Barnard, J.P.

le Roux, P.J.

English

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THE EFFECT OF HETEROSEXUAL CONTACT ON LIBIDO ANDMATING DEXTERITY IN KARAKUL RAMSNeudam College of Agriculture, Windhoek, S. W.A. and Gellap-ost experimental farmKeetmanshoop, S. W.A.OPSOMMING: DIE EFFEK VAN HETEROSEKSUELE GESLAGSVERMENGING OP LIBIDO EN DEKBEHENDIGHEID BY KARAKOEL-RAMMEKarakoel ramlammers is na speen in drie groepe verdeel en soos volg behandel: Groep A: Totaal geiSoleer van ooie; Groep B: By ooievanaf speen tot 9 maande en daarna geiiloleer; Groep C: Geiiloleer van ooie tot 9 maande en daarna by ooie. Op 18 maande ouderdom isdit'ramme ingekraal en paarsgewys getoets by'n bronstige ooi ten einde 'n rangorde van libido te bepaal. Daarna is elke ram vir 10 minute en met ~herhalings by 'n bronstige ooi in 'n 3 x 3 mkraal gebring ten einde libido, dekbehendigheid en die tyd tot kopulasie asook totale kopulasie tenoteer. Die ramme wat vir die hele periode van ooie geiiloleer was het in alle opsigte die swakste gevaar en slegs 44 %teenoor die 88 en 100 %. re-spektiewelik in Groepe B & C, het enigsins in die ooie beiang gestel. In geval van die groep C ramme is verder waargeneem dat hulle groeitempoaansienlik toegeneem het na introduksie van ooie op 9 maande. Die moontlikheid dat ges1agvermenging 'n verhoogde testosteroon en/of groei-hormoonafskeiding tot gevolg kon gehad het, is genoem. Die gevolgtrekking is gemaak dat isolasie van ramme na speen ongewens is en dat he-teroseksuele geslagsvermenging voor of na puberteit van groot praktiese belang mag wees. 'n Eenvoudige toets vir libido mag ook bydra om af-wykende ramme op 'n vroee stadium op te spoor en uit te skakel.Karakul ram lambs were divided into three groups after weaning and treated as follows: Group A: Total isolation; Group B: Contactwith ewes until 9 months and then isolated; Group C: Isolated from ewes until 9 months and then allowed contact. At 18 months the ramswere penned and then tested in pairs on oestrous ewes to establish a rank order for libido. SUbsequently all rams were introduced individuallyfor 10 minutes in a sequence of 5 replications to oestrous ewes in a 3 x 3 m pen. Libido, mating dexterity as well as the time lapse to ftrst co-pulation and total copulations were recorded. Totally isolated rams reacted poorly and only 44 %compared with 88 and 100%respectively ofthe rams in Groups B & C showed normal mating behaviour. Rams in Group C experienced a growth surge after introduction of ewes at 9months of age and the possibilities of sexual contact resulting in greater testosterone and/or growth hormone release, is discussed. It was con-cluded that the practice of isolation of ram lambs after weaning is detrimental to normal sexual behaviour and that hetero-sexual contact prioror subsequent to puberty could be of practical importance. A simple libido test to eliminate sexually inhibited rams at an early stage is recom-mended.The literature on sexual behaviour of rams has beencomprehensively reviewed by Pretorius (1972). Reportsfrom overseas (Banks, 1964; Hulet, 1966; DYrmundsson &Lees, I972) and South Africa (Marincowitz,Pretorius&Herbst)1966; Pretorius, 1967) indicate that it is not uncommonfor rams previously reared in isolation of ewes to becomesexually inhibited and/or inactive for certain periods afterbeing introduced to oestrous ewes. According to Kagen &Beach (1953), heterosexual contact at a relatively earlystage of development is important for normal sexual beha-viour and Banks (1964) and Pretorius (1967) concludedthat the puberal phase is of special importance. However,no data on the effects of isolation of rams during differentstages of sexual development on adult behaviour are avail-able. Consequently. the present experiment was executedto determine the effects of total isolation as well as that ofheterosexual contact during the pre· -and post-puberalphase on libido, mating dexterity and the occurrence ofhomosexuality in Karakul rams.weaned at a mean age of 68 days and randomly allotted to3 treatment groups. Treatments were as follows:Group A:Group B:Totally isolated from ewes.Heterosexual contact from weaning until9 months of age and then isolated.Isolated until 9 months of age and thenallowed heterosexual contact.The rams were kept on natural veld grazing in campsrotated every fortnight. A lick consisting of 40% bonemeal:40% salt: 20% fishmeal, was supplied ad libitum. Ewes in·troduced to Groups B & C were kept with the group forabout 6 weeks whereafter they were slaughtered, inspectedfor pregnancy and replaced by fresh ewes. The followingdata were recorded:1. Observation on behaviour of rams were made fromtime to time throughout the experimental periodwhich lasted from 16.7.71 to 4.11.72.Birth and weaning mass as well as body mass at month-ly intervals after weaning, were recorded.3. At 18 months of age all the rams were penned andallowed an adaptation period of 14 days. Prior tocommencement of testing, one ram from each groupwas randomly chosen and these three rams allowedto compete in pairs to serve an oestrous ewe untilla rank order of libido for each group was established.The dominant ram in every group of three was allot-ted a 3 and so forth whereas rams with the same scorewere allotted the mean of the two scores. These datawere pooled for all the rams in a group and a meanorder of libido for every group was computed.4. Subsequent to the libido test the rams were introdu-ced individually to an oestrous ewe in a 3 x 3 m pen.Oestrus was induced by injection of stilboestrol-di-propionate. All rams were tested with regard to thetime interval to the first mount as well as the totalnumber of attempts. In addition the time lapse tofirst intromission and ejaculation as well as the totalnumber of complete matings were recorded. All ramswere allowed 5 introductions lasting 10 minutes withat least 8 h intervals. Any ram which showed no in-terest in the ewe after 5 minutes was removed fromthe pen.5. Two days subsequent to the individual tests, semenwas collected by electro~timu1ation and evaluated asdescribed by Starke (1949).6. Arithmetic means of the data were calculated and ana-lysed by analysis of variance (Snedecor & Cochran,1967).The growth curves for the three groups are shown inFig. 1. An interesting feature of these curves is the growthsurge experienced by Group C after the introduction ofewes at 9 months of age. The mean mass at weaning waswithin 2 kg of each other whereas the final masswas highlysignificantly (P< 0,01) in favour of Group C. Apparentlypost-puberal sexual stimulation resulted in greater releaseof either testosterone, acting anabolic and/or growth hor-mone.Signsof sexual behaviour involvingattempts to mountother lambs, or ewes in the case of Group B, were noted atan early age of between two and three months. Fraser(1968) described the occurrence of prepuberal mounting ofboth hetero- and homosexual nature whereas (Symington(1961) and Louw & Joubert (1964) pointed out that clearsigns of libido may be observed in the ram lamb some timebefore puberty.In the present study the first successful copulations,as deduced from slaughtered ewes and the development ofthe embryo, occurred at 144 days of age (Group B). This•• •I•••••••••••__ Iagrees with the finding of DYrmundsson & Lees (1972)who recorded an age at fmt mating of 142 days for ClunForest ram lambs.Clear cut differences in libido and mating dexteritywere established between rams with highly significant(P<0,01) better scores for rams in Groups B & C.Group Arams scored a mean of 2,2 out of a 5 maximum for libidowhich was highly significantly (P<0,01) less than the 4,7and 4,8 respectively recorded by rams of groups B and C.The mean scores for a sequence of 5 introductions tooestrous ewes for time to the first mount, time to the frrstcopulation and total copulations within 10 minutes aregiven in Table 1. These data indicate a highly significant(P< 0,01) quicker reaction of rams in those groups whichhad had previous cootact with ewes (Groups B & C). More-over, these rams also served more ewes per unit time com-pared with those in the isolated group. The relatively lowpercentage (44%)of rams in the isolated groups which wereat all interested in oestrous ewes (Table I), when compared,with the 88 and 100%respectively in Groups B & C, furtherreflects the inhibiting effects of total isolation on sexualbehaviour. The isolated rams, when introduced to a ewewere generallyvery nervous and easily ftightened or distrac-ted by noise or movement, whereas the rams of groups Band C were immediately attracted to the ewe. It was obvi-ous that in the latter cases the sex drive was strong enoughto overcome any initial nervousness. The suggestions ofBanks (1964) and Pretorius (1967), that the practice ofrearing rams is isolation from ewes from the time of wean-ing could effect sexual behaviour patterns, are confirmedby the present results.Most observations on sexual behaviour of rams illus-trate that sexual behaviour patterns are learnt with matingdexterity improving gradually as the number of sexual en-counters increased (Dyrmundsson, 1973). However, in thepresent study only one of the four active rams in the iso-lated groups, learned by repetition - the other three beingactive from the start. In Group B all the active rams (8/8)mated at the first introduction whereas only one of the 9Table ITtme to tint attempt, to sz,ctesful opulation and total ranmbq of copulations(Mean, ̂ S.E'. & rerye) by mms in paiods of I0 mtruntes (Mean rcore for 5 replications)GroupNo (  zo;activeTirrc in minutes tofirst morurtTinrc in minutes tofirst copulationTotal copulations inl0 minutesA 4 (+4) 6,27 x 1,45 (010-10,0) 692 t 1,49 (012-10,0) 1,02 1050 (O - 5)B 8 (8E) l3l r 1,03 (03-l0p) 1,57 + 1,06 (06-10,0) 2,56 ! oJ8 (0 - S1c e (100) 0,89 r 0,66 (03-10,0)P<0,01l , l7 + 0J8 (06-10,0)P<0,012,69 tO39 (l - 6)P<0,01-ltctirr rams in Group C became intercsted after soqucntialintrodustion to euns. Apparently rams of groupe B & C,having had previous hctsrccxual curtact, wore skeady cx-pcrienced whcreas the isolated rams urcre pobably inhibi-tcd to sucJr a degree by lack of contact that evcn rcpoatedintrodustio'B to ewes did not rcgult in norrral beheviour.Howewr, sequontial introduction to eu/e$, u ilustratod inFigp. 2 & 3, subetantiatly improved mating dcxterity in ac'tive rarns if assesscd respcctively in torms of thc tirr lapreto copulatio, ttle totd number of copulatims rs woll rtbe rccoltry period botweelr copulatiots.l l t a tffiFrg.2 The effect of sequenfiul int'ductions of rams tooestnout rlwes on the time lopse to copulationThe el\ect of sequential innodtctions of rons tooestrout euas on the recovery Wiod between,rutings urd totol nutings within I0 minutesl!I3F2 3lrGoisfiF8. 3t73Apart from a tendency to nose the udder region ofewes which was very noticeable in the isolated group, noclear cut homosexual behaviour was observed in any of therams. The motility, density and proportion of live spermdid not differ between the three groups of rams.It is concluded that the rearing of ram lambs in iso-lation of ewes is an undesirable practice which could adverse-ly affect sexual behavioural patterns. Heterosexual con-tact prior or subsequent to puberty seems therefore of theutmost importance and should be implemented in sheephusbandry systems. Furthermore the application of asimple libido test at 10 to 12 months of age or prior totheir first mating season could probably serve to eliminateshy servers and rams with poor libido. According to Mattner,Braden & George (1973) the failure of the development ofnormal sexual behaviour could be genetically controlledand if such rams are located at an early stage it could pro-bably substantially improve lambing percentage in sheep.The observation that sexual contact resulted in a growthsurge requires further elucidation.BANKS, EM., 1964. Some aspects of sexual behaviour in domestic sheep, Ovis aries. Behaviour 23, 249.DYRMUNDSSON, O.R., 1973. Puberty and early reproductive performance in sheep. II. Ram lambs. Anim Breed Abstr. 41,9,419.DYRMUNDSSON, O.R. & LEES, J .L., 1972. A note on the mating ability in Clun Forest ram lambs. Anim Prod. 14,2,259.FRASER, A.F., 1968. Reproductive behaviour in ungulates. London: Academic Press.HULET, C.V., 1966. Behavioural, social and psychological factors affecting mating time and breeding efficiency in sheep. J.Anim. Sci. 25, Supp!., 5.KAGEN, J. & BEACH, F .A., 1953. Effects of early experience on mating behaviour in male rats. J. Compo Physiol. 46,204.LOUW, D.FJ. & JOUBERT, DM., 1964. Puberty in the male Dorper sheep and Boer goat. S. Afr. J. agric. Sci. 7,509.MARINCOWlTZ, G., PRETORIUS, P.S. & HERBST, S.N., 1966. Dominance in sexual behaviour and mating dexterity inMerino rams.S. Afr. J. agric. Sci. 9,971.MATTNER, P.E., BRADEN, A.WR. & GEORGE, JM., 1973. Studies in Flock mating of sheep. 5. Incidence, duration andeffect on flock fertility of initial sexual inactivity in young rams. Aust. J. expo Agric. Anim. Husb. 13, 60, 35.PRETORIUS, P.S., 1967. Libido and mating dexterity in rams reared and kept in isolation from ewes. Proc. S. Afr. Soc.Anim. Prod. 6,208.PRETORIUS, P.S., 1972. Mating behaviour of rams. A review.J1 S. Afr. vet med. Ass. 43(2), 155.SNEDECOR, G.W. & COCHRAN, W.G., 1967. Statistical methods. Ames, Iowa State University Press.STARKE, N.C., 1949. The sperm picture of rams of different breeds an indication of their fertility. Onderstepoort J. vet.Sci. 22,415.SYMINGTON, R.B., 1961. Studies on the adaptibility of three breeds of sheep to a tropical environment modified by altitude.VII. Sexual activity in relation to age of ram. J. agric. Sci. Camb. 56, 179.

The effect of heterosexual contact on libido and mating dexterity in Karakul rams

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The effect of heterosexual contact on libido and mating dexterity in Karakul rams

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