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Articles by J.W. Ng`ambi
Total Records ( 16 ) for J.W. Ng`ambi
  O.J. Alabi , J.W. Ng`ambi , D. Norris and S.S.A. Egena
  The aim of this study was to undertake a comparative evaluation of the body weight and linear body measurements of three indigenous chicken breeds of South Africa, namely: Naked neck, Venda and Potchefstroom koekoek. A total of 222 records obtained from the three intensively reared breeds were used in the study. Data were collected at the experimental farm of the University of Limpopo, South Africa. Treatment means were separated using t-test and analysis of variance with the level of significance set at 5%. Body weight was correlated with the linear body measurements. The parameters evaluated were: Body Weight: BW, Body Length: BL, Body Girth: BG, Wing Length: WL, Shank Thickness: ST and Shank Length: SL. The measurements were taken at maturity (22 weeks of age). Results showed that males of the three breeds were statistically (p<0.05) heavier had longer body, better body girth, wing length, shank thickness and shank length than the females. Comparison of the three breeds also revealed that Potchefstroom koekoek chicken was significantly (p<0.05) better than the Naked neck and Venda chickens for the traits evaluated with the exception of shank length where no significant (p>0.05) differences were observed between the three breeds. No differences (p>0.05) were observed between the Naked neck and Venda chickens for body weight, body girth and shank thickness. BW was best correlated with SL (Naked neck; r = 0.92), ST (Venda; r = 0.80) and ST (Potchefstroom koekoek; r = 0.80). BW was best predicted using SL (Naked neck; -0.5129+0.0825SL), ST (Venda; -0.1381+ 0.4515ST) and ST (Potchefstroom koekoek; -0.2004+0.4621ST). It was concluded that breed differences do exist between the three indigenous South African chicken breeds studied and these differences are in favour of the males and the Potchefstroom koekoek chickens.
  C.A. Mbajiorgu , J.W. Ng`ambi and D.D. Norris
  The phenomenon of feed intake response trends to differing feed energy and protein levels is reviewed. Increased interest in this concept is attributed to problems associated with maintaining adequate feed intake in many farms. This becomes an important factor limiting productivity. Though the spectrum of factors that affect voluntary feed intake in poultry is very broad, it is important to highlight the influence of dietary factors, particularly, energy and protein densities on voluntary feed intake responses in chickens. In formulating poultry diets, the nutrient requirements of broiler chickens have frequently been expressed per unit of dietary metabolizable energy. This practice is based on the theory that birds will adjust their feed intake according to their metabolisable energy requirements. However, based on a re-evaluation of numerous research data, the application of specific nutrient-to-metabolisable energy ratios in broiler chickens becomes questionable. Many studies have shown that feed intake responses in chickens offered diets differing in feed energy and protein levels are influenced by the level of the first limiting nutrient in the feed rather than the feed energy level per se. This observation on limitations in feed intake, in effect, challenges the strongly held theory that all chickens will consume diets to meet their energy requirements and thereby achieve their genetic potential for growth. Thus, because of the important implications of these differences, both the energy and protein levels of the diet should be taken into account when formulating diets aimed at achieving optimal feed intake in growing chickens.
  C.A. Mbajiorgu , J.W. Ng`ambi and D. Norris
  Two experiments were conducted to determine the effect of varying dietary energy to protein ratio on growth and productivity of indigenous Venda chickens raised in closed confinement from day-old up to 13 weeks old. In each experiment the diets had a similar energy value of 12.2 MJ ME kg-1 DM, but with five different levels of protein concentration of 220, 190, 180, 170 and 160 g kg-1 DM, thus ending up with different energy to protein ratios of 55, 64, 68, 72 and 76 MJ ME kg-1 protein. A complete randomized design was used in each experiment, the one to six weeks old growing period (unsexed Venda chickens) and the seven to 13 weeks old growing period (male Venda chickens) experiments. A quadratic type equation was used to determine the ratios for optimum production variable. A single E:P ratio of 62 MJ ME kg-1 protein supported optimum feed intake and growth rate while an E:P ratio of 63 MJ ME/kg protein supported optimum feed conversion ratio in Venda chickens aged between one and six weeks. In contrast, an E:P ratio of 60 MJ ME kg-1 protein supported optimum growth rate and feed conversion ratio in male Venda chickens aged between seven and 13 weeks. However, an E:P ratio of 62 MJ ME kg-1 protein supported optimum feed intake in male Venda chickens aged seven to 13 weeks. The results indicate that a single E:P ratio of 62 MJ ME kg-1 protein optimized feed intake in Venda chickens irrespective of differences in sex and age. These findings have implications on ration formulation for Venda chickens.
  C.A. Mbajiorgu , J.W. Ng`ambi , D. Norris and O.J. Alabi
  Two experiments were conducted with the aim of determining the effect of dietary lysine to energy ratio on performance of unsexed indigenous Venda chickens raised in closed confinement from day-old up to 13 weeks old. In each experiment the diets were isocaloric and isonitrogenous but with different lysine to energy ratios. A complete randomized design was used in both experiments, the starter (1-6 weeks) and grower (7-13 weeks) experiments. The three starter diets, based on lysine to energy ratios, were T0 (0.84), T1 (1.04) and T2 (1.23) g MJ-1 ME, while grower diets were T3 (0.52), T4 (0.71) and T5 (0.89) g MJ-1 ME, respectively. A quadratic type equation was used to determine ratios for optimum growth, feed conversion ratio, breast meat yield and breast meat nitrogen content. The results indicate that at each phase different dietary lysine to energy ratios optimized both growth rate and feed conversion ratio. Dietary lysine to energy ratios of 1.20 and 1.17 g MJ-1 ME supported optimum growth rate and feed conversion ratio, respectively, during the starter period. Dietary lysine to energy ratios of 0.76 and 0.84 g MJ-1 ME supported optimum growth rate and breast meat nitrogen content during the grower phase. However, a single ratio of 0.81 g MJ-1 ME supported optimum breast meat yield and optimum feed conversion ratio. Dietary lysine to energy ratio had no effect on diet intake, digestibility and carcass weight. These findings have implications on ration formulation for indigenous Venda chickens.
  K.E. Ravhuhali , J.W. Ng`ambi , D. Norris and V.I. Ayodele
  The study was carried out to determine the effect of cowpea cultivar supplementation on intake, digestibility and live weight changes of Pedi goats fed ad libitum buffalo grass hay. This involved five experiments. Experiments 1.1 to 1.4 involved Pan 311, Red caloona, Black eye and Agripeas cowpea cultivars, respectively, while Experiment 1.5 compared the levels of supplementation for optimum intake from each of the first four experiments. Twelve growing male indigenous Pedi goats were used in each experiment. Each cowpea hay cultivar was given as a supplement at four levels (50, 100, 150 and 200 g day-1) to a diet of buffalo grass fed ad libitum to indigenous Pedi goats. A completely randomized design was used for all experiments. The experiments were run for 25 days of preliminary period plus 5 days of collection period. Feed intake, digestibility, live weight changes and nitrogen intake were measured. All the cowpea cultivars contained more than 15% crude protein. Pan 311 had higher (p<0.05) feeding values than the other cultivars. However, Pan 311 contained the highest amounts of condensed tannins. These high amounts of condensed tannins in Pan 311 did not exert negative effects on its intake and digestibility. Chemical composition values of the cowpea cultivars found in the present study are quite high and hence the legumes should be able to supply enough nutrients, particularly proteins, to ruminant animals when given as supplements.
  N.A. Sebola , J.W. Ng`ambi , D. Norris and C.A. Mbajiorgu
  Two experiments were conducted to evaluate the effects of Garcinia cambogia leaf meal supplementation levels at finisher stage on productivity and juiciness of male Ross 308 broiler chickens. The design of the experiments was a completely randomised design. The first experiment examined the effect of level of Garcinia cambogia leaf meal supplementation at finisher stage (29 to 42 days of age) on productivity and carcass characteristics of male Ross 308 broiler chickens. Level of Garcinia cambogia leaf supplementation had no effect (p>0.05) on feed intake, growth rate, feed conversion ratio, live weight, blood glucose, blood urea and carcass characteristics of male broiler chickens. However, daily supplementation with 300 mg of Garcinia cambogia leaf meal per kg DM feed reduced (p<0.05) fat pad weight by 18.75% in broiler chickens. This could not be explained in terms of differences in feed intake, digestibility, or growth rate. The second experiment examined the effect of Garcinia cambogia leaf meal supplementation interval on juiciness of Ross 308 broiler chickens. Garcinia cambogia leaf meal supplementation interval had no effect (p>0.05) on meat flavour of male Ross 308 broiler chicken meat. However, daily supplementation with 300 mg of Garcinia cambogia leaf meal reduced (p<0.05) juiciness of male Ross 308 broiler chicken meat by 40%.
  M. Mabelebele , J.W. Ng`ambi and D. Norris
  An experiment was conducted to determine the effect of dietary Vitamin D3 supplementation on sensory attributes (meat tenderness, juiciness and flavour) of indigenous Venda cock meat. Different supplementation levels (0, 2000, 4000, 6000 and 8000 IU) of dietary Vitamin D3 per kg DM (880 g kg-1 feed) feed were used. In this experiment, thirteen weeks old Venda cocks with a mean live weight of 1200±3 g were supplemented with the above different levels of Vitamin D3 for a period of seven days before slaughter. A 2 (postmortem aging of 0 or 24 h) x5 (dietary Vitamin D3 levels) factorial arrangement in a complete randomized design was used for sensory evaluation of the meat. A quadratic equation was also used to determine Vitamin D3 supplementation levels for optimum meat tenderness, juiciness and flavour. Vitamin D3 supplementation had no effect on unaged meat tenderness, juiciness and flavour. However, Vitamin D3 supplementation improved (p<0.05) aged meat tenderness and flavour. Tenderness, juiciness and flavour of aged Venda cock meat were optimized at supplementation levels of 6830, 6894 and 9795 IU of Vitamin D3 per kg DM feed, respectively. It is concluded that Vitamin D3 supplementation improved tenderness and flavour of aged Venda cock meat.
  O.J. Alabi , J.W. Ng`ambi and D. Norris
  Egg weight is an important parameter that influences hatchability. This study was conducted to determine the effect of egg weight on egg weight loss, fertility, embryonic mortality, hatching yield and hatchability of indigenous Venda chickens (Gallus gallusdomesticus). A total of 690 Venda chicken eggs obtained from the Agricultural Research Council, Pretoria, South Africa were classified according to three weight groups (A:>50 g, B: 45-50 g and C:<45 g). A complete randomized design of three Treatments, five replicates and each replicate having 46 eggs was used for the experiment. Egg weight loss, embryonic mortalities (total, early, medium and late), hatching yield and hatchability were significantly (p<0.001) affected. However, no differences were detected in the fertility of total egg and egg fertility rate. The medium size eggs (group B) had the least mortality (18.11%), the highest hatching yield (76.39%) and hatchability (81.89%). This may imply that sorting indigenous Venda chickens' eggs prior to incubation might be advantageous in production operation aimed at improving the productivity of these chickens.
  O.J. Alabi , J.W. Ng`ambi , D. Norris and M. Mabelebele
  A study was conducted to determine the effect of Potchefstroom Koekoek chicken egg weight on hatchability and subsequent chick performance. In the first part of the study, a total of 450 Potchefstroom Koekoek eggs were used in a complete randomized design to determine the effect of egg weight on hatchability, embryonic deaths, egg weight loss and hatch weight. The eggs were allocated into three weight-treatments: large (>55 g, A), medium (45-55 g, B) and small (<45 g, C). Hatching yield, hatchability, embryonic deaths, egg weight loss and hatch weight were significantly (p<0.05) affected by the weight of the eggs. The large and medium-sized eggs had higher hatching yield (60 and 70%, respectively). The medium-sized eggs had higher (p<0.05) hatchability values than both small and large-sized eggs. Medium-sized eggs had lower (p<0.05) embryonic deaths (31%) than small (45%) and large (36%) egg sizes. The large-sized eggs had higher hatch-weights than small and medium-sized eggs. The total embryonic deaths, hatching yield and hatchability percentages were optimized within the medium-sized eggs (51 g, r2100). The second part of the study was aimed at determining the effect of Potchefstroom Koekoek egg weights on subsequent chick performance and carcass characteristics. The chicks were fed a growers diet containing 11.97 ME MJ kg-1 DM feed of energy and 161 g kg-1 CP. Feed and water were given ad libitum. All the performance parameters were significantly (p>0.05) influenced by egg weight except mortality of the chicks at both starter and finisher phases. The large-sized egg had high (p<0.05) weight gain, better (p<0.05) daily feed intake (36 and 94 g) and feed conversion ratio (3.0 and 5.1) for both starter and finisher phases, respectively. It can be concluded that for better hatchability medium-sized eggs can be considered. However, if growth performance is of primary importance large-sized eggs can be used.
  M. Mabelebele , O.J. Alabi , J.W. Ng`ambi , D. Norris and M.M. Ginindza
  A study was conducted to determine and compare the weights and lengths of the gastrointestinal organs and pH values in the digestive tracts of Ross 308 broiler and indigenous Venda chickens. A complete randomized design with two treatments (Ross 308 broiler and indigenous Venda chickens) having five replicates was used in this study. Chickens used in this study were aged 1 to 70 days. Weights, lengths and pH values of different segments of the gastrointestinal Tract (GIT) were measured. There were differences (p<0.05) between breeds in live weight, crop, gizzard and large intestine weights. However, proventriculus, small intestine and caecum weights were not influenced (p>0.05) by the breed differences. The gastrointestinal tracts of broiler chickens were longer (p<0.05) than those of indigenous Venda chickens. Proventriculus, large intestine and caecum pH values were not affected by breed differences. However, crop, gizzard and small intestine pH values for indigenous Venda chickens were lower (p>0.05) than those for broiler chickens. It is concluded that differences exist in the body weight, GIT and pH values between the indigenous Venda and broiler chickens. The lower pH values and the larger crops and gizzards observed in the indigenous chickens might be the reasons why this breed has the ability to digest fibrous feed better than the broiler chickens. Broiler chickens have lengthy digestive tracts than indigenous Venda chickens, which indicate a higher surface area for nutrient digestion and absorption.
  T. Gwanzura , J.W. Ng`ambi and D. Norris
  The nutrient composition and tannin contents of forage sorghum (Sorghum sudanese), cowpea (Vigna unguiculata), lablab (Lablab purpureus) and mucuna (Mucuna pruriens) were determined by chemical methods. The experimental design was a completely randomised design with four treatments: forage sorghum, cowpea, lablab and mucuna hays. All the legume species had higher (p<0.05) protein contents than sorghum hay, ranging from 18-22%. Within the legume species, cowpea hay had higher (p<0.05) protein content than lablab and mucuna hays. Similarly, lablab hay had higher (p<0.05) protein content than mucuna hay. Sorghum hay had higher (p<0.05) NDF and ADF values than the legume species. Mucuna hay had higher (p<0.05) concentrations of both condensed tannins and hydrolysable tannins than cowpea, lablab and sorghum hays, while lablab hay had the highest (p<0.05) concentrations of total polyphenols. Among the legume species, mucuna hay had higher (p<0.05) NDF and ADF values than lablab hay, while those of cowpea and lablab hays were similar (p>0.05). Legumes have the potential of being utilised as protein supplements for ruminants on low quality roughages. However, tannins in legumes may have both negative and positive effects on diet intake, digestibility and palatability. There is, therefore, need to evaluate these legumes when used as protein supplements for ruminants on a basal diet of sorghum hay.
  D.J. Novele , J.W. Ng`Ambi , D. Norris and C.A. Mbajiorgu
  The effects of sex, level and period of feed restriction during the starter period on productivity and carcass characteristics of Ross 308 broiler chickens were evaluated. A 2 (male and female chickens) x 3 (feeding levels: Ad-libitum, 75% and 50% of ad libitum) x 3 (restriction periods of 5, 7 and 9 days) factorial arrangement in a complete randomized design was used. The effects of interactions were not included in the results because earlier analyses including all the interactions showed that they were not important. Level and period of feed restriction during the starter stage had an effect (P<0.05) on live weight of the chickens at 21 days of age. Chickens on 75% ad libitum feeding attained complete live weight compensation with those on Ad-libitum feeding at the age of 42 days. However, chickens on 50% ad libitum feeding did not ‘catch-up’ with those on ad libitum feeding. Differences due to the period of feed restriction during the starter stage were maintained up to the age of 42 days. Male chickens had higher (P<0.05) live weights at 42 days of age. Abdominal fat pad was not affected (P>0.05) by level and period of feed restriction and sex of chickens at 42 days of age.
  C.A. Mbajiorgu , J.W. Ng`ambi and D. Norris
  An experiment was conducted to evaluate the effect of time of initiation of feeding after hatching and influence of dietary ascorbic supplementation during realimentation on productivity, carcass characteristics and mortality of Ross 308 broiler chickens. The study was a factorial arrangement in a complete randomized design. Six hundred and seventy five unsexed Ross 308 broiler chickens with an initial weight of 32±2 g per bird were assigned to 15 treatments in a 3 (times of initiation of feeding) x 5 (ascorbic acid supplemental levels) factorial arrangement with three replications, each having 15 birds each. The experimental diets were isocaloric and isonitrogenous but with different ascorbic acid supplementation levels. Ascorbic acid supplementation started three days after hatching. More than 50% of the birds died between one and three days of age when initiation of feeding after hatching was above 36 hours. Time of initiation of feeding above 36 hours of hatching resulted in lower (p<0.05) live weight between one and three days of old. However, the birds ‘caught-up' within ten days of realimentation. This compensatory growth could be explained in terms of increased efficiency of growth. Thereafter, ascorbic acid supplementation during realimentation lowered (p<0.05) mortality rate and improved (p<0.05) growth rates and live weight irrespective of time of initiation of feeding after hatching. Growth rate and live weight increased incrementally with increasing levels of ascorbic acid supplementation within each time of initiation of feeding after hatching in comparison with those without ascorbic acid supplementation at 21 day of age and continued until 42 days of age. Similarly, increasing ascorbic acid supplementation within each time of initiation of feeding after hatching increased dressing percentage and breast meat yield at 42 days old. However, ascorbic acid supplementation had no effect (p>0.05) on feed intake of the bird's irrespective of time of initiation of feeding after hatching. It is concluded that time of initiation of feeding above 36 hours after hatching is not desirable, mainly because of its effect on mortality. However, the beneficial effect of ascorbic acid supplementation could be exploited in reducing mortality rate and improving growth rates in broiler chickens subjected to delayed initiation of feeding after hatching.
  D.J. Novel , J.W. Ng`ambi , D. Norris and C.A. Mbajiorgu
  An experiment was conducted to determine the effect of different feed restriction regimes during the starter stage (14-21 days) on productivity and carcass characteristics of male and female Ross 308 chickens. A 3 (feeding levels: ad-libitum intake, 50% ad-libitum intake and 75% ad-libitum intake) x 2 (male and female chickens) factorial arrangement in a complete randomized design was used. Feed restriction affected (p<0.05) live weight of chickens at the age of 21 days and male chickens were heavier (p<0.05) than females at the same age. Chickens on 75% ad libitum feeding attained complete compensation in live weight at 42 days of age while those on 50% ad libitum feeding did not. However, male chickens attained higher (p<0.05) live weights than female chickens at 42 days of age. It is suggested that 75% ad libitum restriction feeding during the starter stage from 14 up to 21 days of age may offer some economic advantage over ad-libitum feeding regimen, mainly by enhancing feed utilization. It may, therefore, be a useful nutritional strategy to reduce the cost of commercial starter grain based-diets.
  J.W. Ng`ambi , P.M. Nakalebe , D. Norris , M.S. Malatje and C.A. Mbajiorgu
  The study was conducted to determine the effect of dietary energy level and tanniniferous Acacia karroo leaf meal level of supplementation at finisher stage on performance and carcass characteristics of male and female Ross 308 broiler chickens. Three hundred and sixty, 21 days old male and female broiler chickens were assigned to twelve treatments with three replications of ten birds in a 2 (sex) x 3 (dietary energy level) x 3 (tanniniferous Acacia karroo leaf meal level) factorial, complete randomized design. Supplementation with Acacia karroo leaf meal had no effect on diet intake, digestibility and live weight of broiler chickens. However, supplementation with 9 and 12 g of Acacia karroo leaf meal per kg DM feed reduced fat pad weights in male broiler chickens by 26 and 29% points, respectively. Similarly, supplementation with 9 and 12 g of Acacia karroo leaf meal per kg DM feed reduced fat pad weights in female chickens by 26% points. These reductions were achieved without any significant reduction in feed intake and digestibility. However, the physiological explanation for this effect is not clear and it, thus, merits further investigation.
  J.W. Ng`ambi , D. Norris and C.A. Mbajiorgu
  This study was conducted to determine trends in annual rainfall oscillations and mohair production in Lesotho between 1935 and 1996. An exponential regression equation of the form LnY = LnA + bx was used to estimate trends. Between 1935 and 1965 Angora goat numbers, mohair production and mohair yield per goat increased (p<0.01) at annual rates of 1.1, 1.9 and 1.1%, respectively. During years of independence (1966-1996) annual goat numbers remained, largely, stagnant (p>0.05) at around one million animals. Mohair yield per goat declined (p<0.01) at an annual rate of 1.2% to around 0.85 kg in 1996. Similarly, mohair production declined (p<0.01) at an annual rate of 1.2% to 970,000 kg in 1996. A long-term (1935-1996) annual rainfall mean of 700 mm was calculated. There were recurrent wet (rainfall above long-term mean) and dry (rainfall below long-term mean) years. However, no clear alternate rainfall oscillations of wet and dry years were observed. It was, thus, difficult to predict years of drought (rainfall below long-term mean) from alternate annual rainfall oscillations. A positive but non-significant (p>0.05) relationship between annual mohair yield per goat (kg) and rainfall (mm) was observed. Policy implications of the results on drought preparedness are discussed.
 
 
 
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