An evaluation of reproductive performance of horro cattle in Ethiopia

Abstract

English: A study consisting of 2 phases was undertaken to evaluate the reproductive performance in female and male Horro (Bos indicus) cattle at the Bako Agricultural Research Center, Ethiopia. In the first part of the study the female reproductive indicators such as age and weight at puberty, age at first conception and first calving, post partum anoestrous interval, post partum period, intercalving period, growth from birth to 24 months of age, abortion rate as well as the herd mortality rate were evaluated using herd records collected between 1974 and 2001 at the Research Center. In the second part of the study, post partum live weight changes of cows, their serum progesterone profiles, the seasonal changes in bull semen, testicular characteristics and testosterone profiles were recorded in tests conducted between February 2001 and January 2002 at the same center. General linear model (GLM) procedures of SAS (SAS, 1994) were used to analyse the data. The least square means were separated using Duncan's multiple range test. The overall least square mean age and weight at puberty, 1st conception and I" calving for heifers was 39.4 months, 202.9 kg, 50.1. months, 226.7 kg, 58.7 months and 259.2 kg respectively. The age at puberty, l" conception and 1st calving was not affected by season of birth and birth weight. The age at 1st conception and 1st calving significantly (P<0.05) affected the year of birth. Differences were recorded for age at 1st conception and 1st calving between the years monitored. The mean weight at puberty, conception and calving rates were not affected by the season of birth and birth weight. The year of birth did not affect the weight at puberty, but significantly (P<0.05) affected the weight at I" conception and 1st calving. Differences were recorded for body weight between the observation years for weight at 1st conception and 1st calving. The overall least square means for the post partum anoestrous interval and post partum period were 77.2 and 117.5 days respectively. The season (P<0.05) and year of calving (P<0.01) significantly affected the post partum anoestrous interval. The shortest post partum anoestrous interval (72.5 ± 3.4 days) was recorded during the wet season (May to September), while the longest (81.7 ± 2.9 days) period was recorded in the dry season (October to April). Differences were recorded between years for the post partum anoestrous interval from 1977 to 2001. The season of calving, calf birth weight and sex of the calf did not affect the post partum period, but year of calving (P<0.01) played a significant role. Differences were recorded between years for the post partum period from 1977 to 2001. Sex of the calf significantly (P<0.05) affected the post partum anoestrous interval with dams bearing male calves demons,trating a longer period. The overall least square mean intercalving period and gestation length recorded, were 472 and 283 days respectively. Intercalving period was not affected by the season of calving, sex of the calf and calf birth weight. However the year of calving (P<0.01) and parity (P<0.05) significantly affected the intercalving period. Differences were recorded between years for intercalving period. The longest intercalving period (503.7 ± 8.8 days) was recorded during the second parity, compared to 3rd, 4th, 5th and 6th parities (469.0 ± 9.7, 449.2 ± 11.2, 468.6 ± 13.3 and 456.8 ± 16.4 days, respectively). Significant differences were recorded between years regarding gestation length, but no significant differences were observed between season (wet or dry) for gestation length. Sex of the calf significantly (P<0.05) affected gestation length with cows bearing bull calves having a longer gestation period. Post partum live weight changes and serum progesterone concentrations in cows indicated that cows that calved during the dry season lost more weight. From the total number of cows that calved during the dry season only 20% of them became pregnant within 90 days post partum, compared to 60% for cows that calved during the wet season. The overall least square mean serum progesterone (dry and wet season) concentration was 6.1 ng/ml and this was significantly (P<0.01) affected by season of calving and the cow body weight at calving. The mean progesterone level during the wet season (May to September) was higher (8.5 ± 0.8 ng/ml) and that during the dry season (October to April) was lower (2.8 ng/ml) . For the progeny, the overall least square mean birth, 3, 6, 12, 18 and 24 month of age body weights, pre- and post weaning ADG for Horro cattle were 18.4, 48.9, 68, 87.5, 109.7 kg, 275 g/day and 130.9 g/day, respectively. The birth weight of the calves was not affected by season of birth, but sex of the calf (P<0.01) and year of birth (P<0.05) affected birth weight. Male calves were generally 11.6% heavier than their female counterparts at birth. Differences on birth weight were recorded between years. The 3 and 6 month weights were not affected by the sex of the calf, but season (P<0.05) and year of birth (P<0.01) significantly affected body weight at 3 months. Calves born in the wet season recorded the highest body weight at 3 months of age, compared to those born in the dry season. Differences were recorded between years from 1977 to 2001 regarding the weight at 3 months of age. The body weights at 12, 18 and 24 months were significantly (P<0.05) affected by the sex of the calf, season of birth and calf birth weight. Female calves were heavier at these ages compared to their male counterparts. Heavier calves at birth and those born in the wet season recorded the highest weights at 12, 18 and 24 months of age. Differences were recorded between the survey years in 12 and 18 months weight from 1977 to 2000. The pre-weaning ADG was not influenced by the sex of the calf or the season of birth, but was influenced by the year of birth. Differences were recorded between years in pre-weaning ADG. Post weaning ADG was not affected by sex of the calf, but season of birth significantly (p< 0.05) affected post weaning ADG. Calves born in the wet season recording the highest post weaning ADG. In the second part of this study the male reproductive performance and sexual characteristics of Horro (Bos indicus) (n=32) bulls, with an average initial body weight of 211 kg and age of approximately 6 years were evaluated. The bulls were divided into two treatment groups. One group was given a supplementary concentrate at a rate of 1.5 kg/day and the second group served as the control and received no supplementation. The observation period lasted for 50 weeks. Semen was collected every two weeks by means of electric stimulation with the aid of an electro-ejaculator. General linear model (GLM) procedures of SAS (SAS, 1994) were used to analyse the data. Semen and testicular characteristics, body weight and serum testosterone concentration were recorded during this period. The following semen parameters were evaluated: semen volume, semen color, mass motility, sperm concentration, percentage live sperm, percentage abnormal sperm and semen pH. Other male sexual characteristics evaluated were serum testosterone concentration, scrotal circumference, testis volume, scrotal skin thickness and libido as well as body weight every second week, concurrent with semen collection. In general the bulls from the supplemented group tended to have higher quality semen characteristics. Three colour types of ejaculates were observed, namely, creamy, milky and watery. Semen from the supplemented group tended to have a more creamy colour, when compared to the non-supplemented group. There was a general tendency for the bulls from the supplemented group to maintain a higher sperm motility score during the trial period - ranging from 2.6 ± 0.2 to 3.6 ± 0.2, compared to the 1.7 ± 0.2 to 3.0 ± 0.3 of the control group. Sperm concentration in the supplemented group remained higher compared to that of the bulls in the non-supplemented group. The percentage of abnormal sperm (total abnormalities, head, mid-piece and tail) remained lower in the supplemented group than the non-supplemented group. Semen pH remained constant around 6.8 for most of the observation period. Libido score for both supplemented and control group remained constant (1.5 ± 0.3 to 3.8 ± 0.2 and 1.4 ± 0.2 to 3.8 ± 0.2, respectively). The scrotal circumference measured during the trial period for the supplemented and control group was 28.8 ± 0.5 to 32.8 ± 0.2 cm and 28.9 ± 0.5 to 32.9 ± 0.2 cm respectively. Scrotal circumferences were not influenced by nutritional supplementation. Scrotal skin thickness was also not influenced by nutritional supplementation, but time (weeks) and the time x treatment interaction influenced scrotal skin thickness. As the trial progressed, the bulls increased in age and so the fat deposition in the scrotum increased. Testis length increased similarly in both treatment groups. A minimal increase in testis length was recorded over the 50 week period. The testis volume in both supplemented and control group increased gradually from the onset of the trial (week 0) to the end of the observation period (week 50). Significant differences were observed between the supplemented and control group regarding testis volume during certain weeks only. The mean body weight in both groups (supplemented and control) increased steadily from the onset of the trial to the end of the experiment. Bulls from the supplemented group gained on average more compared to the non-supplemented group. Serum testosterone levels of bulls collected during the dry season (October to April) were higher (911 ± 35.3 ng/dl) than during the wet season (May to September) (768.6 ± 30.9 ng/dl). Although not significant, bulls from the supplemented group recorded higher serum testosterone levels. Overall, the productive and reproductive performance of Horro cattle (female reproductive and growth) at Bako Research Center has not improved much over the years. Inadequate nutrition and poor management in the herd have been implicated. It is suggested that efforts need to be made to improve the management. The introduction of a limited breeding season to induce early summer, calving is warranted. Calving during the summer (wet) season has advantages in both the reproductive and productive performance of the cows. From the bull reproduction evaluation, it can be concluded that the semen and sexual characteristics observed during the trial are markedly influenced by the time (season) in which semen was collected. In general, the animals on the supplemented group tended to record higher serum testosterone levels and better semen and testicular characteristics compared to the control animals. It would seem that supplementation of breeding bulls is advantageous to their fertility. Further studies on the reproductive and productive characteristics of the Horro breed were recommended.Afrikaans: 'n Studie bestaande uit 2 fases, is onderneem om die reproduksie prestasie van vroulike en manlike Horro (Bos indicus) beeste te evalueer by die Bako Landbou Navorsingssentrum in Ethiopië. In die eerste deel van die studie is vroulike reproduksie parameters soos ouderdom en gewig tydens puberteit, ouderdom by 1ste konsepsie en 1ste kalwing, post partum anoestrus interval, post partum periode, interkalf periode, groei van geboorte tot 24 maande ouderdom, aborsie tempo asook die kuddemortaliteit geëvalueer deur van kudderekords gebruik te maak vanaf 1974 tot 2001 by die Navorsingssentrum. In die tweede deel van die studie is die post partum liggaamsgewig veranderinge van koeie, hul serum progesteroon profiele, die seisoensverandering in die bulsemen, testikulêre eienskappe en testosteroon profiele gegenereer uit studies tussen Februarie 2001 en Januarie 2002 by dieselfde sentrum. Die algemene liniëre model (GLM) prosedures van SAS (SAS, 1994) is gebruik om die data te analiseer. Die kleinste kwadraat gemiddelde is verdeelm.b.v .. "Duncan's multiple range test". Die algehele kleinste kwadraat gemiddelde ouderdom en gewig tydens puberteit, l ste konsepsie en lste kalwing in verse was 39.4 maande, 202.9 kg; 50.1 maande, 226.7 kg; 58.7 maande en 259.2 kg, respektiewelik. Die ouderdom tydens puberteit, l ste konsepsie en l ste kalwing is nie geaffekteer deur die geboorteseisoen of geboortegewig nie. Die ouderdom tydens 1ste konsepsie en 1ste kalwing het die jaar van geboorte betekenisvol (P<0.05) geaffekteer. Verskille in die liggaamsgewig is gerapporteer gedurende die jare van observasie t.o.v. gewig met 1ste konsepsie en 1ste kalwing. Die algehele kleinste kwadraat gemiddeld in die post parturn anoestrus interval en post partum periode was 77.2 en 117.5 dae, respektiewelik. Die seisoen (P<0.01) en jaar van kalwing (P<0.01) het die post partum anoestrus interval betekenisvol beinvloed. Die kortste post partum anoestrus interval (72.5 ± 3.4 dae) is gedurende die nat seisoen (Mei tot September) waargeneem en die langste (81.7 ± 2.9 dae) periode gedurende die droë seisoen (Oktober tot April). Verskille in die post partum anoestrus interval is waargeneem gedurende die periode van 1977 tot 2001. Die seisoen van kalwing, geboortegewig en geslag van die kalf het nie die post partum periode geaffekteer nie, maar die jaar van kalwing (P<0.01) het 'n betekenisvolle rol gespeel. Verskille in die post partum periode is waargeneem vanaf 1977 tot 2001. Die geslag van die kalf het die post partum anoestrus interval betekenisvol (P<0.05) geaffekteer met koeie dragtig met bulkalwers wat 'n langer periode gedemonstreer het. Die algehele kleinste kwadraat gemiddelde interkalf- en dragtigheidsperiode waargeneem, was 472 en 283 dae, respektiewelik. Die interkalf periode is nie geaffekteer deur die seisoen, geslag en geboortegewig van die kalf nie. Die jaar van kalwing (P<0.01) en hoeveelste dragtigheid (P<0.05) het die interkalf periode betekenisvol beinvloed. Verskille is deur die jare gerapporteer in die interkalfperiode. Die langste interkalfperiode (503.7 ± 8.8 dae) is waargeneem gedurende die 2de, vergeleke met die 3de, 4de, 5de en 6de dragtigheidsperiodes (469.0 ± 9.7, 449.2 ± 11.2, 468.6 ± 13.3 en 456.8 ± 16.4 dae, respektiewelik). Betekenisvolle verskille IS waargeneem tydens die dragtigheidsperiode, maar geen betekenisvolle verskille is gedurende die dragtigheidseisoen (nat of droog) waargeneem nie. Die geslag van die kalf het die dragtigheidsduur betekenisvol (P<0.05) beinvloed - koeie dragtig met bulkalwers het 'n langer dragtigheidsperiode getoon. Post partum liggaamsgewig veranderinge en serum progesteroon konsentrasies in . koeie het aangetoon dat koeie in die droë kalfseisoen meer.gewig verloor het. Uit die totale koeie wat gedurende die droë seisoen gekalf het, het slegs 20% beset geraak binne 90 dae post partum, vergeleke met 60% koeie wat gekalf het gedurende die nat seisoen. Die algehele kleinste kwadraat gemiddelde serum progesteroon (droë en nat seisoen) konsentraat was 6.1 ng/ml en is betekenisvol (P<0.01) geaffekteer deur die kalfseisoen en die koei se liggaamsgewig tydens kalwing. Die gemiddelde progesteroonvlak was hoër (8.5 ± 0.8 ng/ml) tydens die nat seisoen (Mei tot September) en laer (2.8 ng/ml) gedurende die droë seisoen (Oktober tot April). In die nageslag is gevind dat die algehele kleinste kwadraat gemiddelde vir voor- en naspeen GDT in Horro beeste tydens geboorte, 3, 6, 12, 18 en 24 maande 18.4,48.9, 68, 87.5, 109.7 kg, 275 g/dag en 130.9 g/dag respektiewelik is. Die geboortegewig van die kalwers is nie geaffekteer deur die geboorteseisoen nie maar wel deur die geslag van die kalf (P<0.01) en die geboortejaar (P<0.05). Bulkalwers was oor die algemeen 11.6% swaarder as die verskalwers met geboorte. Verskille in geboortegewig is gedurende die jare gerapporteer. Die 3 en 6 maande liggaamsgewigte is nie deur die geslag van die kalf geaffekteer nie, maar die seisoen (P<0.05) en geboortejaar (P<0.01) het die 3 maande liggaamsgewig betekenisvol beinvloed. Hoër liggaamsgewigte is gerapporteer vir 3 maande oud kalwers wat tydens die nat seisoen gebore is vergeleke met 3 maande oud kalwers wat tydens die droë seisoen gebore is. Verskille is gerapporteer in die liggaamsgewig op 3 maande ouderdom van 1997 tot 2001. Die geslag van die kalf, geboorteseisoen en kalfgeboortegewig het die liggaamsgewigte op 12, 18 en 24 maande betekenisvol (P<0.05) beinvloed. Verskalwers was swaarder op die ouderdomme, vergeleke met bulkalwers. Swaarder kalwers tydens geboorte en kalwers gebore tydens die nat seisoen het die swaarste liggaamsgewigte gerealiseer tydens 12, 18 en 24 maande ouderdom. Verskille in 12 en 18 maande liggaamsgewigte is tydens die opnamejare vanaf 1977 tot 2000 gevind. Die voorspeense GDT is nie deur die geslag van die kalf of the geboorteseisoen beinvloed nie, maar wel deur die geboortejaar. Verskille is gemonitor oor jare t.o.v. voorspeense GDT. Die geslag van die kalf het nie die naspeen GDT beinvloed nie, maar die geboorteseisoen het die naspeen gemiddelde daaglikse toename betekenisvol beinvloed. Die hoogste naspeen gemiddelde daaglikse toename is gerapporteer in kalwers gebore tydens die reënseisoen. In die tweede deel van die studie is die manlike reproduksiepotensiaal en geslagseienskappe van Horro (Bos indicusï (n = 32) bulle met 'n gemiddelde inisiële liggaamsgewig van 211 kg en ± 6 jaar ouderdom geëvalueer. Die bulle is in 2 behandelingsgroepe ingedeel. Een groep is 'n aanvullingskonsentraat teen 'n tempo van 1.5 kg/dag gevoer. Die tweede groep het as die kontrole gedien en het geen aanvulling ontvang nie. Die waarnemingsperiode het vir 50 weke geduur. Semen is elke 2 weke gekollekteer d.m.v. elektriese stimulasie m.b.v. 'n elektro-ejakulator. Die algemene liniêre model (ALM) prosedures van SAS (SAS, 1994) is gebruik om die data te analiseer. Semen en testikulêre eienskappe, liggaamsgewig en serum testosteroon konsentrasie is gemonitor gedurende die periode. Die volgende semen parameters is geëvalueer: semen volume, semenkleur, algehele motiliteit, sperm konsentrasie, persentasie lewende sperm, persentasie abnormale sperm en semen pH. Ander manlike geslagseienskappe soos serum testosteroon konsentrasie, skrotale omtrek, testes volume, skrotale veldikte, libido asook liggaamsgewig is elke tweede week tesame met semenkolleksie geëvalueer. Oor die algemeen het bulle van die behandelde groep beter semeneienskappe getoon. Drie kleurtipes ejakulaat is waargeneem naamlik romerig, melkerig en waterig. Semen van die behandelde groep het geneig om meer romerige te wees as die onbehandelde groep. Die behandelde bulle het oor die algemeen 'n hoër sperm motiliteitstelling gehandhaaf tydens die waarnemingsperiode - variasie tussen 2.6 ± tot 3.6 ± 0.2, vergeleke met 1.7 ± 0.2 tot 3.0 ± 0.3 in die kontrole groep. Spermkonsentrasies in die behandelde groep was hoër, vergeleke met die van bulle van die onbehandelde groep. Die persentasie abnormale sperm (totale abnormaliteite, kop-, middelstuk- en stertabnormaliteite) het laer gebly in die behandelde groep as in die kontrole groep. Semen pH het konstant rondom 6.8 gebly vir 'n groot deel van die observasie periode. Die libido telling in beide die behandelde en kontrole groep het ook konstant gebly (1.5 ± 0.3 tot 3.8 ± 0.2 en 1.4 ± 0.2 tot 3.8 ± 0.2, respektiewelik). Die skrotale omtrek gemeet gedurende die waarnemingsperiode vir die behandelde en kontrole groep was 28.8 ± 0.5 tot 32.8 ± 0.2 cm en 28.9 ± 0.5 tot 32.9 ± 0.2 cm respektiewelik. Die skrotale omtrek asook die skrotale veldikte is nie beinvloed deur voedingaanvulling nie, maar tyd (weke) en 'n tyd x behandeling interaksie het wel die skrotale veldikte bemvloed.· Namate die waarnemingsperiode gevorder het, het die bulle toegeneem in ouderdom en die vetlaag in die skrotum verhoog. Die testeslengte het dieselfde toegeneem in beide behandelingsgroepe. In Minimale groei in testeslengte is waargeneem tydens die 50 week periode. Die testesvolume in beide die behandelde en kontrole groep het geleidelik gegroei van die begin (week 0) tot die einde van die waarnemingsperiode (week 50). Betekenisvolle verskille is tussen die behandelde en kontrole groepe t.o.v. testesvolume (slegs gedurende sekere weke), waargeneem. Die gemiddelde liggaamsgewig vir beide groepe (behandelde en kontrole) het stadig toegeneem van die begin van die waamemingsperiode tot aan die einde van die eksperiment. Bulle van die behandelde groep het oor die algemeen meer in gewig toegeneem vergeleke met die onbehandelde groep. Serum testosteroonvlakke gekollekteer van bulle gedurende die droë seisoen (Oktober tot April) was hoër (911 ± 35.3 ng/dl) as gedurende die nat seisoen (Mei tot September) (768.6 ± 30.9 ng/dl). Alhoewel nie betekenisvol nie, is hoër serum testosteroonvlakke in die behandelde bulle waargeneem. Oor die algemeen het die produksie en reproduksie prestasie in Horro beeste (vroulike reproduksie en groei) by die Bako Navorsingssentrum oor die jare nie verbeter nie. Dit is te wyte aan onvoldoende voeding en swak bestuur van die kudde. Daar word voorgestel dat pogings aangewend moet word om die bestuur te verbeter. Die instelling van 'n vasgestelde kalfseisoen ten einde die indusering van vroeë somerkalwings, is geregverdig. Kalwing gedurende somerseisoen (nat) is voordelig vir beide die reproduksie en produksieprestasie van die koeie. Die gevolgtrekking uit die bul se reproduksie evaluasie, is dat die semen- en geslagseienskappe waargeneem tydens die periode, merkwaardig beinvloed word deur die tyd (seisoen) van semenkolleksie. Oor die algemeen was die diere in die behandelde groep geneig om hoër serum testosteroonvlakke te handhaaf en beter testikulêre eienskappe te toon, vergeleke met die kontrole diere en dit wil voorkom asof aanvullingsvoeding van teelbulle voordelig is vir fertiliteit. Verdere studies oor die reproduksie- en produksie eienskappe in die Horro ras word egter aanbeveel.