Antibiotics are routinely used in modern livestock production systems to treat and prevent disease as well as to enhance livestock production and/or outputs. This widespread use of antibiotics has led to a growing worldwide interest in antibioticfree animal production. The addition of feed supplements such as nucleotides to improve intestinal health as well as the early development of the immune system needs to be investigated as an environmentally-friendly nutritional management activity. In this study four (4) groups of newborn Holstein calves (n=24) were evaluated after being treated as follows: Group 1 (Negative control), Group 2 (Investigational Veterinary Product (IVP) 1 – Oral supplement containing nucleotides, vitamins, essential fatty acids, essential amino acids, pre-biotics and trace-minerals), Group 3 (IVP 2 – Oral supplement containing nucleotides only at concentration and dosage equal to IVP1) and Group 4 (IVP 3 - Parenteral glucocorticoids). Results of the study indicated that: Pre-colostral Serum IgG titres – After titration of the serum the anti-BVDV results showed no difference between the study groups. All calves recorded a SP ratio of zero value (0.00 ± 0.2) indicating that they had not been nursed by their mothers prior to the start of the study. This was an entrance requirement for the calves to be enrolled into the study. Apparent Efficiency of Absorption % (AEA%) – Literature shows that an AEA% result of between 20%-30% is good and 35% is excellent. The AEA% recorded for this study fell within this range although there was no statistically significant difference shown between the groups. In spite of a strictly controlled study protocol, 7 of the 24 calves (29%) still suffered from FPT in this study. The result falls within the range of 19% - 37% reported on United States of America (USA) farms by Doepel and Bartier in 2014. Serum cortisol - When compared to the control group, there were no statistical significant difference evident for group 2 and group 3. However, the difference between the Glucocorticoid – Group 4 and the control and other groups was statistically significant (P = 0.0001; table 12) at the various time intervals. It was also evident that the inclusion of parenteral glucocorticoids (group 4) may have assisted in prolonging the natural “gut closure”. Gut closure – a positive 2 point linear regression forecast line indicated an increasing trend in IgG absorption post-24 hours for group number 4 whilst groups 1, 2 and 3 each had a negative 2 point linear regression forecast line (figure 23). Weight / ADG (D42) - Group 2 showed a statistically significant increase in mean D42 weight (P = 0.0042) of 59.167 kg ± 3.545 kg when compared to the other study groups and compared to the control group (P = 0.0227). A comparison of the relative increase in mass of groups indicated that Group 2 efficiently achieved this result with a statistically significant ADG of 0.536 kg (P = 0.014) compared to the other study groups and compared to the control group (P = 0.022). In addition, weight / FCR – FCR was calculated for all groups as follows: G1 – 4.000 kg, G2 - 2.593 kg, G3 – 2.703 kg and G4 - 3.012 kg feed required for the production of 1 kg meat. The results indicated that the group 2 feed input was the most economical followed by groups 3, 4 and control respectively. In conclusion, it is evident that a nutritional supplement containing nucleotides, vitamins, trace- minerals, essential fatty acids, essential amino acids and pre-biotics may contribute significantly to important economic indicators such as weight gain, ADG and FCR on a commercial dairy farm. / Environmental Sciences / Ph. D. (Environmental Science)

Antibiotics are routinely used in modern livestock production systems to treat and prevent disease as well as to enhance livestock production and/or outputs. This widespread use of antibiotics has led to a growing worldwide interest in antibioticfree animal production. The addition of feed supplements such as nucleotides to improve intestinal health as well as the early development of the immune system needs to be investigated as an environmentally-friendly nutritional management activity. In this study four (4) groups of newborn Holstein calves (n=24) were evaluated after being treated as follows: Group 1 (Negative control), Group 2 (Investigational Veterinary Product (IVP) 1 – Oral supplement containing nucleotides, vitamins, essential fatty acids, essential amino acids, pre-biotics and trace-minerals), Group 3 (IVP 2 – Oral supplement containing nucleotides only at concentration and dosage equal to IVP1) and Group 4 (IVP 3 - Parenteral glucocorticoids). Results of the study indicated that: Pre-colostral Serum IgG titres – After titration of the serum the anti-BVDV results showed no difference between the study groups. All calves recorded a SP ratio of zero value (0.00 ± 0.2) indicating that they had not been nursed by their mothers prior to the start of the study. This was an entrance requirement for the calves to be enrolled into the study. Apparent Efficiency of Absorption % (AEA%) – Literature shows that an AEA% result of between 20%-30% is good and 35% is excellent. The AEA% recorded for this study fell within this range although there was no statistically significant difference shown between the groups. In spite of a strictly controlled study protocol, 7 of the 24 calves (29%) still suffered from FPT in this study. The result falls within the range of 19% - 37% reported on United States of America (USA) farms by Doepel and Bartier in 2014. Serum cortisol - When compared to the control group, there were no statistical significant difference evident for group 2 and group 3. However, the difference between the Glucocorticoid – Group 4 and the control and other groups was statistically significant (P = 0.0001; table 12) at the various time intervals. It was also evident that the inclusion of parenteral glucocorticoids (group 4) may have assisted in prolonging the natural “gut closure”. Gut closure – a positive 2 point linear regression forecast line indicated an increasing trend in IgG absorption post-24 hours for group number 4 whilst groups 1, 2 and 3 each had a negative 2 point linear regression forecast line (figure 23). Weight / ADG (D42) - Group 2 showed a statistically significant increase in mean D42 weight (P = 0.0042) of 59.167 kg ± 3.545 kg when compared to the other study groups and compared to the control group (P = 0.0227). A comparison of the relative increase in mass of groups indicated that Group 2 efficiently achieved this result with a statistically significant ADG of 0.536 kg (P = 0.014) compared to the other study groups and compared to the control group (P = 0.022). In addition, weight / FCR – FCR was calculated for all groups as follows: G1 – 4.000 kg, G2 - 2.593 kg, G3 – 2.703 kg and G4 - 3.012 kg feed required for the production of 1 kg meat. The results indicated that the group 2 feed input was the most economical followed by groups 3, 4 and control respectively. In conclusion, it is evident that a nutritional supplement containing nucleotides, vitamins, trace- minerals, essential fatty acids, essential amino acids and pre-biotics may contribute significantly to important economic indicators such as weight gain, ADG and FCR on a commercial dairy farm. / Environmental Sciences / Ph. D. (Environmental Science)

Twenty four Jersey calves were randomly blocked according to sex and birth date, to determine the effects of supplementing Carica papaya seed (Linn) meal (CPSM) on health and growth performance of calves. In the first study, calves were fed CPSM for only 2 days to determine faecal pathogen population. In the second study; calves were randomly assigned at birth to three treatments and fed until weaning at 42 days. Each treatment had six calves. Treatments were; 1) a control group, which did not receive additive; 2) a group that was supplemented 5 g/d of Carica papaya seed meal (CPSM) and 3) the last group that was supplemented 5 g/d of a commercial product containing Lactobacillus acidophilus (Lact). After receiving milk with colostrum from their dams for 3 consecutive days after birth, calves had commercial starter pellet and fresh water ad lib. Treatments were added to whole milk from day 4 and fed to calves before being allowed to suckle from the dams for 30 min three times a day (08:00; 12:00 and 17:00). Calf starter dry matter intake (DMI) was evaluated daily while body weight (BW) and body structural growth were measured weekly. Faecal samples were collected directly from the rectum on day 7 and 10, before and after receiving CPSM respectively. The DMI; DMI/BW; BW and BWG of calves did not differ among treatments, and averaged 305.4 g/d; 7.7 g/d per BW; 39.4 kg and 32.1 kg, respectively. The initial BW, 22.2 ± 1.49 kg did not differ among groups, but the weaning BW was higher (p<0.05) for CPSM fed calves compared to control diet fed calves. It did not differ between control and Lact calves. Calves in Lact and CPSM treatments had similar average daily gain (ADG) and heart girth (HG), which were higher (p<0.05) than calves fed the control treatment. Calves fed CPSM had higher (p<0.05) hip width (HW) and shoulder height (SH) than control calves. There were effects of time (p<0.001) for starter DMI/BW, ADG and all structural body parameters, and effects (p<0.05) of interaction between time and treatments for only starter DMI/BW, ADG and HG. The CPSM treatment reduced faecal coliforms and E. coli (p<0.05) by 93.6% and 96.1%, respectively; and tended to reduce Enterobacteriaceae (p=0.056) by 96.4%. The present study revealed that feeding CPSM to calves during the pre-weaning period increased growth performance by improving average daily gain, feed efficiency and enhancing health status due to low faecal pathogen count / Agriculture, Animal Health and Human Ecology / M. Sc. (Agriculture)