Ram feretility unaffected by high molybdenum intakes

Abstract

Two trials were conducted to determine the effect of dietary molybdenum (Mo) on the fertility of young rams, when fed for ca 14 weeks to prevent copper (Cu) toxicity. In the first trial, the sexual development of young weaner rams receiving 38 mg Mo/kg DM (Mo group) was compared to that of a control group receiving no Mo. Both groups reached puberty at the same body mass. Although the mass of the testes of the rams in the control group was lower (P < 0,05) than that of the Mo group at slaughter, testicular mass, expressed as a percentage of warm carcass mass, did not differ between treatments. The control group showed a lower degree of spermatogenesis, expressed as the percentage tubules in the testes with spermatozoa, than rams fed Mo. This was assumed to be due to the lower body and testicular mass of the control group at slaughter. No histological evidence of testicular degeneration was observed in either group. In the second trial, young sexually-mature rams were fed a diet in which Mo concentration increased from 20 to 65 mg/kg DM during the experimental period. Sulphur (5,4 g/kg DM, Mo + S group) was included in the diet of one group, while the other group received no additional sulphur (Mo group). Although the Mo concentration in the testes of the Mo group was higher (P < 0,01) than in that of the Mo + S group, no differences between treatments were observed in testicular mass or in any of the measurements of fertility in the rams.

Twee proewe is uitgevoer om die invloed van molibdeen (Mo) in die dieet op die vrugbaarheid van jong ramme vas te stel wanneer hoë vlakke Mo vir ongeveer 14 weke gevoer is om kopervergiftiging te voorkom. In die eerste proef is die geslagsontwikkeling van jong, speenoud-ramme wat 38 mg Mo/kg DM in hulle rantsoene ontvang het (Mo-groep), vergelyk met 'n kontrolegroep wat geen addisionele Mo ontvang het nie. Albei groepe het puberteit op ongeveer dieselfde liggaamsmassa bereik. Alhoewel die testes van die kontrolegroep met slagting ligter (P < 0,05) as dié van die Mo-groep was, het testesmassa, bereken as 'n persentasie van warm karkasmassa, nie tussen behandelings verskil nie. Die kontrolegroep het 'n laer voorkoms van spermatogenese, uitgedruk as persentasie spermbuise in die testes met sperms, as die Mo-groep gehad. Dit kan moontlik toegeskryf word aan die ligter liggaams- en testesmassas van die kontrolegroep met slagting. In geen groep is histologiese aanduidings van enige degenerasie van die testes waargeneem nie. In die tweede proef het jong, seksueel-volwasse ramme 'n rantsoen hoog in Mo ontvang. Die Mo-vlak is tydens die proef vanaf 20 tot 65 mg/kg DM verhoog. By die rantsoen van een groep is 5,4 g swael (Mo + S-groep) per kg DM gevoeg, terwyl die ander groep (Mo-groep) geen ekstra swael ontvang het nie. Alhoewel die Mo-konsentrasie van die testes van die Mo-groep hoër (P < 0,01) as dié in die Mo + S-groep was, is geen verskil tussen behandelings in testesmassa of in enige gemete maatstaf van vrugbaarheid by die ramme waargeneem nie.

Keywords: Copper, fertility, molybdenum, rams, sexual deveolopment, sheep.