Thesis (M.Sc.) Uppsala : Sveriges lantbruksuniversitet.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2006. / Härtill 5 uppsatser.

Ethiopia maintains an extensive livestock population; however, reproductive performance of cattle and their breeding management are unsatisfactory. Currently, the sole diagnostic tool in the country is rectal palpation, which is inaccurate for early pregnancy in cattle. The study assessed reproductive performance and major reproductive problems using questionnaire survey, and evaluated simple, cost-effective alternative monitoring approaches using on-farm diagnostic tools to determine milk and serum progesterone (P4) and evaluate reproductive status. There were 177 dairy farms (range 1-115 cattle per farm) included in the questionnaire survey. Of these, 47 participated in the quantitative determination of P4 and estradiol profiles that used an enzyme-linked immunosorbent assay (ELISA) and in the on-farm diagnostic trial that used qualitative ELISA (Target P4 and Dipstick (P4 Rapid), and the reproductive status of 319 crossbred [Holstein Friesian (HF) X Zebu] dairy cattle was assessed. Questionnaires indicated that heifers in the study area reach puberty at older age and calve late, and cows have long postpartum estrus and calving interval. Anestrus, repeat-breeding, dystocia, retained fetal membranes (RFM), endometritis and abortion as the major reproductive problems in dairy cattle in the study area. Serum, milk, saliva and urine P4 and serum estradiol profiles of cattle at different reproductive status was determined using quantitative laboratory ELISA. High P4 levels was detected in pregnant and diestrus cattle than cattle that were anestrus and in-heat. Estradiol level was higher in cattle that were in-heat than cattle in other reproductive conditions. On-farm P4 ELISA indicated in-heat (estrus) 10 (3.1%), anestrus 77 (24.2%), repeater (follicular cyst) 9 (2.8%), normally cycling 69 (21.6%) and pregnant 154 (48.3%). The field P4 ELISA findings were validated using quantitative laboratory P4 ELISA, and similar results were obtained. The sensitivity and specificity of on-farm and laboratory P4 ELISA tests for diagnosing pregnancy were 88.6 & 99.4% and 98.1 & 100%, respectively. Once reproductive problems were identified using on-farm P4 ELISA and per rectal palpation, along with reproductive history, 122 cattle (75 cows and 47 heifers) were assigned to a 10-day Controlled Internal Drug Release (CIDR) in combination with prostaglandin F2-alpha (PGF2α) and equine chorionic gonadotrophin (eCG) based estrus synchronisation protocol to study the estrus response and conception rate. The overall estrus response and conception rates were 97.5% and 78.3%, respectively, with no significant differences in parity, pre-treatment reproductive status (anestrus or cycling (repeat-breeding/silent-estrus)) and farming system (smallholder vs organised commercial farms). The study has shown high estrus response and conception rate. Hence, this protocol is highly recommended to enhance fertility of dairy cattle in the study area and other regions. Finally, the study has determined the macronutrient composition of milk and assessed the effect of reproductive status, farm (nutritional) management, stages of lactation, parity and breed on milk composition in 246 dairy cows. This consisted of 184 crossbred cows from smallholder (n= 76: 36 non-pregnant and 40 pregnant) and organised commercial dairy farms (n= 108: 62 non-pregnant and 46 pregnant) in and around Mekelle, Ethiopia and by way of comparison, 62 HF cows (25 non-pregnant and 37 pregnant), either managed indoors or outdoors in a commercial farm in Edinburgh, United Kingdom. The mean milk fat, protein, lactose, total solid (TS) and solid-no-fat (SNF) recorded were 2.36%, 3.46%, 4.37%, 10.39% and 7.82%, in crossbred dairy cows, compared with 5.05%, 3.71%, 4.72%, 13.68% and 8.43%, in HF cows, respectively. Significantly lower (p < 0.05) level of macronutrient was recorded in milk from crossbred cows than HF cows. Milk fat in both breeds was affected by reproductive status, farm (nutritional) management and stages of lactation, but not by parity. In both cattle breeds, the milk fat content was significantly higher (p < 0.05) in pregnant than non-pregnant cows. Milk protein content was significantly (p < 0.05) affected by reproductive status (in crossbreds) and stages of lactation (in both breeds), but not by farm management or parity. Reproductive status (in crossbreds), stages of lactation (in both breeds) and parity (in crossbreds) affected lactose level; however, farm management had no effect on lactose level in both breeds. Milk fat was the most affected macronutrient content in both breeds. Low milk fat level in crossbred cows could be as a result of samples obtained from early milking coupled with nutritional management. In conclusion, the present study has determined the major reproductive problems in crossbred dairy cattle, assessed their actual reproductive status using rapid, cost effective, simple and applicable on-farm P4 tests, and established P4 and estradiol profiles at different reproductive status. The major breeding problem was poor estrus detection evidenced when animals reported anestrus were confirmed normally cycling using on-farm as well as laboratory P4 assays. These studies offer opportunities for establishing simple field reporting of reproductive status in these crossbred dairy cattle, which can have a major impact on breeding management and productivity.

La reproduction de la vache allaitante dépend de son état nutritionnel. Les représentations existantes de cette relation se focalisent jusqu’à présent sur des variables nutritionnelles statiques et sur quelques composantes de la performance de reproduction. L’objet de cette thèse est de proposer une représentation dynamique des interrelations entre fonctions de nutrition et de reproduction afin de mieux expliquer leur fonctionnement et de simuler les enchaînements de cycles de production au cours de la carrière de la vache. Compte-tenu des contextes économique et climatique, des périodes de contraintes nutritionnelles risquent d’intervenir à n’importe quel moment du cycle de production et pourront affecter la performance de reproduction. Au vu de ce caractère aléatoire, l’approche dynamique permet d’étudier la sensibilité des composantes de la performance de reproduction à la quantité et à la dynamique des réserves lipidiques. Sur la base de concepts développés chez la vache laitière, une représentation conceptuelle des interrelations entre nutrition et reproduction a été réalisée. Cette représentation propose deux trajectoires des réserves lipidiques : à l’équilibre et en situation de contrainte nutritionnelle (trajectoire adaptative). L’écart entre ces trajectoires influence les différentes composantes de la performance de reproduction. L’acquisition et l’analyse de données expérimentales observées sur des vaches Charolaises en situation nutritionnelle non contraignante, puis contraignante a permis de quantifier ces représentations conceptuelles. Une première implémentation informatique a été réalisée, permettant de tester la sensibilité des composantes de la performance de reproduction à différentes contraintes nutritionnelles au cours de la vie productive. / Beef cattle reproduction depends on nutritional status. Until now, relations between nutrition and reproduction focused on static nutritional variables and on few components of the reproductive performance. This work aims to propose a dynamic framework of the interrelations between nutrition and reproduction to better understand it and to simulate succession of reproductive cycles. Due to economic and climatic context, nutritional constraints may occur all around the nutrition cycle whatever the physiological status. A dynamic approach allowed studying the sensitivity of reproductive performance to body lipid quantity and change. Based on a conceptual approach developed in dairy cows, a conceptual framework of the interrelations between nutrition and reproduction has been realized. This proposes two body lipid trajectories: without nutritional constraint and under nutritional constraint (adaptive trajectory). Difference between theses trajectories influences the different components of the reproductive performance. Experimental data from Charolais cows in a not constraining environment and under nutritional constraints allowed quantifying these conceptual interrelations between nutrition and reproduction. A computer model has been built to test the sensitivity of reproductive performance to varying nutritional environments.

This work deals with an analysis of breeding cattle in the agricultural cooperative Agra Březnice u Bechyně. Data on milk production and reproduction was obtained from records of performance tests and livestock records. The results of performance and reproduction in the years 2010 to 2012 shows that the monitored breeding achieved when compared to the average population of Czech Pied cattle bred in the Czech Republic, above-average values. The efficiency of milk production in the reporting period increased by an average of 394 kg. Milk composition is at the population level. The fat content was in the period, on average, 0.02% lower and the protein content was about 0.01% lower than the values of the population in the Czech Republic. The reproduction of purebred breeding is used in a closed herd turnover. The reproductive performance achieves significantly less value than the population average length of service period. The other reproductive indicators, with the exception of insemination index reached in the period better values than the average of these values achieved in the Czech Republic. The results showed that the most common reason for withdrawal from dairy herds are problems with disease of the legs and udder disease. These problems need to be addressed in the short term better approach to monitoring and prevention in the long term appears to be the most important completion of a new barn. The breeding value of bulls used in reproduction was satisfactory level.

This work shows that the level of reproduction is influenced primarily by management reproduction. Selected indicators reproductions reached cows of the Holstein breed below-average values u (service period, pregnancy after first insemination and insemination index) to average values (interim) and achieve the goals set out indicators breeding Holstein cattle in lactation. Recommendations for breeders is to improve search říjících the cows. Further improve the diagnosis of pregnancy in cows inseminated. Improve the overall management of the herd reproduction.

O objetivo desse trabalho foi avaliar a influência da uniformização de leitegadas com leitões de diferentes pesos no consumo alimentar, assim como, nas perdas corporais no período lactacional, no desempenho reprodutivo subsequente de primíparas e o desempenho de suas leitegadas até o desmame. Primíparas suínas foram separadas em 3 grupos: grupo A (n= 31) – leitegadas com 14 leitões leves (1,0-1,2 kg); grupo B (n= 32) – leitegadas com 7 leitões leves e sete leitões com peso intermediário (1,4-1,6kg); e, grupo C (n= 31) – leitegadas com 14 leitões com peso intermediário. Nas fêmeas foram realizadas as mensurações de peso corporal (24 horas após o parto e nos dias 7, 15 e 19 de lactação), espessura de toucinho (ET) e escore corporal visual (ECV) (24 horas após o parto e aos 19 dias de lactação) e consumo médio diário (CMD). Dados referentes ao subsequente intervalo-demame-estro (IDE), taxa de parto e número de leitões nascidos foram obtidos através do programa de gerenciamento da granja. Os leitões foram pesados individualmente na uniformização (dia zero) e aos 19 dias de idade. As variáveis relativas ao desempenho dos leitões foram analisadas como sendo 4 grupos (A, B1, B2 e C) onde B1 e B2 correspondem aos leitões leves e intermediários do grupo B, respectivamente. O consumo alimentar e as perdas lactacionais das fêmeas não foram influenciados pelo peso dos leitões à uniformização (P>0,10). O IDE foi maior (P=0,08) e a porcentagem de fêmeas que apresentaram estro em até sete dias após o desmame foi menor (P<0,10) no grupo C comparado ao grupo A. A taxa de parto e o tamanho da segunda leitegada foram similares entre os grupos de fêmeas (P>0,10). Os leitões do grupo B2 tiveram um maior ganho de peso diário (GPD) (P=0,07) e maior peso no dia 19 (P=0,07) que os leitões do grupo C. Em conclusão, as leitegadas compostas somente por leitões de peso intermediário prolongaram o IDE comparadas àquelas compostas apenas por leitões leves. Os leitões de peso intermediário tiveram melhor desempenho quando competiram com leitões leves do que com leitões de peso similar. / The objective of this study was to evaluate the effect of crossfostering piglets with different birth weight on feed intake, body reserve losses and reproductive performance of primiparous sows and on performance of their litters until weaning. Primiparous sows were allocated in three groups: group A (n= 31) – litters with 14 Light piglets (1.0-1.2 kg); group B (n= 32) – litters with seven Light piglets and seven Intermediate piglets (1.4-1.6 kg), and group C (n= 31) – litters with 14 Intermediate piglets. Sows were weight up to 24 h after farrowing and on days 7, 15 and 19 of lactation. Backfat thickness (BT) and body conditional score (BCS) were measured up to 24 h after farrowing and again at day 19 of lactation. Feed intake was measured daily during. Data regarding the weaning-to-estrus interval (WEI), farrowing rate and number of piglets born were obtained from a backup of the farm management program. Piglets were individually weighed at crossfostering (day zero) and day 19 of lactation. Variables concerning the performance of piglets were analyzed as four groups (A, B1, B2 and C) where B1 and B2 corresponded to Light and Intermediate piglets of group B, respectively. The average daily feed intake (ADFI) and lactation losses were not influenced by weight of piglets at crossfostering (P>0.10). Percentage of sows showing estrus until Day 7 after weaning was lower (P<0.10) and WEI was higher (P=0.08) in group C compared to group A. Farrowing rates and second litter size were similar among groups (P>0.10). Piglets of B2 group were higher daily weight gain (DWG) (P=0.07) and a higher weight at Day 19 (P=0.07) than piglets of group C. In conclusion, litters composed entirely of Intermediate piglets prolonged WEI compared to litters with Light weight piglets. Intermediate piglets perform better when competing with lighter piglets than with piglets of similar weight.

O objetivo do trabalho foi relacionar a baixa produtividade com perdas corporais lactacionais, caracterizando o perfil das fêmeas propensas ao risco, estudar detalhadamente este grupo de fêmeas e avaliar possíveis alternativas para minimizar os efeitos do catabolismo. O primeiro experimento analisou fêmeas de diferentes ordens de parto (OP) e perda de peso na lactação. Houve efeito da interação entre ordem de parto e perda de peso na taxa de parto das fêmeas (P<0,05) em fêmeas OP1 e OP2. Não houve interação da classe de OP com classe de perda de peso (P>0,05) para IDE e total de leitões nascidos. Fêmeas OP1 apresentaram IDE mais longo e menor tamanho da leitegada no parto subsequente (P<0,05) em comparação às fêmeas OP2 e OP3-5. As perdas corporais na lactação não afetaram o IDE (P>0,05), mas reduziram o tamanho da leitegada do parto seguinte (P<0,05). Os resultados sugerem que as fêmeas mais jovens são mais sensíveis ao catabolismo, afetando o desempenho reprodutivo após o desmame. Além disso, perdas corporais lactacionais reduzem o tamanho da leitegada subsequente. O segundo experimento estudou o efeito do peso ao parto (PP) e consumo energético em relação à mantença (CEM) na lactação de fêmeas OP1 e OP2 no desempenho reprodutivo. O baixo CEM afetou as perdas corporais em ambas as OP (P<0,05). O peso ao parto não afetou o consumo alimentar em fêmeas OP1, mas influenciou a ingestão de OP2. A concentração sérica de NEFA foi influenciada pelo CEM em OP1 e OP2. Alto CEM de OP1 implicou em aumento de ureia. Em OP1, o tamanho da leitegada não foi afetado pelo PP ou CEM, mas foi reduzida em OP2 com baixo PP ou CEM. O terceiro trabalho investigou o efeito de atrasar o primeiro serviço de OP1 após o desmame com tratamento com altrenogest (ALT) ou cobertura do segundo estro após o desmame (SKIP), comparado à inseminação no primeiro estro (CON). A restrição alimentar de 60% na última semana de lactação induziu uma perda média de peso corporal de 17kg. Quanto maior foi o intervalo desmame-serviço, maior foi a recuperação do peso à inseminação. O grupo ALT foi mais síncrono na entrada ao estro após a retirada do produto. A taxa de prenhez foi maior no SKIP e CON. ALT teve maior peso de corpora lutea e níveis de progesterona até 120h pós-ovulação. Não foi observada diferenças na taxa de ovulação, embriões viáveis, sobrevivência embrionária, tamanho dos embriões ou volume de fluido placentário. Dependendo do sistema de produção, estas estratégias podem trazer benefícios econômicos, quando aplicadas com critério em fêmeas com maior risco à baixa produtividade, uma vez que custo deve ser considerado. / The aim of this work was to relate low productivity to lactational weight loss, identifying the profile of females with more risk, study in details this cohort of sows and evaluate possible alternatives to minimize the effects of catabolism. The first trial evaluated females of different parity order (PO) and weight loss during lactation. There was interaction effect between parity order and weight loss on farrow rate (P<0.05) in PO1 and PO2 females. There was no interaction between PO and weight loss class (P>0.05) on WEI and subsequent total born. PO1 females presented longer WEI and lower litter size on subsequent farrowing compared to PO2 and PO3-5 females. Weight loss did not affect WEI (P>0.05), but it was related to a decrease of litter size in the subsequent farrowing (P<0.05). Results suggest young females are more sensitive to catabolism, affecting reproductive performance post weaning. The second experiment studied the effect of body weight at farrowing (BWF) and energy intake related to maintenance (MEIM) during lactation on subsequent reproductive performance of PO1 and PO2 sows. Low MEIM affected body weight loss in both PO (P<0.05). BWF did not affect energy intake in PO1 sows but influenced the consumption in PO2 sows. Serum NEFA concentration was influenced by MEIM in PO1 and PO2 sows. High MEIM PO1 sows showed higher urea concentration. In PO1, litter size was not affected by BWF or MEIM but was reduced in PO2 with Low BWF or MEIM. Third trial investigated the effect of delayed breeding in weaned PO1 sows with altrenogest treatment (ALT) or breeding at second estrus after weaning (SKIP), compared to breeding at first estrus after weaning (CON). Feed restriction at 60% during last week of lactation induced 17kg of body weight loss. The longer weaning to service interval resulted in greater recover of body weight at breeding. ALT group was more synchronized in estrus after altrenogest withdrawal. Pregnancy rate was greater in SKIP and CON. ALT had higher corpora lutea weight and progesterone levels at 120h post-ovulation. No differences in ovulation rate, live embryos, embryo survival, embryo size, or placental fluid volume were detected. Depending on the production system, these strategies may offer economic benefits, when carefully applied in a cohort of females with more risk to low productivity, since costs must be considered.

As leitoas são consideradas a categoria de matrizes que deve ter uma atenção especial na preparação para a vida produtiva, pois a introdução no momento certo no rebanho de produção é crucial para o desempenho e longevidade desta futura matriz. Todo período experimental deste trabalho foi realizado em uma granja produtora de leitões, localizada no Centro-Oeste do país, com capacidade de alojar 2400 fêmeas (Camborough 22®). O primeiro estudo teve como objetivo determinar se leitoas com maiores taxas de crescimento, em diferentes categorias de idade no início do estímulo à puberdade, apresentam o primeiro estro em idade mais precoce. As leitoas foram avaliadas de acordo com dois grupos de idade à exposição ao cachaço (A= 130-149 d, n= 751 e B= 150-170 d, n= 735) e de acordo com três classes de taxa de crescimento (TC) do nascimento ao início do estímulo (I = 550-649 g/d, n= 371; II= 650-725 g/d, n= 749 e III= 726- 830 g/d, n= 366). A idade no momento da exposição ao cachaço para as leitoas dos Grupos A e B foram 142,6 ± 4,9 e 157,0 ± 5,1 dias, respectivamente. No geral, em 40 dias de estimulação, 85% das leitoas foram púberes. No grupo A, leitoas da classe TCIII manifestaram maior percentual cumulativo de fêmeas em estro dentro de 10 dias (38,1 vs. 29,0 vs. 27,6%) e 20 dias de estimulação (59,7 vs. 48,7 vs. 48,2%) em comparação às classes TCII e TCI, respectivamente (P<0,05). No entanto, dentro do grupo B não houve diferença nos percentuais de fêmeas púberes entre as classes de taxa de crescimento TCIII, TCII e TCI, aos 10 dias (43,2% vs. 45,3% vs. 44,3%) e 20 dias (63,8% vs. 67,3% vs. 63,7%) após a exposição ao macho. Leitoas da classe TCIII estimuladas mais jovens (grupo A) foram mais precoces à puberdade (P<0,05) do que as de baixa taxa de crescimento (159,6 vs 164,8 dias). No entanto, a idade à puberdade não foi afetada pela taxa de crescimento, quando as leitoas foram expostas ao cachaço em idade mais avançada (grupo B). No geral, a idade à puberdade foi positivamente associada com a idade no início da exposição ao cachaço (r=0,38; P<0.0001), e o intervalo de estímulo foi menor (r= -0,19; P<0.0001) em leitoas estimuladas mais velhas. Em conclusão, a estimulação da puberdade pode ser efetuada pela exposição ao macho em idade menos avançada em leitoas com alta taxa de crescimento. O segundo estudo foi desenvolvido com o objetivo de avaliar o reflexo da taxa de crescimento e da espessura de toucinho (ET) na 1ª inseminação, sobre o desempenho subsequente da leitoa e sobre a variação de peso da leitegada ao nascimento. As leitoas foram separadas em três classes de TC do nascimento até a primeira inseminação: TCI (600-700 g/d; n= 345), TCII (701-770 g/d; n= 710) e TCIII (771-870 g/d; n= 366). As análises também foram realizadas considerando três grupos de leitoas de acordo com a ET (mm) na inseminação: ET 10-15 (n= 405), ET 16-17 (n= 649) e ET 18-23 (n= 367). Não houve diferença nas taxas de parto e retorno ao estro entre os grupos de TC e ET (P>0,05). Leitoas TCII e TCIII tiveram, respectivamente, 0,5 e 0,9 leitões a mais quando comparadas às leitoas TCI (P<0,05). Porém, leitoas TCIII apresentaram maior percentual de natimortos intra-parto (P<0,05) em comparação às leitoas das classes TCI e TCII. Leitoas da classe TCIII apresentaram maior número de leitões (P<0,05) pesando abaixo de 1.200 g ao nascimento, comparativamente às leitoas TCI. Além disso, o coeficiente de variação do peso ao nascer foi menor nas fêmeas TCI comparativamente ao das fêmeas TCII e TCIII. Leitoas TCIII apresentaram maior percentual de leitegadas com coeficiente de variação acima de 20%, comparativamente às TCI e TCII (P<0,05). Maiores números de leitões nascidos e nascidos vivos foram observados nas fêmeas do grupo ET16-17 em comparação ao grupo ET10-15 (P<0,05). Não houve diferença entre os grupos de ET no número de natimortos e nem nas variáveis relativas ao peso ao nascer dos leitões (P>0,05). Esses resultados mostram que não há vantagem, em termos de taxa de parto e número de leitões nascidos vivos, em realizar a primeira cobertura de leitoas com ganho de peso acima de 770 g/d e com mais de 17mm de ET. O terceiro estudo teve por objetivo avaliar a influência do peso da primeira inseminação sobre o desempenho reprodutivo e sobre a taxa de descarte ao longo dos três primeiros partos. As leitoas foram classificadas em três grupos, de acordo com seu peso na primeira inseminação: GI (130-150 kg, n= 298), GII (151-170 kg, n= 1007) e GIII (171-200 kg, n= 421). Leitoas do grupo GIII tiverem maior número total de leitões nascidos e maior número de natimortos (P<0,05) no primeiro parto comparativamente aos demais grupos de peso. No entanto, o número total de leitões nascidos em três partos não diferiu entre os grupos (P>0,05). Na inseminação após o primeiro desmame, houve diferença (P<0,05) na taxa de parto entre os três grupos de peso (89,3% vs. 80,3% vs. 74,9%) e a taxa de retorno ao estro foi menor no grupo GI (9,4%) do que nos grupos GII (16,4%) e GIII (19,5%). Ao final dos três partos, houve uma taxa de retenção de 66,6%. As taxas de descarte devido a problemas locomotores e por falha reprodutiva foram, respectivamente 10,8% e 11,2%. A taxa de remoção do grupo GIII (38,9%) foi maior (P= 0,006) do que no grupo GII (31,5%) e tendeu a ser maior (P= 0,06) do que no grupo GI (32,2%). A taxa de descarte devido a problemas locomotores foi superior (P<0,05) em fêmeas com maior peso na primeira inseminação (GIII) comparativamente com as dos grupos GII e GI (15,2% vs. 10,3% vs. 6,0%). Considerando que fêmeas mais pesadas apresentam maior taxa de descarte por problemas locomotores e menor taxa de retenção sem nenhuma falha reprodutiva, ao longo de três ciclos de produção, não é vantajoso realizar o primeiro acasalamento de leitoas com mais de 150 kg de peso corporal. / Gilts are regarded as the class of females that must have special attention in preparation for productive life, because the introduction at the right time in the herd of production is crucial for the future performance and longevity of this female. The studies were performed in a sow farm with capacity to accommodate 2,400 sows (Camborough 22®), located in the Midwest of Brazil (Parallel 14º). The objective of the first study was to verify whether pubertal estrus could be influenced by the growth rate and age of gilts at the onset of boar exposure. Gilts were evaluated according to two groups of age at boar exposure (A= 130-149 d, n= 751 and B= 150- 170 d, n= 735) and three classes of growth rate (Low= 550-649 g/d, n= 371; Intermediate= 650- 725 g/d, n= 749 and High= 726-830 g/d, n= 366). Gilts of groups A and B were, respectively, 142.6 ± 4.9 and 157.0 ± 5.1 days of age at the onset of boar exposure. Overall, 85% of gilts showed estrus within 40 days of boar exposure. Within group A gilts a higher (P<0.05) cumulative percentage of estrus within 10 days (38.1 vs. 29.0 vs. 27.6%) and 20 days (59.7% vs. 48.7% vs. 48.2%) of stimulation was observed in High than in Intermediate and Low growth rate gilts. Nevertheless, within group B there was no difference (P<0.05) in the percentage of estrus among High, Intermediate and Low growth rate classes within 10 days (43.2% vs. 45.3% vs. 44.3%) and 20 days (63.8% vs. 67.3% vs. 63.7%) of boar stimulation. Within group A, puberty was attained earlier (P<0.05) in High than in Low growth rate gilts (159.6 vs. 164.8 days). However, age at puberty was not affected by growth rate, when gilts were exposed to boar at an older age (group B). Overall, age at puberty was positively associated with the age at the onset of boar exposure (r= 0.38; P<0.0001) and the older the gilts were at boar exposure the lower was the interval (r= -0.19; P<0.0001) from stimulation to onset of puberty. In conclusion, successful stimulation of puberty can be obtained through an earlier exposure to boars in high growth rate gilts. The second study evaluated the influence of growth rate (GR) and backfat thickness (BF), at first mating of gilts, on the reproductive performance until the first farrowing and on the variation in birth weight of piglets. Gilts were categorized into three groups according to GR from birth until first mating: GRI (600-700 g/d, n= 345), GRII (701-770 g/d, n= 710) and GRIII (771-870 g/d, n= 366). Analyses were also performed considering three groups formed according to BF (mm) at mating: BF10-15 (n= 405); BF16-17 (n= 649) and BF18-23 (n= 367). There were no differences in farrowing rate and return to estrus rate among BF or GR groups (P>0.05). GRII and GRIII females had larger litter size compared to GRI gilts (P<0.05), respectively 0.5 and 0.9 more piglets, but a higher percentage of intrapartum stillborns (P<0.05) was observed in GRIII than in GRI and GRII females. Moreover GRIII females had more piglets (P<0.05) weighing less than 1,200 g, litters with a higher coefficient of variation for birth weight and a higher percentage of litters with coefficient of variation above 20% (P<0.05) than GRI females. More total born and born alive piglets were observed in BF16-17 compared with BF10-15 females (P<0.05).There were no differences among BF groups in number of stillborn neither in variables concerning the birth weight of piglets (P>0.05). These results show that there is no advantage, in terms of farrowing rate and number of born alive, in performing the first mating of gilts with GR >770g/d and BF >17 mm. The objective of the third study was to evaluate the influence of the weight at the first mating of gilts on the reproductive performance and on the removal rate until the third farrowing. Gilts were categorized into three groups according to weight at first mating: GI (130- 150 kg, n= 298), GII (151-170 kg, n= 1007) and GIII (171-200 kg, n= 421). In the first farrowing, GIII females had larger litter size compared to GRI and GII gilts (P<0.05), but a higher percentage of stillborns (P<0.05) also was observed in GRIII than in GRI and GRII females. However, total born over three parities were not different among groups (P>0.05). In the insemination after the first weaning, there were differences (P<0.05) in farrowing rate among all weight groups (89.3% vs. 80.3% vs. 74.9%) and return to estrus rate was lower in GI (9.4%) than in GII (16.4%) and GIII (19.5%) groups. The overall retention rate over three parities was 66.6%. Culling rate due to locomotion problems was 10.8% and due to reproductive failure was 11.2%.The removal rate over three parities in GIII females (38.9%) was higher (P= 0.006) than in GII females (31.5%) and tended to be higher (P= 0.06) than in GI females (32.2%). The culling rate due to locomotors problems was different (P<0.05) among all groups (6.0% vs. 10.3% vs. 15.2% for GI, GII and GIII, respectively). Taking into account that heavy females have higher culling rates due to locomotors disorders and lower retention rate without reproductive failure, over three productive cycles, it is not advantageous to perform the first mating of gilts with more than 150 kg of body weight.

LIMA, Rômulo Messias Diógenes. Desempenho reprodutivo de ovelhas morada nova submetidas a indução do estro pelo efeito macho. 2013. 61 f. : Dissertação (Mestrado) - Universidade Federal do Ceará, Centro de Ciências, Departamento de Zootecnia, Programa de Pós-Graduação em Zootecnia. Fortaleza-CE, 2013. / Submitted by Eric Santiago (erichhcl@gmail.com) on 2016-08-10T14:18:25Z No. of bitstreams: 1 2013_dis_rmdlima.pdf: 1214970 bytes, checksum: 91de88bef1fe19d8086d5a1018e5fce7 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-10T15:17:34Z (GMT) No. of bitstreams: 1 2013_dis_rmdlima.pdf: 1214970 bytes, checksum: 91de88bef1fe19d8086d5a1018e5fce7 (MD5) / Made available in DSpace on 2016-08-10T15:17:34Z (GMT). No. of bitstreams: 1 2013_dis_rmdlima.pdf: 1214970 bytes, checksum: 91de88bef1fe19d8086d5a1018e5fce7 (MD5) Previous issue date: 2013 / This study aimed to evaluate the efficiency of the male as the inductive effect of estrous activity in three categories (Nulliparous, Primiparous and Pluriparous) of crossbred ewes (MORADA NOVA X SPRD), and reproductive performance, from data obtained from manifestação estrus; intervalo between the introduction of the male and the onset of estrus; synchronization degree; repetition estrus; pregnancy rate; birth rate; twinning rate and prolificacy index. In two consecutive years were used, 81 animals, 02 male sheep (vasectomised a thug and a breeder) and 79 ewes divided into three categories, Nulliparous (Nul), Primiparous (Pri) and Pluriparous (Plu). During the first year, the females were subjected to the male effect method (EM), and the following year to the traditional method (MT), both with the breeding season of 42 days duration. Significant difference (P <0.05) was noted for the degree of synchronization of the EM with females (25.42%) compared to females with MT (10.17%). Females Nul and Pri subjected to male effect [30% (Nul), 42.10% (Pri)] were more responsive to the degree of synchronization, to the detriment of their counterparts in the traditional method [10% (Nul); 10.52 % (Pri)]. When specified for each category of females was noted superiority in results (P <0.05) within the same method for MT index prolificacy and twinning rate of females Plu (prolificacy: 2.25; twins: 95%) compared to Nul (prolificacy: 1.16; twinning: 15.79%) and Pri (prolificacy: 1.33; twinning: 33.33%). Also in the same method there was a significant difference (P <0.05) for the EM method. However, being greater for females Plu (prolificacy: 2.22; twinning: 88.88%) and Pri (prolificacy: 1.94; twinning: 72.22%) over the Nul (prolificacy: 1.39; twinning: 38.89%). Among the methods, EM Primiparous females (72.22%) were higher (P <0.05) females MT (33.33%) regarding twinning rate. As a conclusion it can be stated that the effect male appears feasible for synchronization of estrus in females up to first order of birth. Besides possibly cause better ovulation rate due to better results for twinning rate and prolificacy index. / O presente trabalho teve como objetivo principal avaliar a eficiência do efeito macho como método indutivo da atividade estral em três categorias (Nulíparas, Primíparas e Pluríparas) de fêmeas ovinas mestiças (MORADA NOVA X SPRD), e no desempenho reprodutivo, a partir de dados obtidos de manifestação de estro; intervalo entre a introdução do macho e o início do estro; grau de sincronização; repetição de estros; taxa de prenhez; taxa de partos; taxa de gemelaridade e índice de prolificidade. Em dois anos consecutivos foram utilizados, 81 animais, sendo 02 machos ovinos (um rufião vasectomizado e um reprodutor) e 79 ovelhas distribuídas em três categorias, Nulíparas (Nul), Primíparas (Pri) e Pluríparas (Plu). No primeiro ano, as fêmeas foram submetidas ao método efeito macho (EM), e no ano seguinte ao método tradicional (MT), ambos com estação de monta de 42 dias de duração. Diferença significativa (P<0,05) foi notada para o grau de sincronização das fêmeas EM com (25,42%) em relação às fêmeas MT com (10,17%). As fêmeas Nul e Pri submetidas ao efeito macho [30% (Nul); 42,10% (Pri)] foram mais responsivas ao grau de sincronização, em detrimento a suas correspondentes no método tradicional [10% (Nul); 10,52% (Pri)]. Quando especificada por categoria de fêmeas, notou-se superioridade nos resultados (P<0,05) dentro do mesmo método MT para índice de prolificidade e taxa de gemelaridade das fêmeas Plu (prolificidade: 2,25; gemelaridade: 95%) em relação às Nul (prolificidade: 1,16; gemelaridade: 15,79%) e Pri (prolificidade: 1,33; gemelaridade: 33,33%). Também dentro do mesmo método houve diferença significativa (P<0,05) para o método EM. Porém, com superioridade das fêmeas Plu (prolificidade: 2,22; gemelaridade: 88,88%) e Pri (prolificidade: 1,94; gemelaridade: 72,22%) em detrimento as Nul (prolificidade: 1,39; gemelaridade: 38,89%). Entre os métodos, as fêmeas Primíparas EM (72,22%) foram superiores (P<0,05) as fêmeas MT (33,33%) no tocante a taxa de gemelaridade. Como conclusão pode-se afirmar que o efeito macho se apresenta viável para a sincronização do estro em fêmeas de até primeira ordem de parto. Além de possivelmente provocar melhor taxa de ovulação, em decorrência de melhores resultados de taxa de gemelaridade e índice de prolificidade.