Antimicrobial efficacy of recently approved lytic bacteriophage preparation Salmofresh™ against Salmonella was evaluated on chicken breast fillets as dip and surface application, which reduced Salmonella by 0.7-0.9 log CFU/g and 0.8-1 log CFU/g, respectively. Surface application of Salmofresh™ on Salmonella inoculated chicken breast followed by storage under modified atmosphere packaging (95% CO2/ 5% O2) reduced Salmonella by 1.2 log CFU/g. The combined application of Salmofresh™ with cetylpyridinium chloride (CPC) and lauric arginate (LAE) reduced Salmonella on chicken breast fillets by 1.2-1.4 log CFU/g and 0.9-1 log CFU/g, respectively. The sequential application of chemical antimicrobial (CPC, LAE, chlorine and peracetic acid) and Salmofresh™ in reducing Salmonella was tested in a chicken skin model. Dip treatment in peracetic acid (400ppm) followed by surface application of phage revealed the highest reduction of Salmonella up to 2.5 log CFU/cm2 on chicken skin.

Porcine Semimembranosus muscles were vacuum tumbled with phosphate, without phosphate, fiber dry vinegar, or whey protein concentrate (WPC). Consumers preferred (P<0.05) deli ham with phosphate, without phosphate and WPC over the oat fiber with vinegar treatment. In addition, the phosphate treatment had less cooking loss, (P<0.05) greater bind strength (P<0.05) and more intact slices (P<0.05) than other treatments. In addition, WPC produced ham with a higher (P<0.05) CIE l* and a lower (P<0.05) b* value than other treatments. Consumers preferred (P<0.05) chicken breasts marinated with phosphate with respect to flavor and aroma over the negative phosphate treatment and oat fiber treatments. Chicken breast with phosphate increased pH and had less cooking loss (P<0.05) as compared to chicken with WPC and without phosphate. Results indicated that oat fiber has potential as a phosphate replacer in marinated chicken, and WPC has potential as a phosphate replacer in deli ham.

Melanocortins play a key role in appetite regulation across species. One such melanocortin, beta-melanocyte stimulating hormone (beta-MSH) is receiving increasing attention for its anorexigenic effects. In chicks selected for low (LWS) and high (HWS) juvenile body weight, beta-MSH differentially decreased food intake and HWS chicks may be more sensitive to its effects. Both lines responded similarly to beta-MSH with decreased water intake. While whole blood glucose concentrations and ingestive and non-ingestive behaviors (sit, stand, preen, perch, deep rest, jumps, escape attempts, feed pecks, defecations, and total distance traveled) were not affected in either line, beta-MSH increased corticosterone in LWS chicks but not HWS chicks. However, despite the increase in corticosterone concentration in LWS, astressin, a corticotrophin releasing hormone (CRH) receptor antagonist, did not attenuate the effects of beta-MSH in either line suggesting that the altered stress response may not be acting via CRH receptors. When beta-MSH was co-administered with HS014, a highly selective antagonist for the melanocortin 4 receptor, only LWS responded with an attenuated response to beta-MSH suggesting that the differential response may in part be due to altered receptor affinity or binding resulting from the selection process. To investigate the roles of the hypothalamus and hindbrain in the differential food intake response, an experiment was designed where chicks were injected targeting either the lateral or 4th ventricle utilizing a novel freehand injection procedure. Chicks from both lines responded similarly to beta-MSH following both lateral and 4th ventricle injections. Together, these data suggest that alterations in the b-melanocortinergic appetite regulation system may be in part responsible for the differential body weights of the LWS and HWS lines. [Adaptations of chapters II, III, and IV have been published in Neuroscience Letters, Journal of Neuroendocrinology, and Behavioural Brain Research, respectively] / Ph. D.

This study examined the effectiveness of UV radiation in reducing numbers of naturally occurring aerobic psychotrophic bacteria, lactic acid bacteria, Campylobacter and surface inoculated E. coli on split, boneless, skinless chicken breasts and the effects the UV treatments had on the taste of the chicken. The objective of the study was to determine the UV dosage that gave the largest amount of microbial kill without adversely affecting the taste of the chicken. Two groups of 12 breasts were individually vacuum packaged. One group was surface inoculated with 1ml of a 2.0 X 106 CFU/ml culture of generic E. coli. The other group received no inoculation. Two breasts from each group were treated with one of six different UV radiation doses, 0 mW s/cm2 (control-no exposure), 34mW s/cm2, 101mW s/cm2, 202mW s/cm2, 504mW s/cm2 and 1008mW s/cm2. Within 24 hr of the treatments and again after seven days, one breast from each group and each treatment was enumerated for bacterial load. The results showed that bacterial load on the inoculated UV treated breasts were significantly reduced (p <0.05) at every treatment level by an average of 1.5 logs compared to the inoculated controls. There were however, no significant differences (p >0.05) between the inoculated breasts at any of the five different UV treatment dosages. The non-inoculated breasts showed no significant differences in the numbers of bacteria on the controls, as compared to the breasts treated with any of the five UV doses (p >0.05). Another set of 50 breasts were individually vacuum packaged and divided into six groups. Five groups contained five breasts each. Each group was treated with UV doses of 202mW s/cm2, 504mW s/cm2, 1008mW s/cm2, 2016mW s/cm2 and 3024mW s/cm2 respectively. The control group (n=25) received no exposure. Within 48 hr, and again seven days after treatments, triangle tests for difference were conducted to see if the taste of the chicken had been affected by the treatments. A sensory panel detected a significant taste difference between the untreated chicken and chicken treated at 504mW s/cm2 (p <0.05) two days after treatment, and between the control and chicken treated at 2016mW s/cm2 seven days after treatment (p <0.05). / Master of Science

Campylobacter is considered to be the leading cause of acute bacterial gastroenteritis in humans in the United States with Campylobacter jejuni being responsible for 80-90% of those infections. Many cases of Campylobacter gastroenteritis have been linked to the consumption of raw or undercooked chicken. The population of bacteria on the breast skin has been reported to be greater than on other edible portions of the chicken carcass making this an important site to control the organism and to study bacterial attachment properties. This research examined the efficacy of trisodium phosphate (TSP)(10%), cetylpyridinium chloride (CPC)(0.1% & 0.5%), acidified sodium chlorite (ASC)(0.1%), Tween 80 (polysorbate 80) (1%) and water (50°C) for reducing the number of viable Campylobacter jejuni on inoculated chicken breast skin. All chemicals were evaluated using contact times of 30 sec., 3 min. or 10 min. Statistically significant (p £ 0.05) differences in the reduction of C. jejuni populations were observed across chemical treatments and contact time. When bacteria were applied before treatment, a reduction of >1.0 log10 CFU/skin was achieved with 0.5% CPC (2.89), 10% TSP (1.63), 0.1% ASC (1.52), and 0.1% CPC (1.42). When bacteria were applied after treatment, a reduction of >1.0 log10 CFU/skin was achieved with 0.5% CPC (4.67) and 10% TSP (1.28). The main effects of contact time were statistically significant (p=0.02) only when bacteria were applied after treatment. / Master of Science

Increasing feed efficiency and early body weight gain has always been a top priority in the poultry industry. This experiment was designed to study the effects of feed sources differing in energy and protein levels as well as yolk removal on behavior, feed efficiency, energy intake, body weight and GIT growth in newly hatched chicks. Chicks in Experiment 1, Trial 1, were White Plymouth Rock chicks from the 40th generation of a line selected for high body weight, fed either freeze dried unincubated yolk (Diet Y) or mash (Diet M-A) from day 0 to day 5, after which all chicks were fed Diet M-A. Chicks in Experiment 1, Trial 2 were males from a commercial layer stock fed either a choice of residual yolk (yolk harvested from newly hatched chicks) and unincubated yolk (Diet Y), or mash (Diet M-A) alone from day 0 to day 6, after which all chicks were fed Diet M-A. In these experiments where chicks were offered yolk as a feed source for a period of time, body weight gain was significantly reduced and mortality increased. There was evidence that Diet Y chicks, consuming a high-lipid feed, experienced decreased appetite. There were no differences in body weight between the two diet groups in Trial 1 or Trial 2 on day 0, but during the days in which yolk was fed, Diet M-A chicks maintained a weight advantage over Diet Y chicks. Chicks used in Experiment 2 were males from a commercial layer stock. Yolk sacs were surgically removed (Trt YR) from half of the chicks while the other half remained yolk-intact (Trt YI). From day 0 to day 6, all chicks were offered a choice of residual yolk (Diet Y) or mash (Diet M-A) and beginning on day 6, all chicks were fed Diet M-A. Throughout the experiment, the Trt YI chicks maintained their body weight advantage over the Trt YR chicks, but by day 13, the Trt YR chicks gained proportionately more body weight. Because of wastage, feed efficiency and energy intake values were not reported. The only difference in GIT data was the amount of chyme; its value was higher in the Trt YI chicks than in Trt YR chicks. Behavior results showed that Trt YI chicks stood more while Trt YR chicks rested more throughout the experiment. Chicks used in Experiment 3 were males from a commercial layer stock. This experiment consisted of 4 groups: Trt YI chicks fed Diet M-E (mash feed high in energy and protein), Trt YI chicks fed Diet M-A (mash feed lower in energy and protein), Trt YR chicks fed Diet M-E and Trt YR chicks fed Diet M-A. Serial dissections on days 6, 13 and 20 allowed for better understanding of effects of diet and/or treatment on the growth of selected parts of the GIT. On days 13 and 20, there were no differences due to diet or treatment for GIT data except for the consistent difference due to diet for relative weight of the gizzard, whose value was higher in the Diet M-A chicks. Similar to results from Experiment 2, on day 13, Trt YR chicks fed Diet M-A gained more body weight than the Trt YI chicks fed the same diet. Also consistent with Experiment 2, of chicks fed Diet M-A, the Trt YI chicks stood more than the Trt YR chicks. Due to unusually large feed consumption values, feed efficiency and energy intake data were not reported. / Master of Science

The uptake of amino acids is mediated by amino acid transporters and the peptide transporter, PepT1. The nuclear receptor PPARα may play a role in the activation of PepT1. The objectives of this study were to evaluate the effect of a fasting/refeeding regimen and gavaging a PPARα ligand on expression of chicken PepT1 and PPARα. During the fasting/refeeding trial, chicks were placed on a 24h fast and then divided into 3 groups (Continuously Fasted (CF), Refed/Food Withdrawn, and Refed Adlib) and sampled 1, 2, 3, 5 and 7h post-fast. Expression of PepT1 and PPARα increased almost 2-fold post-24h fast (P < 0.002). The CF group had highest expression for both genes (P < 0.0001) suggesting a coordinate change in PepT1 and PPARα expression during fasting, indicating a possible regulatory role for PPARα of PepT1. Oral gavage trials utilizing PPARα ligand WY- 14643 were conducted with layers and broilers. For the layer trial birds were gavaged daily for 3 d with 50 mg WY-14643/kg in carrier (Ligand) or with just carrier (No Ligand) and sampled on d4. For the broiler trial, birds were gavaged daily with 25 or 50 mg WY-14643/kg or just carrier and sampled on d2 or d3 post gavage. No difference in PepT1 was observed between the Ligand and No Ligand groups. In the layer trial, PPARα decreased 6-fold (P = 0.005) in the Ligand group. Broilers treated with WY-14643 showed no effect of ligand. These results indicate a difference between layers and broilers in response to WY-14643. / Master of Science

Thesis (M.Sc. (Animal Production)) --University of Limpopo, 2010 / A study was conducted to determine the effect of vitamin E supplementation to the diets of Venda hens on egg production, hatchability and chick productivity. The first part of the study determined the effect of vitamin E supplementation to the diets of Venda hens on feed intake, number of eggs, egg weight, egg content, egg hatchability and chick hatch-weight. Supplementation levels of 0, 200, 400, 800 and 1000 mg of vitamin E per kg DM feed were used in a completely randomized design having five replications with two birds per replicate. Vitamin E supplementation did not have any effect (P<0.05) on number of eggs and feed intake of Venda hens. However, egg weight, egg content, hatchability and chick hatch-weight of Venda chickens improved (P<0.05) with vitamin E supplementation. Dietary vitamin E supplementation values for optimal egg white weight, egg yolk nitrogen content, egg white nitrogen content, egg hatchability and number of eggs were 476 (r2 = 0.756), 750 (r2 = 0.170), 750 (r2 = 0.182), 445 (r2 = 0.670) and 113 (r2=0.966) mg of vitamin E per kg DM feed, respectively. The second part of the study determined the effect of vitamin E supplementation to the diets of Venda hens on performance of their progenies between one and seven weeks old. A completely randomized design was used. All the chickens were fed the same commercial grower diet. Dietary vitamin E supplementation to the diets of Venda hens had no effect (P<0.05) on growth rate and mortality of their progenies between one and seven weeks. Feed intake, feed conversion ratio and live weight of progenies improved (P<0.05) with supplementation of vitamin E to the diets of Venda hens. Dietary vitamin E supplementation to the diets of Venda hens did not have any effect (P<0.05) on dry matter intake, dry matter digestibility, nitrogen retention and metabolisable energy of their progenies at seven weeks old. vi The third part of the study determined the effect of vitamin E supplementation to the diets of Venda hens on performance of their male progenies aged between eight and 13 weeks. A completely randomized design was used. All the chickens were fed the same commercial grower diet. Vitamin E supplementation to the diets of Venda hens did not improve (P<0.05) feed intake, growth rate, feed conversion ratio, live weight and mortality of their male progenies between eight and 13 weeks old. However, Venda hens supplemented with vitamin E produced male progenies with improved (P<0.05) dry matter intake, digestibility, nitrogen retention metabolisable energy, breast meat nitrogen content, gizzard weight, liver weight and heart weight at 13 weeks old. Carcass weight, breast meat yield, drum stick, thigh and wing weight of chickens at 13 weeks old were not affected (P>0.05) by vitamin E supplementation to the diets of the hens It is concluded that supplementation of vitamin E to the diets of indigenous Venda hens improved (P<0.05) egg weight, egg content and chick hatch-weight during the laying period. Vitamin E supplementation to the diets of Venda hens improved (P<0.05) feed intake, live weight, feed conversion ratio, gizzard and liver weight of their progenies. Production variables were optimized at different levels of vitamin E supplementation. Thus, this study provided new information on the effect of vitamin E supplementation to the diets of indigenous Venda hens on chick productivity and carcass characteristics of their progenies.

Thesis (M.Sc. Agric.(Animal Science)) --University of Limpopo, 2011 / An experiment was conducted to determine the effect of egg weight on hatchability, hatch-weight and subsequent productivity of Venda chickens. A total of 360 Venda chicken eggs based on their weights were collected within one week and assigned to four treatments with five replicates of 18 eggs per replicate. A randomized design was used. The four treatment weights were below 49 g, between 50 and 59 g, between 60 and 69 g and above 70 g. the eggs were incubated for 21 days. The chicks were raised up to 13 weeks based on their treatments but fed a similar diet. Egg weight was positively and strongly correlated (r2 = 0.727) with hatchability. Similarly, egg weight was positively and strongly correlated (r2 = 0.0.953) with chick hatch-weight. Between one and seven weeks old, Venda chicks hatched from heavier eggs ate less (P< 0.05) than those hatched from lighter eggs. Heavier eggs hatched chicks with better (P< 0.05) feed conversion ratio. However, chicks hatched from heavier eggs tended to have higher (P< 0.05) live weight at seven weeks old than those hatched from lighter eggs. Heavier eggs tended to hatch chicks that had higher (P< 0.05) mortality rates. However, metabolisable energy and nitrogen retention of the chicks aged seven weeks was not (P> 0.05) affected by egg weight. Growth rate and live weight of the chicks aged between one and seven weeks were optimized at different Venda chicken egg weights of 56 (r2 = 0.514) and 60 (r2 = 0.870) g, respectively. Egg weight had no (P> 0.05) effect on metabolisable energy, feed conversion ratio, growth rate, live weight, carcass weight and carcass parts of Venda chickens aged between eight and 13 weeks except fat pad weight. Venda chickens hatched from lighter eggs had lower (P< 0.05) fat pad weights than those hatched from heavier eggs. Meat samples of chickens hatched from lighter eggs had higher (P< 0.05) nitrogen contents. It is concluded that Venda chicken egg weight affects (P< 0.05) egg hatchability, chick hatch-weight, growth rate, live weight and carcass characteristics of the chicken. However, these variables are optimized at different egg weights. This has implications on selecting eggs for incubation.

Thesis (M.Sc. (Animal Production)) --University of Limpopo, 2011 / Crossbreeding is one of the tools for exploiting genetic variation. The main purpose of crossing chickens is to produce superior crosses (i.e. make use of hybrid vigor), improve fitness and fertility traits.This study was carried out at the University of Limpopo Experimental Farm located in Limpopo, South Africa. The objective of the study was to evaluate the growth performance of differentpurebred and crossbred chicken genotypes. A 3 x 3 complete diallel mating system involving two indigenous breeds namely Venda (V) and Naked Neck (N) and one commercial broiler breed, Ross 308 (R), were used to produce three purebred (V x V, N x N, R x R), three crossbreds (R x V, R x N, V x N) and three reciprocals (V x R, N x R, N x V).The nine genetic groups were rearedfrom hatch to 13 weeks of age in a deep litter open house. Body weights of 180 chicks (20 chicks per genetic group), recorded at 0, 3, 5, 7, 9, 11, and 13 weeks of age, were used to estimate heterosis, general (GCA) and specific (SCA) combining abilities, maternal ability and reciprocal or sex-linked effects on body weights. Results showed that the Ross 308 had the heaviest body weight at all weeks of measurement except for hatch. With respect to crosses, the reciprocal V x R and the cross R x V had the heaviest body weights at 13 weeks (2448.40 and 2131.50 grams, respectively), although N x R had heavier body weight than R x V at all weeks of measurement except for hatch and 13th week. Results of heterosis estimates indicated that crossing between Venda male and Ross 308 female as well as between the Venda male and Naked Neck femalegave the highest heterotic effects for body weight(11.01% and 10.33%, respectively).General Combining Ability was significant (P≤0.01) for body weight from hatch to 13 weeks of age while SCA and Reciprocal effects (RE) were both significant (P≤0.05) for body weight at all ages of measurement except for hatch weight. The Ross 308 chicken gave the highest positive effect of GCA for body weight except for hatch weight. Venda sire crossed with Naked Neck dams gave the highest and positive effects of SCA for body weight. Naked Neck sire crossed with Venda dams had the highest positive estimate of RE for body weight except for the 13th week. Results show that using Venda chickens as a paternal breed in crossing with Naked Neck and Ross 308 females may improve growth performance of indigenous chickens.