O objetivo deste estudo foi verificar a associação do desenvolvimento de peso corporal da 1º inseminação até o 1º desmame com o desempenho reprodutivo, produção de leitões e taxa de descartes até o 3º parto, em 196 primíparas Landrace x Large White, usando modelos de regressão logística. O peso corporal (PC) foi medido na inseminação artificial (IA), 24h após o 1º parto e no dia do desmame. Na 1º IA, primeiro parto e desmame o PC foram em média 140.4 kg, 170.8 kg e 163.7 kg, respectivamente. O intervalo desmame-estro (IDE), o número de leitões nascidos totais no primeiro, segundo e após três partos, e a taxa de descarte até terceiro parto foram, em média 5.7 dias, 12.5, 11.8 e 36.7 leitões nascidos, e 10.2%, respectivamente. O aumento de 10 kg no ganho de peso na primeira prenhes (OR = 0.63), no peso ao 1º parto (OR = 0.63), peso ao 1º desmame (OR = 0.69) e ganho de peso entre a 1º IA e o 1º desmame (OR = 0,67) diminuiu a percentagem de primíparas com longo IDE. Os aumentos da duração da lactação e do número de leitões desmamados foram responsáveis pela, respectivamente, diminuição (OR = 0.79 por dia de lactação) e aumento (OR = 1.45 por leitão desmamado) do percentual de fêmeas com IDE longo. Primíparas com PC <159.5 kg a desmama apresentaram maior taxa de não-parto (TNP) em comparação com porcas com PC >170 kg (OR = 4.73). Porcas com <17.5 kg de ganho entre a 1º IA e o 1º desmame tiveram maior chance (OR = 4,88) de TNP do que fêmeas > 30 kg. Cada dia adicional de lactação diminuiu a TNP (OR = 0.77). As fêmeas com PC <139 kg na 1º IA apresentaram maior porcentagem de leitegadas pequenas no segundo parto (NT2P, OR = 2.00) e após três parições (OR = 3.28) em comparação com aquelas pesando ≥139 kg. Porcas com ganho de peso <25 kg durante a primeira prenhes apresentaram maior chance de NT2P (OR = 3.01), em comparação com porcas ganhando acima de 35 kg. A cada 10 kg de aumento no peso ao primeiro desmame e no ganho de peso entre a 1º IA e o 1º desmame (OR = 0.71 e 0.73, respectivamente) diminuiu a taxa de descarte total, e por razões reprodutivas (OR = 0.57 e 0.61, respectivamente). A taxa de descarte até o 3º parto aumentou em porcas com menores leitegadas a primeira parição. Os resultados mostram que atingir um peso mínimo à 1º IA é importante, mas também deve ser considerado o ganho de peso corporal adequado até o primeiro desmame para melhor desempenho reprodutivo, produtividade, e retenção de matrizes no rebanho. / The aim of this study was to verify the association of sow body weight development until 1st weaning with the reproductive performance, piglet production and culling rate until 3rd farrowing in 196 Landrace x Large White primiparous sows using logistic regression models. Body weight (BW) was measured at artificial insemination (AI), 24h after farrowing and on the weaning day. At 1st AI, 1st farrowing and 1st weaning the BW was on average 140.4 kg, 170.8 kg and 163.7 kg, respectively. The weaning-to-estrus interval (WEI), the number of piglets born at 1st, 2nd and over three parities, and culling rate until 3rd farrowing were on average 5.7 days, 12.5, 11.8 and 36.7 piglets born, and 10.2%, respectively. Each 10kg increase in weight gain in 1st pregnancy (OR= 0.63), weight at 1st farrowing (OR= 0.63), weight at 1st weaning (OR= 0.69) or weight gain from 1st AI to 1st weaning (OR= 0.67) decreased the percentage of primiparous sows with long WEI. Increasing lactation length and increasing the number of weaned piglets were responsible for respectively decreasing (OR=0.79 per day of lactation) and increasing (OR= 1.45 per piglet weaned) the percentage of sows with long WEI. Sows with <159.5 kg at weaning had higher non-farrowing rate (NFR) compared to sows with >170 kg (OR = 4.73). Sows with <17.5 kg of gain from 1st AI to 1st weaning had higher odds (OR= 4.88) of NFR than sows gaining >30 kg. Each additional lactation day decreased the NFR (OR = 0.77). Females weighing < 139 kg at 1st AI had higher percentages of small number of total born in second parity (STB2, OR= 2.00) and over three parities (OR = 3.28) compared to those weighing ≥139 kg. Sows with weight gain at 1st pregnancy <25 kg had higher odds of STB2 (OR= 3.01) compared to sows gaining >35 kg. Each 10 kg of increase in weight at 1st weaning or in weight gain from 1st AI to 1st weaning decreased the total culling rate (OR= 0.71 and 0.73, respectively) and culling by reproductive reasons (OR= 0.57 and 0.61, respectively). Culling rate until 3rd farrowing was also increased in sows with smaller first litter size. The results show that not only to reach a minimum weight at 1st AI but also to have an adequate body weight gain until 1st weaning is important for the reproductive performance, productivity and retention of sows in the herd.

O objetivo deste estudo foi verificar a associação do desenvolvimento de peso corporal da 1º inseminação até o 1º desmame com o desempenho reprodutivo, produção de leitões e taxa de descartes até o 3º parto, em 196 primíparas Landrace x Large White, usando modelos de regressão logística. O peso corporal (PC) foi medido na inseminação artificial (IA), 24h após o 1º parto e no dia do desmame. Na 1º IA, primeiro parto e desmame o PC foram em média 140.4 kg, 170.8 kg e 163.7 kg, respectivamente. O intervalo desmame-estro (IDE), o número de leitões nascidos totais no primeiro, segundo e após três partos, e a taxa de descarte até terceiro parto foram, em média 5.7 dias, 12.5, 11.8 e 36.7 leitões nascidos, e 10.2%, respectivamente. O aumento de 10 kg no ganho de peso na primeira prenhes (OR = 0.63), no peso ao 1º parto (OR = 0.63), peso ao 1º desmame (OR = 0.69) e ganho de peso entre a 1º IA e o 1º desmame (OR = 0,67) diminuiu a percentagem de primíparas com longo IDE. Os aumentos da duração da lactação e do número de leitões desmamados foram responsáveis pela, respectivamente, diminuição (OR = 0.79 por dia de lactação) e aumento (OR = 1.45 por leitão desmamado) do percentual de fêmeas com IDE longo. Primíparas com PC <159.5 kg a desmama apresentaram maior taxa de não-parto (TNP) em comparação com porcas com PC >170 kg (OR = 4.73). Porcas com <17.5 kg de ganho entre a 1º IA e o 1º desmame tiveram maior chance (OR = 4,88) de TNP do que fêmeas > 30 kg. Cada dia adicional de lactação diminuiu a TNP (OR = 0.77). As fêmeas com PC <139 kg na 1º IA apresentaram maior porcentagem de leitegadas pequenas no segundo parto (NT2P, OR = 2.00) e após três parições (OR = 3.28) em comparação com aquelas pesando ≥139 kg. Porcas com ganho de peso <25 kg durante a primeira prenhes apresentaram maior chance de NT2P (OR = 3.01), em comparação com porcas ganhando acima de 35 kg. A cada 10 kg de aumento no peso ao primeiro desmame e no ganho de peso entre a 1º IA e o 1º desmame (OR = 0.71 e 0.73, respectivamente) diminuiu a taxa de descarte total, e por razões reprodutivas (OR = 0.57 e 0.61, respectivamente). A taxa de descarte até o 3º parto aumentou em porcas com menores leitegadas a primeira parição. Os resultados mostram que atingir um peso mínimo à 1º IA é importante, mas também deve ser considerado o ganho de peso corporal adequado até o primeiro desmame para melhor desempenho reprodutivo, produtividade, e retenção de matrizes no rebanho. / The aim of this study was to verify the association of sow body weight development until 1st weaning with the reproductive performance, piglet production and culling rate until 3rd farrowing in 196 Landrace x Large White primiparous sows using logistic regression models. Body weight (BW) was measured at artificial insemination (AI), 24h after farrowing and on the weaning day. At 1st AI, 1st farrowing and 1st weaning the BW was on average 140.4 kg, 170.8 kg and 163.7 kg, respectively. The weaning-to-estrus interval (WEI), the number of piglets born at 1st, 2nd and over three parities, and culling rate until 3rd farrowing were on average 5.7 days, 12.5, 11.8 and 36.7 piglets born, and 10.2%, respectively. Each 10kg increase in weight gain in 1st pregnancy (OR= 0.63), weight at 1st farrowing (OR= 0.63), weight at 1st weaning (OR= 0.69) or weight gain from 1st AI to 1st weaning (OR= 0.67) decreased the percentage of primiparous sows with long WEI. Increasing lactation length and increasing the number of weaned piglets were responsible for respectively decreasing (OR=0.79 per day of lactation) and increasing (OR= 1.45 per piglet weaned) the percentage of sows with long WEI. Sows with <159.5 kg at weaning had higher non-farrowing rate (NFR) compared to sows with >170 kg (OR = 4.73). Sows with <17.5 kg of gain from 1st AI to 1st weaning had higher odds (OR= 4.88) of NFR than sows gaining >30 kg. Each additional lactation day decreased the NFR (OR = 0.77). Females weighing < 139 kg at 1st AI had higher percentages of small number of total born in second parity (STB2, OR= 2.00) and over three parities (OR = 3.28) compared to those weighing ≥139 kg. Sows with weight gain at 1st pregnancy <25 kg had higher odds of STB2 (OR= 3.01) compared to sows gaining >35 kg. Each 10 kg of increase in weight at 1st weaning or in weight gain from 1st AI to 1st weaning decreased the total culling rate (OR= 0.71 and 0.73, respectively) and culling by reproductive reasons (OR= 0.57 and 0.61, respectively). Culling rate until 3rd farrowing was also increased in sows with smaller first litter size. The results show that not only to reach a minimum weight at 1st AI but also to have an adequate body weight gain until 1st weaning is important for the reproductive performance, productivity and retention of sows in the herd.

O objetivo deste estudo foi verificar a associação do desenvolvimento de peso corporal da 1º inseminação até o 1º desmame com o desempenho reprodutivo, produção de leitões e taxa de descartes até o 3º parto, em 196 primíparas Landrace x Large White, usando modelos de regressão logística. O peso corporal (PC) foi medido na inseminação artificial (IA), 24h após o 1º parto e no dia do desmame. Na 1º IA, primeiro parto e desmame o PC foram em média 140.4 kg, 170.8 kg e 163.7 kg, respectivamente. O intervalo desmame-estro (IDE), o número de leitões nascidos totais no primeiro, segundo e após três partos, e a taxa de descarte até terceiro parto foram, em média 5.7 dias, 12.5, 11.8 e 36.7 leitões nascidos, e 10.2%, respectivamente. O aumento de 10 kg no ganho de peso na primeira prenhes (OR = 0.63), no peso ao 1º parto (OR = 0.63), peso ao 1º desmame (OR = 0.69) e ganho de peso entre a 1º IA e o 1º desmame (OR = 0,67) diminuiu a percentagem de primíparas com longo IDE. Os aumentos da duração da lactação e do número de leitões desmamados foram responsáveis pela, respectivamente, diminuição (OR = 0.79 por dia de lactação) e aumento (OR = 1.45 por leitão desmamado) do percentual de fêmeas com IDE longo. Primíparas com PC <159.5 kg a desmama apresentaram maior taxa de não-parto (TNP) em comparação com porcas com PC >170 kg (OR = 4.73). Porcas com <17.5 kg de ganho entre a 1º IA e o 1º desmame tiveram maior chance (OR = 4,88) de TNP do que fêmeas > 30 kg. Cada dia adicional de lactação diminuiu a TNP (OR = 0.77). As fêmeas com PC <139 kg na 1º IA apresentaram maior porcentagem de leitegadas pequenas no segundo parto (NT2P, OR = 2.00) e após três parições (OR = 3.28) em comparação com aquelas pesando ≥139 kg. Porcas com ganho de peso <25 kg durante a primeira prenhes apresentaram maior chance de NT2P (OR = 3.01), em comparação com porcas ganhando acima de 35 kg. A cada 10 kg de aumento no peso ao primeiro desmame e no ganho de peso entre a 1º IA e o 1º desmame (OR = 0.71 e 0.73, respectivamente) diminuiu a taxa de descarte total, e por razões reprodutivas (OR = 0.57 e 0.61, respectivamente). A taxa de descarte até o 3º parto aumentou em porcas com menores leitegadas a primeira parição. Os resultados mostram que atingir um peso mínimo à 1º IA é importante, mas também deve ser considerado o ganho de peso corporal adequado até o primeiro desmame para melhor desempenho reprodutivo, produtividade, e retenção de matrizes no rebanho. / The aim of this study was to verify the association of sow body weight development until 1st weaning with the reproductive performance, piglet production and culling rate until 3rd farrowing in 196 Landrace x Large White primiparous sows using logistic regression models. Body weight (BW) was measured at artificial insemination (AI), 24h after farrowing and on the weaning day. At 1st AI, 1st farrowing and 1st weaning the BW was on average 140.4 kg, 170.8 kg and 163.7 kg, respectively. The weaning-to-estrus interval (WEI), the number of piglets born at 1st, 2nd and over three parities, and culling rate until 3rd farrowing were on average 5.7 days, 12.5, 11.8 and 36.7 piglets born, and 10.2%, respectively. Each 10kg increase in weight gain in 1st pregnancy (OR= 0.63), weight at 1st farrowing (OR= 0.63), weight at 1st weaning (OR= 0.69) or weight gain from 1st AI to 1st weaning (OR= 0.67) decreased the percentage of primiparous sows with long WEI. Increasing lactation length and increasing the number of weaned piglets were responsible for respectively decreasing (OR=0.79 per day of lactation) and increasing (OR= 1.45 per piglet weaned) the percentage of sows with long WEI. Sows with <159.5 kg at weaning had higher non-farrowing rate (NFR) compared to sows with >170 kg (OR = 4.73). Sows with <17.5 kg of gain from 1st AI to 1st weaning had higher odds (OR= 4.88) of NFR than sows gaining >30 kg. Each additional lactation day decreased the NFR (OR = 0.77). Females weighing < 139 kg at 1st AI had higher percentages of small number of total born in second parity (STB2, OR= 2.00) and over three parities (OR = 3.28) compared to those weighing ≥139 kg. Sows with weight gain at 1st pregnancy <25 kg had higher odds of STB2 (OR= 3.01) compared to sows gaining >35 kg. Each 10 kg of increase in weight at 1st weaning or in weight gain from 1st AI to 1st weaning decreased the total culling rate (OR= 0.71 and 0.73, respectively) and culling by reproductive reasons (OR= 0.57 and 0.61, respectively). Culling rate until 3rd farrowing was also increased in sows with smaller first litter size. The results show that not only to reach a minimum weight at 1st AI but also to have an adequate body weight gain until 1st weaning is important for the reproductive performance, productivity and retention of sows in the herd.

Made available in DSpace on 2014-08-20T14:37:48Z (GMT). No. of bitstreams: 1 Dissertacao_daniel_savio.pdf: 201214 bytes, checksum: f8921438dab6324aed14b7b44d06de38 (MD5) Previous issue date: 2011-12-15 / The use of artificial insemination (AI) with heterospermic doses (Het) in swine may benefit reproductive performance by diluting individual differences among boars. However, such practice may also mask the true reproductive potential of some individuals, which can be measured through homospermic AI (Hom). This study evaluated boar reproductive performance after AI with Hom and Het doses. Ejaculates were collected from 4 boars and combined in 10 treatments: 4 with Hom doses (boars A, B, C and D) and 6 with Het doses (AB, AC, AD, BC, BD and CD) all having concentration of 3 billion spermatozoa in 80 mL doses with equal contribution of each boar. The in vitro analyses of sperm quality were: sperm membrane, DNA and acrossome integrity; mitochondrial functionality; and in vitro oocyte penetration. Thereafter, 511 females having parities from 1 to 6 were inseminated and the farrowing rate (FR) and total litter size (TB) were recorded. Both FR (Hom = 90.5% and Hem = 89.9%), and TB (Hom = 12.4 ± 0.4 and Het = 12.7 ± 0.7) did not differ (P>0,05). Some differences were observed among treatments, such as: the maximum FR (98.0%) for treatment AC and the minimum (87.0) for boar B; and a difference of two piglets among the maximum (for the CD treatment) and the minimum observed value (for the AC treatment). The only difference observed on the in vitro evaluations (P<0.05), occurred for the in vitro oocyte penetration by sperm from boars B (56.4%) and C (29.0%). No differences were detected in reproductive performance after AI using homospermic and heterospemic doses. / A utilização de inseminação artificial (IA) com doses heterospérmicas (Het) pode ser benéfica para a suinocultura, por diluir deficiências individuais entre o desempenho reprodutivo de machos. No entanto, esta prática pode mascarar o potencial reprodutivo de outros reprodutores, o que poderia ser avaliado com o uso de inseminação artificial com doses homospérmicas (Hom). Este trabalho avaliou o desempenho reprodutivo de machos suínos após IA com doses Hom e Het. Ejaculados colhidos de 4 machos foram combinados em 10 tratamentos: 4 com doses Hom (machos A, B, C e D) e 6 com doses Het (AB, AC, AD, BC, BD, e CD), todos com concentração de 3 bilhões de espermatozóides em doses de 80 mL, com contribuição igual de cada macho. Realizaram-se testes para analise de integridade da membrana, do DNA espermático e do acrossoma, da funcionalidade da mitocôndria e da penetração ovocitária in vitro. Foram inseminadas 511 fêmeas de ordem de parto de 1 a 6. A taxa de parição (TP) e o número total de leitões nascidos por parto (TN) foram registrados. Tanto a TP (Hom = 90,5% e Het = 89,9%), quanto o TN (Hom = 12,4 ± 0,4 e Het = 12,7 ± 0,7), não diferiram (P>0,05). Foram observadas algumas diferenças entre os tratamentos, como a TP máxima ocorrendo para o tratamento AC (98.0%) e uma TP mínima de 87.0% para o macho B (P<0.05). Quanto ao TN, uma diferença de 2,0 leitões foi observada entre o valor máximo (tratamento CD) e o mínimo (tratamento AC). Quanto às avaliações in vitro, foram observadas diferenças apenas quanto ao teste de penetração in vitro (P<0,05), entre os machos B (56,4%) e C (29,2%). Não foram detectadas diferenças no desempenho reprodutivo com IA com doses homo e heterospérmicas.

Made available in DSpace on 2014-08-20T13:32:51Z (GMT). No. of bitstreams: 1 dissertacao_carolina_goncalves_serret.pdf: 168487 bytes, checksum: 39c57bfb4f44c9b01a747705b7e0e4a1 (MD5) Previous issue date: 2005-03-31 / Artificial insemination (AI) is a technique intensively used in the swine farms nowadays, due to its benefits related to genetic improvement and health status, allowing the industry to market high-quality healthy products. The post-cervical AI (PCAI) allows the deposition of semen in the uterine body, using 1 x 10 9 spermatozoa dose. Thus, with PCAI the fertility of one particular boar can influence the reproductive performance of a much higher number of females than in ICAI-based systems. The objective of this study was to compare the subsequent reproductive performance of swine breeding females submitted to either intra-cervical artificial insemination (ICAI) with sperm concentrations of 3.5 x 10 9 spermatozoa per dose or post-cervical artificial insemination (PCAI) with 2, 1, or 0.5 x 10 9 spermatozoa per dose. The study was conducted in a commercial farm including 338 F1 females. Among them, 232 were first inseminated 12 h after estrus detection, receiving the subsequent doses after 12 h intervals, whereas 106 were inseminated right after ovulation diagnosis through real-time ultrasound. Conception and farrowing (FR) rates for ICAI (98.9% e 97.9%, respectively) did not differ (P < 0,001) from those observed for PCAI (87.1% e 84.3%, respectively). Total litter size did not differ across treatments (P = 0.09). Although TP did not differ (P = 0,40) for different parities, total litter size for primiparous females (9.1 ± 0.4) was lower (P = 0,0004) than for parity-2 and -3 females (11.5 ± 0.5 e 11.5 ± 0.2, respectively). There was a significant effect of an interaction between treatment and parity on total litter size (P < 0.05), generally characterized by the occurrence of lower litter sizes for PCAI in primiparous females than for other treatment by parity combinations. In conclusion, reproductive performance for PCAI and ICAI were similar with sperm concentrations up to 1 x 10 9 spermatozoa per dose. / A inseminação artificial (IA) é uma biotécnica reprodutiva que vem sendo intensamente utilizada na suinocultura, em função dos benefícios genéticos e sanitários, permitindo que as agroindústrias coloquem no mercado produtos saudáveis e de qualidade. A técnica de IA pós-cervical (IAPC) possibilita a deposição do sêmen no corpo do útero, utilizando doses inseminantes com de 1 x 10 9 espermatozóides/dose. Portanto, com a IAPC, a fertilidade do reprodutor utilizado como doador de sêmen, passa a influenciar o desempenho reprodutivo de um número três vezes maior de fêmeas, quando comparado a IA convencional. Este estudo teve como objetivo comparar o desempenho reprodutivo de fêmeas suínas submetidas a IAIC, com dose inseminante convencional com a IAPC com 3 diferentes concentrações (2; 1; e 0,5 x 10 9 espermatozóides/ dose). O estudo incluiu 338 fêmeas F1, sendo que, 232 fêmeas receberam a primeira dose inseminante 12 h após a detecção de cio e as doses subseqüentes em intervalos de 12 h, enquanto 106 fêmeas foram inseminadas imediatamente após a ovulação, confirmada por ultra-sonografia em tempo real. Taxas de concepção e parição (TPAR) para a IAIC (98,9% e 97,9%, respectivamente), foram maiores (P < 0,001) às observadas para a IAPC (87,1% e 84,3%, respectivamente). Tanto para taxa de concepção como TPAR, os índices observados para o T8 foram numericamente inferiores aos demais tratamentos, porém sem diferença significativa ( P > 0,05). O total de leitões nascidos por parto não diferiu entre os tratamentos (P = 0,09). Para as fêmeas com 1, 2 , 3 ou mais partos, a TPAR foi igual a 90,2%, 82,7% e 88,9% (P = 0,40). No entanto, o total de leitões nascidos foi influenciado pela ordem de parto (OP) das matrizes, sendo inferior (P = 0,0004) para fêmeas primíparas (9,1 ± 0,4) do que para fêmeas com 2 e 3 ou mais partos (11,5 ± 0,5 e 11,5 ± 0,2, respectivamente). Também houve interação entre o efeito dos tratamentos e a OP com relação ao tamanho de leitegada, pois a resposta foi inferior (P < 0,05) em fêmeas primíparas em alguns dos tratamentos com IAPC. Com isso, podemos concluir que o método de IAPC, em condições de rotina em uma granja comercial, atingiu índices de desempenho reprodutivo semelhantes quando comparado com o IAIC, com doses de até 1 x 10 9 espermatozóides.

The capture of neonate ungulates has played an integral role in studies of habitat selection, phenology, survival, and other topics of ecological interest. However, neonates can be difficult for researchers to locate and capture. Neonate ungulates are born in habitats with reduced visibility, frequently spend time in a concealed, prone position, and may display cryptic coloration. In an attempt to improve researchers' likelihood of locating and capturing neonate ungulates, multiple capture methods have been developed. Much remains unknown about biases associated with capture methods and how to further improve capture methods once biases are understood. Our objectives were to determine if opportunistic captures of neonate mule deer (Odocoileus hemionus) bias estimates of litter size (Chapter 1) and to determine when searches for neonate elk (Cervus canadensis) should begin following parturition to maximize likelihood of capture while minimizing disturbance (Chapter 2). To complete our objectives, we analyzed data from 161 litters of mule deer and 55 attempted captures of neonate elk during 2019-2021 in Utah, USA. Estimates of litter size derived from opportunistic captures of mule deer were smaller than estimates derived from movement-based captures or captures completed with the aid of vaginal implant transmitters (VITs). The time elapsed between parturition and when searches were initiated for neonate mule deer did not influence estimates of litter size, but we could only analyze this relationship for VIT-aided captures within approximately 2 days of parturition. Until more data are available, we recommend that estimates of litter size for neonate mule deer be completed using movement-based or VIT-aided captures within approximately 2 days of parturition. When attempting to capture neonate elk, reducing the time elapsed between parturition and when searches were initiated resulted in a decreased search length, decreased distance traveled by the neonate, and increased likelihood of capture. We initiated searches as early as 3.6 hours post-parturition with no evidence of maternal abandonment and probability of capture was near or above 90% when searches were initiated within 10 hours of parturition. We recommend that searches for neonate elk be initiated 3.6-10 hours post-parturition. Future researchers can use utilize our results to perform captures of neonate ungulates that minimize bias, decrease disturbance, increase efficiency, and maximize the likelihood of capture success.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Animal traits differ not only in mean, but also in variation around the mean. For instance, one sire’s daughter group may be very homogeneous, while another sire’s daughters are much more heterogeneous in performance. The difference in residual variance can partially be explained by genetic differences. Models for such genetic heterogeneity of environmental variance include genetic effects for the mean and residual variance, and a correlation between the genetic effects for the mean and residual variance to measure how the residual variance might vary with the mean. The aim of this thesis was to develop a method based on double hierarchical generalized linear models for estimating genetic heteroscedasticity, and to apply it on four traits in two domestic animal species; teat count and litter size in pigs, and milk production and somatic cell count in dairy cows. The method developed is fast and has been implemented in software that is widely used in animal breeding, which makes it convenient to use. It is based on an approximation of double hierarchical generalized linear models by normal distributions. When having repeated observations on individuals or genetic groups, the estimates were found to be unbiased. For the traits studied, the estimated heritability values for the mean and the residual variance, and the genetic coefficients of variation, were found in the usual ranges reported. The genetic correlation between mean and residual variance was estimated for the pig traits only, and was found to be favorable for litter size, but unfavorable for teat count.

The aim of the thesis was to reveal reserves for improving the piglets breeding and to reduce losses by death. The highest number of all (13.52 pcs) and live born (11.88 pcs) piglets were achieved in gilts embedded in more than 247 days of age. Gilts covered within 224 days of age showed the lowest average number of piglets born (13.13 pcs). Statistically, however, has not been demonstrated difference (p > 0.05) between age groups of gilts during the first recess in the number of piglets born. Effect of order of litter on litter size was found to be statistically highly significant (p < 0.01), especially between the first and third parturition. The highest number of born piglets was found on the third litter (14.95 pcs) and lowest in the first litter (13.3 pcs). Most live piglets born were at the second litter (14.03 pcs) and least live born piglets were found on the 5th and higher litter (11.57 pcs). Among the number of piglets born alive in the individual litters was also evaluated statistically highly significant difference (p < 0.01). In assessing the impact on the duration of labor litter size was found to be a higher number of piglets born at night on average by 0.33 piglet more, but the number of piglets born alive was found higher in childbirth during the day (childbirth with assist). During statistical evaluation was not demonstrabled difference between the number of all even in the case of piglets born alive in viewpoint of the time of birth. From the perspective of the impact of the length of the interval from weaning to sows on litter size was found to be a higher number of all (14.83 pcs) and live (12.79 pcs) piglets born of sows recessed for more than 6 days after weaning. From the viewpoint of the impact sequence of litter for childbirth was detected statistically detectable difference (p > 0.05). In each of the litters was observed an average of 75 % births through the day. When evaluating the number of live births, depending on the number of piglets, born piglets showed a statistically highly significant relationship (p < 0.01) with high tightness on dependence (R = 0.83). Between the number of all born piglets and born alive was found a direct correlation.