Call number: LD2668 .T4 1951 C53 / Master of Science

Call number: LD2668 .T4 1955 K56 / Master of Science

Call number: LD2668 .T4 1966 R313 / Master of Science

Published Article / Direct feeding damage to head lettuce (Lactuca sativa L.) by varying aphid populations in two differently constructed shadehouse structures (fully- and partially covered) was examined. Fresh lettuce head weight, the number of lettuce leaves formed, and the number of lettuce leaves infested with aphids were compared between the two structures. Warmer months showed a significant lower fresh lettuce head weight in the fully covered structure with more aphid-infested leaves. During June/September, the mean number of aphid-infested leaves and aphid infestation levels were significantly higher in the partially covered structure. Visible feeding damage to the lettuce crop was restricted, but asymptomatic damage in terms of a decrease in head weight did occur under severe infestation levels.

Attention deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder diagnosed in childhood. It is largely accepted that ADHD is a product of gene-environment interactions and method of infant feeding has been proposed as a factor influencing the expression and/or severity of ADHD. The objectives of this study were to determine the relationship between infant feeding (i.e. formula feeding or breast feeding) and subsequent hyperactive/inattentive (H/I) behaviours and ADHD diagnosis and if the relationship between infant feeding and academic performance is moderated by H/I scale score. This study used data from the 2000/1, 2002/3, 2006/7 and 2008/9 cycles of the National Longitudinal Survey of Children and Youth (NLSCY) (n= 3,895) to follow children longitudinally from the age of 0 to 1 years old to 6 to 7 years old. Infant feeding at 0 to 1 years old, and child H/I score, ADHD diagnosis and academic performance scores at 6 to 7 years old were reported by the biological mother. Multivariable logistic and linear regression were used to determine the relationship between infant feeding and H/I score, ADHD and academic performance adjusting for a range of sociodemographic, birth and home environment factors. Breastfeeding for more than 12 months was found to be significantly associated with decreased H/I scale scores in the most adjusted model (OR=0.3; 95% CI 0.2-0.8, p<0.01). Infant feeding was not associated with ADHD diagnosis and there was no moderating effect of the H/I score on the relationship between breastfeeding and academic performance. A small proportion of mothers breastfeed beyond one year in Canada and this study shows that there might be important child benefits incurred by breastfeeding for longer than 12 months. / May 2016

To determine the relationship between infant-feeding practices and diarrhoeal infections, a descriptive survey was conducted to infants between six to 12 months of age. A guided interview was conducted to 105 mothers of infants who attended the health facilities of Mbabane, Swaziland. The results show that breast-feeding is routinely practiced by the majority of mothers and exclusive breast-feeding is very low, but supplementary feed in the form of formula or solids are introduced by the majority of respondents within the first three months of life. Infants who were given colostrum and breast milk had fewer diarrhoeal attacks. Other factors, for example education and cultural factors influenced the feeding practices and number of diarrhoeal attacks. It is recommended that breast-feeding should be promoted as an important intervention in the control of diarrhoea / Health Studies / M.A. (Nursing Science)

No description available.

Thesis (MScAgric)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Veal production is a specialised form of calf rearing in which calves were traditionally raised on all-liquid diets. The early weaning of calves onto concentrated diets provides an economically viable alternative rearing method with comparable calf performance. The emphasis in meat production has shifted to the production of lean meat, therefore the deposition of protein instead of fat has become a priority. The optimum level of dietary crude protein for growing calves is well established. Very little, however, is known about the influence of protein degradability in the diet of young ruminants. Recommendations by the NRC are derived from data obtained using lactating dairy cows. The aim was to obtain data on which recommendations for the level of degradable protein in starter and finisher diets for calves could be based. Two experiments were conducted to examine the effect of different levels of dietary crude protein degradability in starter and finisher calf diets on veal calf performance. In both experiments Holstein bull calves were 3 - 10 days of age at the onset, weaned at 4 weeks of age and slaughtered at 20 weeks of age for veal. In Experiment 1 calves were randomly assigned to one of three treatments: low (LO), medium (MD) and high (HO) rumen degradable protein. Calves received a starter diet up to 11 weeks of age and finisher diets from week 12 - 20. In Experiment 2 calves received a starter diet either high or low in rumen degradable protein up to 10 weeks of age. In the finishing period (week 11 - 20) both the low and high groups were again divided into a low and high group, resulting effectively in 4 treatments, viz. LL, LH, HL and HH. The diets in both experiments were formulated to be iso-nitrogenous and iso-caloric, differing only in rumen undegradable protein content within periods and. respective experiments. Body weight gain, feed intake and feed conversion efficiency data for the preweaning, starter, finishing and total experimental period was compared between treatments. There were no significant differences for feed intake, body weight gain or feed efficiency in the starter period of both experiments between treatments. In the finishing period of Experiment 1 the average daily gain for the LO treatment was significantly higher than for the HO treatment, with the MD treatment having an intermediate value. The feed conversion ratio (FCR) for the LO treatment was also significantly better than for the other two treatments. In Experiment 2 the FCR tended (P = 0.0984) to differ between treatments in the finishing period. Calves from the LL and HL treatments had a more favourable FCR than calves from the LH treatment. The HH treatment had an intermediate FCR. According to these results crude protein degradability appears to have an effect on the FCR in the finishing period. The lack of response to higher levels of undegradable dietary protein in calves younger than 10 weeks may be due to underdeveloped rumen functions and it seems possible for high degradable protein to escape degradation to a higher extent than at a later age. In a third experiment, Holstein bull calves and Holstein cows were used to determine and compare the dry matter and crude protein degradability of the four calf diets used in Experiment 2. Rumen VFA concentrations, pH level and NH3-N concentrations were measured for the cannulated Holstein calves to evaluate the level of rumen metabolic maturity of growing calves. Five Holstein bull calves were ruminally cannulated at 6 weeks of age. Dry matter and crude protein degradability were determined once weekly from week 8 - 20 by means of 24 h in sacco incubations. Three ruminally cannulated Holstein cows were used to determine the comparable values for mature ruminants. Dry matter and crude protein degradability differed significantly between the low and high degradable diets for both calves and cows. Dry matter and crude protein degradability in calves increased up to 11 and 12 weeks of age respectively, and then appeared to remain constant to week 20. Dry matter and crude protein degradability values of the starter diets were lower for the calves than for the cows, but values were similar for the finisher diets. Rumen VFA concentrations, pH level and NH3-N concentration showed some fluctuation between weeks, but were similar to literature values for mature animals. / AFRIKAANSE OPSOMMING: Titel: Die invloed van verskillende vlakke van proteïendegradeerbaarheid in aanvangs- en afrondingsdiëte op kalfprestasie in 'n kalfsvleisproduksiestelsel. Kalfsvleisproduksie is 'n gespesialiseerde grootmaakstelsel wat tradisioneel alleenlik op vloeistofdiëte gebaseer was. 'n Stelsel waar kalwers vroeg gespeen word en 'n volledige aanvangs- en afrondingsrantsoen ontvang, bied 'n alternatiewe metode wat ekonomies lewensvatbaar is en vergelykbare kalfprestasie tot gevolg het. Die klem in vleisproduksie het verskuif na die produksie van maervleis. Die neerlegging van proteïen in plaas van vet het dus 'n prioriteit geword. Die optimale vlak van dieetproteïen vir groeiende kalwers is deeglik nagevors. Baie min is egter bekend oor die invloed van proteïendegradeerbaarheid in die dieet van jong herkouende diere. Aanbevelings deur die NRC is afkomstig van data verkry van studies met melkproduserende koeie. Die doel was om data te bekom waarop aanbevelings vir die vlak van degradeerbare proteïen in aanvangs- en afrondingsdiëte vir kalwers gegrond kan word. Twee eksperimente is uitgevoer om die invloed van verskillende vlakke van proteïendegradeerbaarheid in aanvangs- en afrondingsdiëte op kalfprestasie in 'n kalfsvleisproduksiestelsel te ondersoek. Holstein bulkalwers was 3 - 10 dae oud met die aanvang van beide eksperimente, is gespeen op 4 weke ouderdom en op 20 weke ouderdom vir kalfsvleis geslag. In Eksperiment 1 is kalwers ewekansig aan een van drie behandelings toegewys: lae (LO), medium (MD) en hoë (HO) rumen degradeerbare proteïen. Kalwers het tot op 11 weke ouderdom aanvangsdiëte ontvang, terwyl afrondingsdiëte vanaf 12 - 20 weke ouderdom aangebied is. In Eksperiment 2 het kalwers tot op 10 weke ouderdom "n dieet wat óf hoog óf laag in rumen degradeerbare proteïen was, ontvang. In die afrondingsperiode (week 11 - 20) is die lae en hoë groepe elk vervolgens in "n lae en hoë groep verdeel wat effektief tot 4 behandelings gelei het, nl. LL, LH, HL en HH. Die diëte in albei eksperimente was geformuleer om iso-nitrogenies en iso-kalories te wees. Slegs die rumen degradeerbare proteïeninhoud het tussen die onderskeie diëte binne "n bepaalde periode en eksperiment verskil. Gewigstoename, voerinname en voeromsettingsdoeltreffendheid vir die voorspeense-, aanvangs-, afrondings- en totale eksperimentele periode is tussen behandelings vergelyk. In beide eksperimente is geen betekenisvolle verskille gedurende die aanvangsperiode waargeneem t.o.v. voerinname, massatoename en voeromsettingsdoeltreffendheid (VOD) nie. In die afrondingsperiode van Eksperiment 1 was die gemiddelde daaglikse massatoename van die LO behandeling betekenisvol hoër as dié van die HO behandeling, terwyl die MD behandeling "n intermediêre waarde gehad het. Die VOD vir die LO behandeling was ook betekenisvol beter as vir die ander twee behandelings. Die VOD in die afrondingsperiode van Eksperiment 2 het geneig (P = 0.0984) om te verskil tussen behandelings en kalwers van die LL en HL behandelings het "n meer gunstige VOD as kalwers van die LH behandeling gehad. Die HH behandeling het "n intermediêre VOD gehad. Volgens die resultate van hierdie eksperimente het proteïendegradeerbaarheid in kalfrantsoene waarskynlik "n invloed op VOD in die afrondingsperiode. Die gebrek aan respons as gevolg van hoër insluitingsvlakke van nie-degradeerbare proteïen in die rantsoen by kalwers jonger as 10 weke kan moontlik toegeskryf word aan onderontwikkelde rumenfunksies. Dit blyk moontlik te wees dat die hoë degradeerbare proteïenfraksie by jonger kalwers rumendegradering in "n hoër mate as op "n latere ouderdom vrygespring het. In "n derde eksperiment is Holstein bulkalwers en Holstein koeie gebruik om die droëmateriaal- en proteïendegradeerbaarheid van die vier diëte wat in Eksperiment 2 gebruik is, te bepaal en te vergelyk. Rumen WS-konsentrasies, pH-vlak en NH3-Nkonsentrasies is vir die kalwers gemeet om die vlak van metaboliese rumen volwassenheid van groeiende kalwers te evalueer. Vyf Holstein kalwers is op 6 weke ouderdom ruminaal gekannuleer. Droëmateriaal- en proteïen-degradeerbaarheid is een maal per week vanaf week 8 - 20 deur middel van 24 h in sacco inkubasies bepaal. Drie rumen-gekannuleerde Holstein koeie is gebruik om die vergelykbare waardes van volwasse herkouers te bepaal. Droëmateriaal- en proteïendegradeerbaarheid het betekenisvol tussen die lae en hoë degradeerbare diëte vir beide die kalwers en koeie verskil. Droëmateriaal- en proteïendegradeerbaarheid by die kalwers het tot op 11 en 12 weke ouderdom, onderskeidelik, verhoog en daarna tot week 20 relatief konstant gebly. Die droëmateriaal- en proteïendegradeerbaarheidswaardes van die aanvangsdiëte was laer vir die kalwers as vir die koeie, maar die waardes vir die afrondingsdiëte was eenders. Rumen WS-konsentrasies, pH-vlak en NH3-N-konsentrasies het In mate van fluktuasie tussen weke getoon, maar was soortgelyk aan literatuurwaardes vir volwasse diere.

published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy