Greyling, J. P. C.Schwalbach, L. M. J.Theron, Orion2017-05-082017-05-082001-12http://hdl.handle.net/11660/6184English: A study to evaluate the effect of season (ambient temperature, daylight length and relative humidity) and nutrition on the reproductive potential and sexual characteristics of young Boer goat bucks was carried out between June (winter) and November (spring), 2000. This study was carried out at the University of the Free State campus in Bloemfontein, South Africa. Twelve Boer goat bucks with a mean initial age of 12 months were used in this study. These bucks were divided into two similar experimental groups, with regard to body weight. A high nutritional plane diet was randomly allocated to one group (Group H) and a low nutritional plane diet was allocated to the other group (Group L). The total mixed diet based on Themeda triandra (Red grass) summer hay, supplemented with maize meal, molasses, HPK 40, HPK 60 and lucerne at two different nutritional levels (High and Low) was given ad lib to the two respective experimental groups. Prior to the observation period, all the bucks were subjected to a prescribed diet for adaptation, for a period of 4 weeks. Then 2 weeks prior to the observation period of this trial, each group received their respective treatment diets. During these 6 weeks, the experimental bucks were trained for semen collection with the aid of an artificial vagina. Apart from the different nutritional management, both groups were housed and managed under similar conditions. Semen samples from each buck were collected by means of an artificial vagina. Semen was collected twice weekly throughout the observation period (winter and spring). In order to have a more realistic and accurate measurement an average of the two measurements taken per week (i.e. semen volume, mass motility etc.) was used as a measurement for the respective week. The following semen parameters were evaluated: semen volume, semen colour, mass motility, sperm concentration, percentage live sperm and percentage abnormal sperm. Other sexual characteristics (serum testosterone concentration, scrotal circumference, testes volume, scrotal skin thickness and libido) as well as rectal temperature and body weight was recorded every second week concurrently with semen collection. The environmental factors (ambient temperature, daylight length and relative humidity) were recorded daily. From this study it can be concluded that the semen and sexual characteristics of young Boer goat bucks observed during this trial, were markedly influenced by the week (season) in which semen was collected, although no clear seasonal trend was observed. In general the animals on the higher nutritional plane diet tended to record higher serum testosterone levels and superior semen and testicular characteristics compared to those from the group maintained on a lower plane of nutrition. These differences however were only significant at certain times of the observation period. It can be also concluded that the Boer goat buck maintains its libido and satisfactory potential fertility (testicular characteristics and semen quality) during the winter (outside the natural breeding season). The effect of season and nutrition on the fertility of Boer goat bucks would have been better evaluated, had this study been carried out for all 4 seasons of the year and the nutritional differences been more extreme.Afrikaans: 'n Studie om die effek van seisoen (omgewingstemperatuur, dagliglengte en relatiewe humiditeit) en voeding op die reproduksie potensiaal en geslagseienskappe van jong Boerbokramrne te evalueer, is uitgevoer op die kampus van die Universiteit van die Vrystaat in Bloemfontein, Suid Afrika. TwaalfBoerbokramme met 'n aanvanklik gemiddelde ouderdom van 12 maande is in die studie gebruik. Die ramme is in twee eksperimentele groepe op grond van liggaamsgewig verdeel. 'n Dieet met hoë voedingswaarde is willekeurig aan een groep (Groep H) toegeken en 'n dieet met 'n laer voedingswaarde is aan die tweede groep toegeken (Groep L). Die totale diëet bestaande uit Themeda triandra (Rooigras) somerhooi, met aanvullende mieliemeel, molasse, HPK 40, HPK 60 en lusern (teen verskillende peile) is aan die ramme op 'n ad lib basis gevoer volgens die indeling. Al die ramme het vir 4 weke lank 'n aanpassingsdieet ontvang en 2 weke voor die aanvang van die eksperiment het elke groep sy respektiewelike dieet ontvang. Gedurende die 6 weke aanpassingsperiode is die diere geoefen om die kunsvagina vir semen kolleksie te gebruik. Beide groepe is onder dieselfde omstandighede gehuisves en bestuur, met die enigste verskil dié in die voedingsbestuurspraktyk. Semenmonsters is m.b.v 'n kunsvagina gekollekteer. Semen is twee maal per week gedurende die observasie tydperk (winter tot lente) gekollekteer. Die gemiddelde waarde van twee monsters per week (bv. semenvolume, sperm motiliteit ens.) wat gebruik is as metings, is geneem om 'n meer realistiese en akkurate meting te verkry. Die volgende semenparameters is ge-evalueer: semenvolume, semenkleur, spermmotiliteit, spermkonsentrasie, persentasie lewendige en abnormale sperme). Ander geslagseienskappe (serumtestosteroon konsentrasie, skrotumomvang, testesvolume, skrotum veldikte en libido) sowel as rektale temperatuur en liggaamsgewig is elke tweede week tesame met semenkolleksie gemeet. Die omgewingsfaktore (omgewingstemperatuur , dagliglengte en relatiewe humiditeit) is daagliks gemonitor. Vanuit die studie kan die gevolgtrekking gemaak word dat semen- en geslagseienskappe in jong Boerbokrarnme wat gedurende die studie genoteer IS, beduidend beïnvloed is deur die week (seisoen) waartydens semen gekollekteer is, alhoewel geen seisonale tendens waargeneem is nie. Oor die algemeen was die tendens dat diere op 'n hoër vlak van voedingswaarde dieet, hoër testosteroonvlakke en semeneienskappe getoon het vergeleke met die groep wat 'n dieet op 'n laer energievlak ontvang het. Die verskille waargeneem was slegs betekenisvol tydens sekere tye in die observasieperiode. Die gevolgtrekking kan gemaak word dat die Boerbokramme 'n bevredigende vrugbaarheid potensiaal en libido gedurende die winter (buite die natuurlike teelseisoen) gehandhaaf het. Die effek van seisoen en voeding op die vrugbaarheid van Boerbokrarnme sou waarskynlik beter evalueer kon word, indien die studie oor al 4 seisoene van die jaar kon duur en die voedingswaarde verskille van die twee diëte ook meer prominent was.enGoats -- South AfricaGoats -- BreedingGoats -- Feeding and feedsDissertation (M.Sc.Agric. (Animal Science))--University of the Free State, 2001DissertationUniversity of the Free State