Browsing by Author "Pereka, A. E."

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Effect of ambient temperature on daily milk yield and blood flow to the mammary gland in lactating goats treated with growth hormone
(Tanzania Veterinary Journal, 1990) Pereka, A. E.
The study was done with the objective of studying the effect or high temperature on the mammary gland production in terms or its blood supply and synthetic capacity. Growth hormone was injected to see whether high temperature has an interaction with the galactopoietic effects of the hormone in the mammary gland. Eight, one year old goats in their 6th week of lactation (1st lactation) were put into two climatic chambers, four in a chamber at 12°C and four in a chamber at 30°C. After four weeks of exposure to their respective temperatures two goats in each chamber were injected with bovine somatotropin (BST) daily for fifteen days. Daily milk yield was recorded. Blood flow rate was calculated from velocities measured using the Doppler Ultrasound Technique. Milk yield in goats at 30°C was 78% of milk yield of goats at 12°C at all times. With BST treatment milk yield increased by 9% and 13% at 12°C and 30°C respectively. Blood flow rate (L/day) to the mammary gland was in accordance to the milk yield with a blood flow rate: milk yield (CBF MY) ratio of 572 ± 166: 1 and 760 ± 180 : 1 at 12°C and 30°C respectively. With BST treatment the BF:MY ratio was 1059 ± 263 : 1 and 89 ± 38: 1 at 12°C and 30°C respectively. It is herewith concluded that blood flow to the mammary gland is a factor contributing to increased milk yield as it supplies the necessary nutrients for milk synthesis in the udder. The depressive effects of high ambient temperature can be counteracted by BST treatment as this increases milk yield not only through increased blood flow but also increased efficient nutrient extraction and utilization by the mammary gland cells for milk synthesis
Hepatic blood flow rate, plasma triglycerides and free fatty acids flow in pregnant sheep during fasted and feeding state
(Tanzania Veterinary Journal, 1992-08) Pereka, A. E.
Hepatic blood flow rates were measured in both pregnant and non-pregnant sheep using the marker dilution technique with creatinine as the marker substance. Hepatic blood flow rates were slightly higher in pregnant than in non-pregnant sheep at all times. The effect of fasting/feeding on the flow rates was the same in both pregnant and non-pregnant sheep. Plasma triglycerides (TG) and free fatty acids (FFA) were measured. The concentrations were used to calculate their flow rates from the portal drained tissues and liver uptake. Fasting increased the plasma FFA levels more so in pregnant sheep, while feeding decreased the levels. Similarly TG levels were higher in pregnant sheep than in non-pregnant sheep (as seen in Table 3). It was concluded that fasting is a stress which reduces the energy supply for the animal. The physiological status of the animal such as pregnancy exaggerates the effects thereby the energy demand increases.
Mineral content in soils and pasture grasses at ASAS farm, Iringa, Tanzania
(Tanzania Veterinary Journal, 1998) Pereka, A. E.; Phiri, E. C. J. H.
The assessment of mineral content in soil and pasture grasses was carried out in Iringa Tanzania to establish the existence of any particular mineral deficiency or excess on the farm. The following levels of soil minerals, sodium (Na): 2.28% and 3.3Q%; potassium (K): 0.47% and 0.36%; calcium (Ca): 2.26% and 5.2%; magnesium (Mg): 0.61% and 1.41%; manganese (Mn): 56.8 and 42.6 ppm; copper (Cu): 1.63 and 2.19 ppm and iron (Fe): 130 and 120 ppm were observed during the dry and wet season respectively. These were considered to be adequate sources for grazing animals. Soil zinc (Zn) was marginal in dry season (1.25 ppm) but was below critical levels (0.23 ppm) in wet season. In case of pasture grasses the following minerals were adequate in dry and wet season respectively, potassium (K) (0.67% and 1.89%); Na (0.13% and 0.35%); Ca (0.38% and 0.64%); Mn (93.7 and 87.8 ppm) and Fe (400 and 450 ppm). Whereas Cu (6.8 and 7.6 ppm), Zn (19.2 and 23.8 ppm) and Mg (0.15% and 0.17%) were below critical levels in dry and wet season respectively. Pasture phosphorous (P) was below critical levels (0.18%) in wet season but high in dry season (0.31%). The concentration of minerals in the soil did not correspond well with the mineral concentration in pastures. It was recommended to analyse the mineral concentrations in the animal tissues to ascertain the mineral status in the farm so as to establish a strategy for mineral supplementation
The effect of feeding on: I hepatic plasma flow in adult non-pregnant sheep
(Tanzania Veterinary Journal, 1992-08) Pereka, A. E.
Work was done on adult sheep to determine the effect of feeding perse on hepatic plasma flow. Continuous infusion of creatinine was used to determine the flow rate. Feeding increased hepatic plasma flow with maximum peak reached at 2-4 hours post-feeding. An increase of 53% and 27% of total hepatic plasma flow (THPF) and portal venous flow (PVF) respectively over the pre-feeding values was observed. In conclusion feeding is a stimulus on its own for increased hepatic-portal plasma flow.
The effect of feeding on: II plasma triglycerides flow and uptake by the liver in normal adult sheep
(Tanzania Veterinary Journal, 1992-08) Pereka, A. E.
Plasma triglycerides (TG) were measured in portal hepatic veins and arterial blood before, during and after feeding grass hay. In order to determine the liver uptake or output portal blood flows were measured by a continuous creatinine infusion method. Arterial plasma TG concentration in fasted and fed adult sheep was 0.204±0.02 and 0.282±0.02 mmole/L respectively while the venous plasma TG was 0.151+0.01 and 0.184+0.02 mmole/L respectively. No apparent change in plasma TG concentration was noted when sheep were fed. Post feeding TG release from the splanchnic tissues was 0.006±0.001 mmole/min.kg 0.73 as opposed to 0.004±0.002 mmole/min. kg 0.73 during the fasted state. During feeding and for a few hours (2-4) post-feeding the hepatic TG uptake was 0.009±0.004 mmole/min. kg 0.73 in contrast to 0.006±0.002 mmole/min. kg 0.73 during fasted state
The effect of mineral glass boluses supplementation on plasma copper, ceruloplasmin, glutathione peroxidase and other parameters in grazing heifers
(Tanzania Veterinary Journal, 1998) Pereka, A. E.; Phiri, E. C. J.
The effect of supplementation of slow releasing intra - ruminal mineral glass boluses containing 13.4% copper (Cu) as CuO w/ v, 0.3% selenium (Se) as Na2Se04 and 0.5% cobalt (Co) as Co03 4 w/w on plasma Cu, ceruloplasmin (CP) and glutathione peroxidase (GSH.Px) activities, body weight gain (LBW), packed cell volume (PCV) and haemoglobin (Hb) was assessed in grazing heifers for eight months. Heifers were weighed and PCV, Hb, plasma Cu, CP, GSH.Px measured before supplementation started and thereafter every two months. There were no significant statistical differences (P< 0.05) between control and supplemented heifers in terms of PCV (30.3% vs 31.0%), Hb (11.4 vs 11.8 g/100 ml), plasma Cu (0.93 vs 0.91 mg/1) and CP (55 vs 54 U/ 1). However, significant statistical differences (P< 0.05) were observed on live body weight (LBW) (236 vs 248 kg), and GSH.Px activity (384 vs 462 U/ gHb). It was concluded that the intra - ruminal glass boluses were not as effective in providing immediate boost to Cu reserves in the body as anticipated but were sufficient in releasing significant quantities of Selenium
Urban livestock farming in Tanzania: causes, effects and future prospects authors
(Tanzania Veterinary Journal, 2004) Mlay, P. S.; Pereka, A. E.
Urban livestock farming in Tanzania has seen a tremendous rise since the late seventies. Several factors acting singly or concurrently led to the trend we are observing today. The major driving forces are social economic, cultural and to some degree political in nature. It is commonly agreed that there are some positive and negative effects of urban livestock farming. This paper intends to give a fair discussion and analysis of the issues behind the -rapid growth of urban livestock farming (ULF) with emphasis on dairy as the most practised type of ULF. As matters stand now, urban livestock farming will continue to play a major role in the provision of the greatly needed animal products by the ever-increasing urban population. It will be selfcheating to think that we can abolish ULF by the present laws and bylaws that are hard if not impossible to implement. Therefore, there is a need of a change in attitude by the responsible authorities to recognise ULF as a fact of life and find ways of minimising the negative effects through positive engagement with all stake-holders