainy season. By the end of the dry season, the cows had lost, on average, 15% of their peak weight.     

Effects of Supplementing a Basal Diet of Chloris gayana Hay with One of Three Protein-rich Legume Hays of Cassia rotundifolia,Lablab purpureus and Macroptilium atropurpureum Forage on Some Nutritional Parameters in Goats

Growth and digestibility experiments were conducted on growing East African type goats offered Chloris gayana hay supplemented with one of three high-protein (119–128 g CP/kg DM) legume hays, Cassia rotundifolia (cassia), Lablab purpureus (lablab) or Macroptilium atropurpureum (siratro), and crushed maize to investigate the feed intake, digestibility, growth and urinary excretion of purine derivatives. Goats in the supplemented groups had higher total dry matter and nitrogen intakes and higher N retention and body mass gains than unsupplemented counterparts. The digestibility of dry matter, organic matter and neutral detergent fibre were increased by protein supplementation. Animals on supplemented diets had higher fractional outflow rates of particulate matter from the rumen. The production of protein by ruminal microbes and the efficiency of microbial N production were increased by supplementation. It was concluded that a mixture of low-quality grass hay (61.9 CP/kg DM) and either cassia, lablab or siratro hay, and maize grain can provide a productive balanced diet for growing goats.     

Effects of breed and feed supplementation on the fertility of cows developed for milk production in Zimbabwe

Forty-six indigenous Sanga-type (Nkone and Tuli breeds) cows and 46 crossbred (Nkone x Jersey and Tuli x Jersey) cows were randomly allocated to four treatment combinations in a 2 x 2 factorial arrangement with two breeds and two dietary levels, a control diet and a diet supplemented with dairy meal containing 14 per cent crude protein at the rate of 2 kg per cow per day. The progesterone concentration was measured in milk samples taken three times a week from 10 days postpartum for up to 200 days, and the cows' bodyweights and body condition scores were recorded fortnightly. The pregnancy rate in the crossbred cows was significantly higher (P<0.05) than in the indigenous cows, and the assumed pregnancy loss rate 30 days after conception was significantly higher (P<0.05) in the indigenous cows than in the crossbred cows. The supplemented crossbred cows had a lower pregnancy loss rate than the supplemented indigenous cows (P<0.05). All the supplemented indigenous cows that lost pregnancies were in their first parity, whereas all the crossbred cows that lost pregnancies were multiparous and were not supplemented. The indigenous cows weighed significantly more (P<0.05) than the crossbred cows irrespective of diet, and the supplemented cows of both breeds weighed more (P<0.05) than the control cows. The supplemented indigenous cows had significantly higher (P<0.05) body condition scores than the control cows. The mean dairy milk yield of all the breeds was generally low but significantly higher (P<0.05) in the crossbred than in the indigenous cows.     

The Concentration of Faecal Progestins during the Oestrous Cycle in Nkone Cows and the Effect of Duration of Storage of Faecal Samples at Room Temperature on Faecal Progestin Levels

The objectives of this study were to determine whether ovarian function in Nkone cows could be monitored by measuring progestin concentrations in faeces and to assess the effect of duration of storage at room temperature on faecal progestin concentrations. Faecal and blood samples were obtained once a day for 26 days from 21 Nkone cows whose oestrous cycles had been synchronized. Faecal samples from each cow were divided into five portions that were kept at room temperature for 0, 6, 12, 24 and 48 h, respectively, and then frozen. After centrifuging the blood to recover plasma and extracting steroids from the faeces, analysis of progesterone (P₄) was carried out using solid-phase radioimmunoassay. The faecal progestin and plasma progesterone profiles corresponded well and were positively correlated (r = 0.70, p>0.01). Faecal progestin concentrations decreased with increasing duration of storage at room temperature during both the follicular and luteal phases (p>0.01). In both cases, the decline in faecal progestin concentrations followed an exponential pattern. The progestin concentrations in faeces after 48 h of storage at room temperature were higher (p>0.05) during the peak luteal phase than in the follicular phase.     

Evaluation of Synchronization of Oestrus Based on Gonadotrophin-releasing Hormone and Its Potential Use for Fixed-Time Breeding in Tuli Beef Cows

The objective of the experiment was to compare the reproductive post-partum performance of beef cows synchronized for oestrus using prostaglandin F₂ (PGF₂) alone or with a gonadotrophin-releasing hormone (GnRH)-based drug. Fifty-five post-partum lactating Tuli cows were randomly allocated to three groups. Two groups were synchronized using either two injections of PGF₂ (500 g Prosolvin per injection) given 11 days apart (group 1), or GnRH (12.5 g Receptal per injection) followed 6 days later by an injection of 500 g PGF₂ (group 2). The cows were bred by artificial insemination 12 h after they were observed in oestrus. Group 3 was synchronized as for group 2, but a second injection of GnRH was given 54 h after the PGF₂ injection, at which time the cows were bred by artificial insemination (AI) without detection of oestrus. Blood samples were taken from the cows in group 3 and analysed for progesterone concentration to establish which cows were cycling and in oestrus before and at the time of breeding. Detection of oestrus and breeding by AI was done over 60 days. There were no significant differences (p>0.05) among the three groups in the first service and total conception rates. The percentage of cows in oestrus within 10 days of the synchronization treatment was not significantly different (p>0.05) between groups 1 and 2. The progesterone concentrations in the cows in group 3 showed that only those that were cycling at the start of the experiment responded to the synchronization treatment and conceived after fixed-time breeding. These results suggest that combinations of PGF₂ and GnRH may be of value in synchronizing oestrus and controlling breeding in Tuli cows. However, the benefit might be greater if only cows that are known to be cycling are bred in this way.     

Acaricidal efficacy against cattle ticks and acute oral toxicity of Lippia javanica (Burm F.) Spreng

Tropical Animal Health and Production - In search for low-cost, safe and environmentally benign plant-based alternatives to commercial pesticides, the efficacy of Lippia javanica aqueous leaf...     

Efficacy of Strychnos spinosa (Lam.) and Solanum incanum L. aqueous fruit extracts against cattle ticks

The efficacy of Solanum incanum and Strychnos spinosa aqueous fruit extracts was evaluated against cattle ticks in on-station experiments and laboratory tick bioassays. In the on-station experiment using cattle, fruit extracts were applied at three concentrations 5, 10, and 20 % (w/v) and compared with a commercial acaricide, Tickbuster® (amitraz) spray (positive control) and no treatment (negative control). The treatments were applied at weekly intervals for 6 weeks as surface sprays on 32 Mashona cattle in a completely randomized design experiment. Ticks on individual cattle were identified, counted, and recorded daily. Peripheral blood samples were collected for parasite screening. In the laboratory, tick bioassays were conducted at four concentrations, 5, 10, 20, and 40 % (w/v) fruit extracts compared to Tickbuster® (amitraz) spray (positive control) and distilled water (negative control). The extracts were incubated with Rhipicephalus (Boophilus) decoloratus tick larvae and mortalities for each treatment level recorded after 24 and 48 h. The 5 % Solanum incanum treatment had higher efficacy ratio (P?<?0.05) than the other fruit extract concentrations of the same plant species. Efficacy ratio was higher (P?<?0.05) in the 5 % S. spinosa-treated cattle than in the untreated control but lower (P?<?0.05) than that for the amitraz treatment. The bioassays indicated that there was a high efficacy ratio for the lowest fruit extract concentrations when ticks were exposed to acaricidal treatments for 48 h compared to 24 h. Overall, the results indicate that Solanum incanum and Strychnos spinosa individually have some acaricidal effect.     

The effect feeding forage legumes as nitrogen supplement on growth performance of sheep

The effect of feeding forage legumes, Cowpea, Silverleaf desmodium and Oxley fine stem stylo, as protein supplements to natural pasture (veld) hay on intake, growth rate and nitrogen metabolism in growing lambs was evaluated. Thirty growing lambs were stratified according to body weight and randomly assigned, within a stratum, to five diets in a completely randomised design. The diets were veld hay alone (V), veld hay supplemented with either 10 g/kg of urea (VU), veld hay supplemented with 250 g/kg Cowpea (VC), 250 g/kg Silverleaf desmodium (VS) or 250 g/kg Oxley fine stem stylo (VF) forage legume hays. The V and the VU groups were used as control diets. Animals supplemented with either urea or the forage legume had higher (P < 0.01) total dry matter intake compared with the animals on V. The animals supplemented with the forage legumes had higher (P < 0.01) nitrogen intake and faecal nitrogen output than the non-supplemented group. All animals, across the treatments, lost body weight; lambs on V had higher (P < 0.01) body weight losses than those in the other treatments. The forage legume supplemented groups lost less (P < 0.01) body weight than those on the V and VU diets. Although supplementation with forage legumes enhanced feed intake and reduced weight losses it did not maintain body weights of lambs fed a basal diet of poor quality roughages.     

Reproductive Performance and Body Weight Changes in Draught Cows in a Smallholder Semi-arid Farming Area of Zimbabwe

The reproductive performance of 46 cows in a semi-arid, smallholder farming area of Zimbabwe was monitored for a year. Half the cows were used throughout the monitoring period for various draught purposes, including ploughing and procurement of farm produce for marketing using carts. All the cows lost body weight between July and October, after which the cows that were not worked gained weight until June of the following year. In contrast, the cows that were worked continued to lose body weight until January, throughout the time during which they were used to provide draught power, after which they gained weight. Body weights were significantly higher (p<0.05) in non-working than in working cows in January and February. Ovarian activity was higher (p<0.001) in non-working compared to working cows, particularly between November and February, while calving rates were also higher (p<0.05) in non-working cows. It is concluded that using cows for draught purposes caused loss of body weight and reduced ovarian activity and conception rates.     

A Monitoring Study on the Prevalence of Dermatophilosis and Parafilariosis in Cattle in a Smallholder Semi-arid Farming Area in Zimbabwe

The prevalences of dermatophilosis and parafilariosis were monitored for one year in cattle in Sanyati, a semi-arid smallholder farming area in Zimbabwe. The prevalence of dermatophilosis differed (p < 0.05) with season and among calves, cows, oxen and bulls. In bulls and cows, dermatophilosis lesions were localized mainly to the inguinal regions and between the front limbs. The prevalence and morbidity of dermatophilosis infection were significantly higher (p < 0.05) during the wet season than in the dry season. No mortalities were recorded. The prevalence of parafilariosis was similar to that of dermatophilosis. Infection of cattle by these skin diseases was preceded by high infestation with the tick Amblyomma variegatum. The results suggest that dermatophilosis and parafilariosis have become major diseases that could compromise reproductive performance, draught power availability and overall cattle productivity, particularly during the rainy season in Sanyati smallholder farming area of Zimbabwe.