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The overall objective of this research was to define the cellular basis underlying heritable subfertility in roosters homozygous for the rose comb allele (R/R). Fertilization in the hen is preceded by the ascension of motile sperm through the vagina and sperm sequestration within sperm storage tubules (SST). The objective of the first set of experiments was to determine if reduced sperm sequestration could account for subfertility. Sperm sequestration differed between genotypes following intravaginal insemination (p<0.0001). However, sperm sequestration did not differ between genotypes when sperm were incubated with SST in vitro (p>0.05). Therefore, subfertility was attributed to reduced sperm transport within the vagina. To test this hypothesis, an assay was developed to evaluate fowl sperm motility in vitro. Based upon this assay, ejaculates from subfertile males contained smaller subpopulations of highly motile sperm than the ejaculates from controls (p<0.001). The objective of the next set of experiments was to characterize the motility of individual sperm and to identify a mechanism that could account for the genotypic difference in sperm cell motility. Computer-assisted sperm motion analysis evaluation revealed that ejaculates from controls contained 91% motile sperm whereas ejaculates from subfertile males contained 62% motile sperm (p<0.001). The ATP concentration in sperm from subfertile males was 63% less than that of sperm from controls (p<0.001). A link between sperm ATP concentration and immotility was investigated. First, sperm metabolism was evaluated using motility as an endpoint. The genotypic difference in sperm motility persisted when ATP synthesis was limited to glycolysis (p<0.001). Consequently, mitochondrial respiration could not account for the genotypic difference in sperm motility. In contrast, sperm uptake of [1,2-��H] 2-deoxy-D-glucose did differ between genotypes (p<0.001). The activity of key glycolytic enzymes, creatine kinase, and dynein ATPase did not differ between genotypes (p>0.05). Therefore reduced sperm motility did not appear to be due to ATP synthesis, allocation of high energy phosphate bonds along the axoneme, or ATP consumption (p>0.05). In conclusion, subfertility of roosters homozygous for the rose comb allele was attributed to decreased spermatozoal glucose transport. / Graduation date: 1997

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In 1957, strains 3 and 4, two highly selected but unrelated strains of Single Comb White Leghorn chickens from Agriculture Canada's Animal Research Station at Ottawa were crossed to establish the Agassiz strain (strain 6). Further selection was imposed on strain 6 for improvements in hen-housed egg production (HHEP) based on part-records to 273 days and maintenance of egg weight, fertility, hatchability and viability. Data from 1957 to 1963 were analysed utilizing the SAS programs. There were no significant improvements in performance for HHEP, but egg weight, fertility, hatchability and viability were maintained. The lack of response to selection for HHEP was probably due to the following reasons: 1) too many traits were considered in the selection program at the same time, 2) negative genetic correlations existed among the selected traits, 3) strict adherence to a selection scheme was not practiced, 4) most of the traits under selection had low heritabilities, 5) the duration of the study was not long enough, and 6) the population size of strain 6 may not have been large enough. There was a significant decrease in body weight at 365 days (-4.33 ± 0.48, p < 0.0009). This decrease may be because of selection within full-sibs for more refined birds with better conformation as parents of the next generation. There were significant decreases in egg specific gravity at 225 and 450 days, and in Haugh units at 225 days, although Haugh units were increasing when measured at 450 days. The mean h²s for HHEP was 0.45, and the mean h²s for egg production to 273 days was 0.20 and the mean h²d for the same trait was 0.33. The mean h²s and h²d estimates for egg weight at 225 days were 0.60 and 0.50, respectively. The mean h²s and h²d for age at sexual maturity were 0.22 and 0.33, respectively, and those for body weight at 365 days were 0.53 and 0.62, respectively. The mean h²s and h²d for egg specific gravity at 225 were 0.64 and 0.33, respectively while those for Haugh units at 225 days were 0.57 and 0.68, respectively. These estimates were consistent with those found in the literature. The sctual selection differentials showed that selection was positive for egg production, while those for egg weight at 225 days were zero, and those for body weight at 365 days showed that selection was in the downward direction on the sires. / Land and Food Systems, Faculty of / Graduate

Thesis (MA. Agric. (Animal Production)) -- University of Limpopo, 2014 / This study determined the effect of carrot meal supplementation on productivity and carcass characteristics of Arbor acres broiler chickens aged one to six weeks. Experiment I determined the effect of carrot meal supplementation on productivity of Arbor acre broiler chicks aged one to 21 days. Two hundred unsexed Arbor acre broiler chickens were randomly assigned to five treatments with five replicates, each replicate having ten birds. A completely randomized design was used in the first experiment. The treatments were 0 (UA0), 20 (AU20), 50 (AU50), 75 (AU75) or 100 (AU100) g of carrot meal supplementation per kg DM feed. Quadratic equations were used to determine levels of carrot meal supplementation for optimal feed intake, metabolisable energy intake and nitrogen retention of Arbor acre broiler chickens aged one to 21 days. Linear equations were used to determine relationships between carrot meal supplementation and productivity variables. Dietary carrot meal supplementation had no (P>0.05) effect on growth rate, live weight and feed conversion ratio of unsexed Arbor acre broiler chickens aged one to 21 days. Carrot meal supplementation, however, improved (P<0.05) metabolisable energy intake and nitrogen retention of the chickens. Dietary metabolisable energy intake and nitrogen retention of the chickens were optimized at different carrot meal supplementation levels of 40.5 and 53.57 g/kg DM feed, respectively. No chicken deaths were recorded. Experiment II determined the effect of carrot meal supplementation on productivity and carcass characteristics of female Arbor acre broiler chickens aged 22 to 42 days. The chickens were randomly allocated to five treatments with five replicates, each having 10 birds, in a completely randomized design. The supplementation levels were 0 (FA0), 20 (FA20), 50 (FA50), 75 (FA75), or 100 (FA100) g of carrot meal per kg DM feed. Quadratic equations were used to determine levels of carrot meal supplementation for optimal feed intake, feed conversion ratio, live weight, metabolisable energy intake and nitrogen retention of broiler chickens aged 22 to 42 days. Linear equations were used to determine relationships between carrot meal supplementation and production variables. Dietary carrot meal supplementation had no (P>0.05) effect on growth rate, live weight and carcass parts of female Arbor acre broiler chickens aged 22 to 42 days. Carrot meal supplementation improved (P<0.05) feed intake, feed conversion ratio, metabolisable energy intake and nitrogen retention of Arbor acre broiler chickens aged vi 22 to 42 days. Dietary feed intake, feed conversion ratio, live weight, metabolisable energy intake and nitrogen retention were optimized at different dietary carrot meal supplementation levels of 52.8, 63.8, 38.0, 42.0 and 44.3 g/kg DM feed, respectively. Dietary carrot meal supplementation had no effect (P>0.05) on tenderness and flavour of female Arbor acre broiler meat. Broiler chickens on diets supplemented with 20, 50 or 100 g of carrot meal per kg DM feed produced meat with better (P<0.05) juiciness values than those of meat from chickens not supplemented with dietary carrot meal and those supplemented with 75 g/kg DM feed. There was a positive relationship between carrot meal supplementation and chicken meat juiciness. It is concluded that carrot meal supplementation improved (P<0.05) metabolisable energy intake and nitrogen retention of unsexed Arbor acre broiler chickens aged one to 21 days. However, carrot meal supplementation had no effect (P>0.05) on growth rate, live weight and feed conversion ratio of unsexed Arbor acre broiler chickens aged one to 21 days. Carrot meal supplementation improved (P<0.05) intake, feed conversion ratio, metabolisable energy and nitrogen retention of female Arbor acre broiler chickens aged 22 to 42 days. However, carrot meal supplementation did not (P>0.05) improve growth rate and live weights of the chickens.

Thesis (MA. Agricultural Management (Animal Production)) -- University of Limpopo, 2014 / This study determined the effect of carrot meal supplementation on productivity and carcass characteristics of Arbor acres broiler chickens aged one to six weeks. Experiment I determined the effect of carrot meal supplementation on productivity of Arbor acre broiler chicks aged one to 21 days. Two hundred unsexed Arbor acre broiler chickens were randomly assigned to five treatments with five replicates, each replicate having ten birds. A completely randomized design was used in the first experiment. The treatments were 0 (UA0), 20 (AU20), 50 (AU50), 75 (AU75) or 100 (AU100) g of carrot meal supplementation per kg DM feed. Quadratic equations were used to determine levels of carrot meal supplementation for optimal feed intake, metabolisable energy intake and nitrogen retention of Arbor acre broiler chickens aged one to 21 days. Linear equations were used to determine relationships between carrot meal supplementation and productivity variables. Dietary carrot meal supplementation had no (P>0.05) effect on growth rate, live weight and feed conversion ratio of unsexed Arbor acre broiler chickens aged one to 21 days. Carrot meal supplementation, however, improved (P<0.05) metabolisable energy intake and nitrogen retention of the chickens. Dietary metabolisable energy intake and nitrogen retention of the chickens were optimized at different carrot meal supplementation levels of 40.5 and 53.57 g/kg DM feed, respectively. No chicken deaths were recorded. Experiment II determined the effect of carrot meal supplementation on productivity and carcass characteristics of female Arbor acre broiler chickens aged 22 to 42 days. The chickens were randomly allocated to five treatments with five replicates, each having 10 birds, in a completely randomized design. The supplementation levels were 0 (FA0), 20 (FA20), 50 (FA50), 75 (FA75), or 100 (FA100) g of carrot meal per kg DM feed. Quadratic equations were used to determine levels of carrot meal supplementation for optimal feed intake, feed conversion ratio, live weight, metabolisable energy intake and nitrogen retention of broiler chickens aged 22 to 42 days. Linear equations were used to determine relationships between carrot meal supplementation and production variables. Dietary carrot meal supplementation had no (P>0.05) effect on growth rate, live weight and carcass parts of female Arbor acre broiler chickens aged 22 to 42 days. Carrot meal supplementation improved (P<0.05) feed intake, feed conversion ratio, metabolisable energy intake and nitrogen retention of Arbor acre broiler chickens aged vi 22 to 42 days. Dietary feed intake, feed conversion ratio, live weight, metabolisable energy intake and nitrogen retention were optimized at different dietary carrot meal supplementation levels of 52.8, 63.8, 38.0, 42.0 and 44.3 g/kg DM feed, respectively. Dietary carrot meal supplementation had no effect (P>0.05) on tenderness and flavour of female Arbor acre broiler meat. Broiler chickens on diets supplemented with 20, 50 or 100 g of carrot meal per kg DM feed produced meat with better (P<0.05) juiciness values than those of meat from chickens not supplemented with dietary carrot meal and those supplemented with 75 g/kg DM feed. There was a positive relationship between carrot meal supplementation and chicken meat juiciness. It is concluded that carrot meal supplementation improved (P<0.05) metabolisable energy intake and nitrogen retention of unsexed Arbor acre broiler chickens aged one to 21 days. However, carrot meal supplementation had no effect (P>0.05) on growth rate, live weight and feed conversion ratio of unsexed Arbor acre broiler chickens aged one to 21 days. Carrot meal supplementation improved (P<0.05) intake, feed conversion ratio, metabolisable energy and nitrogen retention of female Arbor acre broiler chickens aged 22 to 42 days. However, carrot meal supplementation did not (P>0.05) improve growth rate and live weights of the chickens.

Thesis (M.A. Agricultural Management (Animal Production)) -- University of Limpopo, 2013 / The objectives of the study were to evaluate the productivity of the Vhembe egg production project and determine the management and socio-economic factors affecting productivity. The data were collected from 2005 to 2007. Thirty-two farmers from four municipalities were randomly selected. Each household received a once-off unit consisting of a cage with eighteen point of lay chickens 4x50 bags of laying mesh, feeding and drinking troughs. Production records from sampled farmers were used in the analysis. Data included monthly egg production, eggs consumed, eggs sold, income from eggs, production costs, monthly feed utilization and mortality. Primary data on educational standards, socio-economic characteristics (age and gender of the household head, farming size, level of education and alternative income, were collected using a questionnaire. The study revealed that sex, age and educational level had impact on production as low production was associated with older farmers and low level of education. These factors should be considered when planning community projects. Chicken rearing and ownership is often shared among the family members, in this study, the management was predominantly by women (63%) and children (18%). This may be an indication that if assistance efforts are targeted towards women, village poverty could be significantly reduced. It is concluded that the low income accrued from the project explains the reason for high abandonment or neglect of the project. The income received from the project is smaller than the government grants and as such not attractive. It is not surprising that presently most farmers have abandoned the project. It is noted that if labour costs had been taken into consideration, the project would be running at a serious loss and the resultant output would discourage even the most enthusiastic farmers.

Thesis (Bsc. (Animal production)) --University of Limpopo, 2009. / Two experiments were conducted to evaluate the effect of Hoodia gordonii meal supplementation at finisher stage on productivity and carcass characteristics of Ross 308 broiler chickens. Experiment 1 examined the effect of levels of Hoodia gordonii meal supplementation of grower diet fed to Ross 308 broiler chickens at the finisher stage (30 – 42 days of age) on productivity and carcass characteristics in a 12 day experimental period. The experiment was a completely randomized design with a 2 (two sexes of chickens) x 6 (levels of Hoodia gordonii meal [0, 100, 200, 300, 400 or 500 mg]) factorial arrangement of treatments in which three hundred and sixty broiler chickens at finisher stage were randomly allocated to twelve treatments with three replicates of ten birds each. Level of Hoodia gordonii meal supplementation had no effect (P>0.05) on diet intake, intake as percentage of live weight, growth rate, feed conversion ratio, live weight at 42 days of age and mortality of broiler chickens at finisher stage. All carcass characteristics were not affected (P>0.05) by the treatments except fat pads. Chickens given a daily dose of 300 mg of Hoodia gordonii meal had lower (P<0.05) fat pad weights than unsupplemented ones. Male broiler chickens had higher (P<0.05) feed intake and heavier drum sticks than female broiler chickens. Experiment 2 examined the effect of Hoodia gordonii meal dose interval at finisher stage in a 2 (two sexes of chickens) x 3 (dosage intervals) factorial, complete randomized design that involved three hundred and sixty chickens that were randomly allocated to six treatments with six replicates of ten birds each. Broiler chickens were fed either a grower diet without Hoodia gordonii meal; grower diet with 300 mg of Hoodia gordonii meal/ bird supplemented everyday for 12 days; or grower diet with 300 mg of Hoodia gordonii meal/ bird supplemented twice, on 30th and 36th days of age. Hoodia gordonii meal dose interval had no effect (P>0.05) on dry matter feed intake, intake as percentage of live weight, growth rate, live weight at 42 days of age, feed conversion ratio, mortality and all carcass characteristics except fat pad of broiler chickens. Daily dosing with 300 mg of Hoodia gordonii meal/ bird reduced (P<0.05) fat pad weights of broiler chickens by 18 percentage points. Male broiler chickens had higher (P<0.05) feed intake, nitrogen digestibility, nitrogen retention and live weight than female broiler chickens. It is concluded that chickens given a daily supplement of 300 mg of Hoodia gordonii meal had lower fat pad weights than unsupplemented ones. This could not be explained in terms of differences in feed intake, digestibility, or growth rate.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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