No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Thesis (M.Sc. (Animal Production)) -- University of Limpopo, 2018 / The study was conducted to determine the macroscopic and microscopic raw semen characteristics of Bapedi rams, to evaluate the effect of different egg yolk (EY) concentrations in Tris-based extenders on cryopreservation of Bapedi ram semen and to determine the effect of supplementing different phosphatidylcholine (PC) concentrations in Tris-based extenders with or without egg yolk on cryopreservation of Bapedi ram semen. Semen ejaculates were collected from four matured Bapedi rams aged 2-4 years using artificial vagina (AV) and pooled to eliminate individual differences. The first experiment was performed to characterise Bapedi ram semen parameters immediately after semen collection. The macroscopic semen parameters such as volume, pH and concentration and microscopic semen parameters such as motility, viability and morphology, membrane integrity and acrosome integrity were evaluated. The experiment was replicated 8 times and the data was subjected to descriptive statistics. The second experiment evaluated the effect of Tris-based extenders with five different EY concentrations (0, 5, 10, 15 and 20 %) on the microscopic quality of cryopreserved Bapedi ram semen. The treatments were subjected to a Completely Randomized Design (CRD) and replicated 4 times. The third experiment evaluated the effects of different PC concentrations supplemented to Tris-based extenders with or without 10% EY and the PC was added as liposomes. The experiment was a 2 x 4 factorial design in a CRD with two concentrations of EY: 0 and 10 %, and four concentrations of PC: 0, 0.25, 0.50, 0.75 mg/ml in Tris-based extenders. Pooled semen samples were divided into 5 and 8 aliquots to comply with objective 2 and objective 3, respectively. The semen aliquots were diluted with Tris-based extenders and equilibrated in a refrigerator at 5°C for another 4 hours. The semen was frozen using a programmable freezer and plunged into liquid nitrogen tank (-196°C).The volume, sperm concentration and pH of Bapedi ram semen ranged between 0.4-1.5 ml, 0.52-8.84 × 109 sperm/ml, and 5-7, respectively. The average total motility (TM), progressive motility (PM) and rapid motility (RM) characteristics were 85.95±2.58 %, 29.33±2.11 % and 39.47±4.99 %, respectively. The results for the mean percentage live spermatozoa, abnormalities, intact membrane and intact acrosome were 70.19±2.29 %, 2.50±1.34 %, 72.39±1.71 % and 75.37±5.39 %, respectively. There was a general decrease trends in frozen-thawed motility characteristics such as TM, PM and RM as compared to raw semen (p<0.05). The frozen-thawed semen in Tris-based extenders with 10, 15 and 20% EY concentrations resulted in significantly (p<0.05) higher TM, PM and RM motility characteristics compared to 0 and 5%. The percentage of live spermatozoa, membrane and acrosome integrities were found higher in raw semen than in frozen–thawed semen of respective extenders (p<0.05). The supplementation of PC in extenders either with or without EY did not improve the TM, PM and RM parameters (p>0.05). The membrane integrity in extenders either with or without EY were not influenced by the supplementation PC after freezing and thawing (p>0.05). The supplementation of PC in treatments with EY did not improve the acrosome integrity (p>0.05). Interestingly, the supplementation 0.75 mg/ml PC resulted in acrosome integrity that was not significantly different (P>0.05) to treatments with EY. In conclusion, the macroscopic and microscopic semen parameters of raw Bapedi ram semen were characterized. The use of 10% EY concentration resulted in higher motility parameters and membrane integrity of frozen-thawed Bapedi ram semen. However, 20% EY resulted in higher acrosome integrity of frozen-thawed Bapedi ram semen. The supplementation of PC in extenders in extenders with or without EY did not improve the motility parameters, percentage live spermatozoa and membrane integrity. However, the acrosome integrity was improved in extenders without EY supplemented with 0.75 mg/ml PC / Agricultural research council professional development programme (ARC-PDP)

The impacts of supplemental L-threonine in laying hen diets were evaluated. Over three experiments, control hens were fed a corn-soybean commercial layer diet containing 0.56% threonine (Thr). Experimental diets containing 0.66, 0.76, 0.86, and 0.96% Thr were fed for experiment 1. Experimental diets containing 0.76, 0.96 and 1.16% Thr were fed for experiment 2. Experiment 1 and 2 hens were 42 weeks of age. In experiment 3, experimental diets containing 0.76 and 0.96% Thr were fed to aged hens (61 weeks at beginning of experiment). Data collection methods were the same for all three experiments. Beginning and ending hen weight, egg production, and feed consumption data were collected. Egg samples were analyzed for egg weight, yolk and albumen yield, protein, and functionality. In experiments 1 and 2, egg production increased with increasing dietary threonine levels up to 0.76% Thr in the diet and subsequently decreased suggesting a production threshold for the amino acid. Shell cracking strength increased with increasing threonine levels in all three experiments. In experiment 3, shell thickness increased with increasing threonine levels. Albumen protein was significantly increased when hens were fed increased levels of dietary threonine. Angel food cake volume was significantly increased in experiments 1 and 3 with increasing dietary threonine, as were other texture profile parameters. Sponge cake volume was significantly increased in experiments 2 and 3 as a result of increased threonine levels. In experiment 3, yolk gel hardness was significantly increased by increasing the level of dietary threonine. These data clearly indicate a potential important impact on egg composition and functionality by increasing dietary threonine nutrition of a laying hen.

Summary The aim of this study was to determine the egg production potentials of four different indigenous chicken breeds in South Africa: Potchefstroom Koekoek, Venda, Ovambo and Naked Neck. The White Leghorn breed was used as the control. The egg production potentials were evaluated over two consecutive production cycles of 52 weeks (used as replicates). Data were collected at the experimental farm of the Agriculture Research Council at Irene. Treatment means were separated using Fisher’s protected t-test least significant difference at the 5 percent level of significance and the percentage mortality rate by means of a row by column chi-square test. No significant differences were observed between breeds on the mean age to the production of the first egg. The White Leghorn was superior ( p ≤ 0.05) to all four of the indigenous breeds for the mean number of eggs and percentage hen-housed egg production produced per production cycle. The Potchefstroom Koekoek was also superior ( p ≤ 0.05) to the other three indigenous breeds for these parameters. There was no difference between the Ovambo and Naked Neck breeds. The percentage mortality rate for the White Leghorn (39.5 percent) was significantly ( p ≤ 0.05) different from that of the Venda, Ovambo and Potchefstroom Koekoek (22.2 percent). No differences were observed among the Potchefstroom Koekoek, Venda, Ovambo and Naked Neck (32.3 percent) or between the White Leghorn and Naked Neck with regard to the mean percentage mortality.