Avaliou-se a influência do desenvolvimento corporal na ciclicidade, na resposta ovariana e na taxa de prenhez à inseminação artificial em tempo fixo (IATF) de novilhas da raça Nelore ao sobreano (Experimento 1). Ainda, avaliou-se a eficiência de um protocolo de indução de ciclicidade (Experimento 2) previamente ao protocolo de IATF. No Experimento 1, 650 novilhas de 13,9&#177;0,03 meses de idade foram submetidas ao mesmo protocolo de sincronização da ovulação para IATF. Dez dias antes do início do protocolo de sincronização (Dia -10), as novilhas foram avaliadas quanto à idade (meses), peso (kg), escore de condição corporal (ECC, escala de 1 a 5), altura de cernelha (hCERN, cm) e relação altura/profundidade de costela (pCOST,% ) escore do trato reprodutivo (ETR, escala de 1 a 5), ciclicidade (presença de CL) e espessura de gordura subcutânea na garupa (EGPU, mm). No Dia 0, as fêmeas foram submetidas a sincronização da ovulação, recebendo IATF 10 dias após (Dia 10). Foram determinados por ultrassonografia a taxa de ciclicidade (presença de CL no Dia -10 e/ou Dia 0) os diâmetros do maior folículo presente no Dia 8 (FDD8), no Dia 10 (FDIA), presença de CL no Dia 17 (ovulação) e taxa de prenhez 30 dias após a IATF. Com relação à análise univariável, não houve diferença na taxa de ciclicidade com relação à hCERN e pCOST (P&gt;0,05), mas isoladamente a idade, o peso, o ECC e a EGPU foram associados com incremento na taxa de ciclicidade (P&lt;0,05). Entretanto, na análise multivariável o parâmetro retido no modelo foi a EGPU (&gt;3,4mm; 19,4 vs. &le;3,4mm; 8,8%; P=0,002). O FDD8 não foi influenciado pela idade, ECC e pCOST (P&gt;0,05) quando analisados de maneira isolada. Entretanto, o peso, hCERN, EGPU e ETR foram associados com maior FDD8 (P&lt;0,05). Contudo, ao se avaliar todos os parâmetros de maneira conjunta, houve efeito de hCERN (&gt;121,5=7,2 vs. &le;121,5=6,9mm; P=0,03), EGPU (&gt;2,6=7,4 vs. &le;2,6=6mm; P=0,02) e ETR (1=6,9ab;2=7,4ab; 3=7,1ab; 4=7,7ª; 5=6,3mmb; P=0,002) sobre o FDD8. O CrescFD e a taxa de ovulação não foram influenciados por nenhum dos parâmetros avaliados, em ambas as análises (P&gt;0,05). Ainda, na análise univariável a hCERN e o ETR (P&gt;0,05) não resultaram em efeito na taxa de prenhez, mas a idade, o peso, o ECC, a pCOST e a EGPU foram associados com incremento no sucesso gestacional (P&lt;0,01). Entretanto, ao se utilizar a análise multivariável os parâmetros retidos no modelo foram a idade (&gt;13,8=43,0 vs. &le;13,8=27,2; P=0,04), a pCOST (&gt;44,0=41,9 vs. &le;44,0=27,0; P = 0,02) e a EGPU (>2,5=44,4 vs. &le;2,5=23,4%; P=0,0003). No Experimento 2, 626 novilhas de 14,2±0,03 meses de idade foram aleatoriamente distribuídas em dois grupos experimentais: Indução (n=307; dispositivo de P4 usado durante 10 dias mais 0.6mg de CE no momento da retirada) e Controle (n=319). Doze dias após a retirada do dispositivo de P4 (Dia 0) todas as fêmeas foram submetidas a protocolo de sincronização para IATF conforme descrito no Experimento 1. As novilhas que receberam o protocolo de indução tiveram maior (P<0,0001) taxa de ciclicidade (75,2%) no Dia 0 em relação ao controle (7,8%). Entretanto, semelhante taxa de prenhez à IATF foi verificada entre os tratamentos (Controle 42,9 vs. Indução = 43,0%; P=0,40). Conclui-se que os parâmetros de desenvolvimento corporal apresentam relação positiva com a ciclicidade e a resposta ao protocolo para IATF em novilhas raça Nelore ao sobreano. Além disso, o estímulo hormonal prévio aumentou a proporção de novilhas com CL no início do protocolo de IATF, entretanto, não influenciou a taxa de prenhez à inseminação artificial / The influence of body development on ciclicity, ovarian response and pregnancy rate after timed artificial insemination (TAI) was evaluated in yearling Nelore beef heifers (Experiment 1). Furthermore, the efficiency of a protocol for ciclicity induction, previously to the TAI was tested (Experiment 2). At Experiment 1, 650 heifers aged 13,9 ± 0.03 months were submitted to the same ovulation synchronization protocol for TAI. Ten days before the beginning of the TAI protocol (Day -10), all females were evaluated for age (months), weight (kg), body condition score (BCS, 1 to 5 scale), withers height (hCERN, cm) and whiters height/depth of rib relationship (pCOST, %), reproductive tract score (RTS, 1 to 5 scale) ciclicity (presence of a CL) and subcutaneuos fat thickness (EGPU, mm). At Day 0, all heifers were submitted to the ovulation synchronization, receiving TAI after 10 days (Day 10). The ciclicity (presence of a CL at Day -10 and/or Day 0), diameter of the biggest follicle at Day 8 (FDD8) and Day 10 (FDIA) as the ovulation rate at Day 17 and pregnancy rate at Day 30 were determined by ultrassonography. In relationship to the univariable analysis, there was no difference of ciclicity rate according to hCERN and pCOST (P>0.05), but age, weight, BCS, and EGPU were associated to greater ciclicity (P<0.05). However, considering the multivariable analysis, heifers with greater EGPU (>3.4mm; 19.4%) presented greater (P=0.002) ciclicity rate in comparison to heifers with lesser EGPU ( &le;3.4mm; 8.8%). The FDD8 was not influenced by age, BCS and pCOST (P>0.05) and was influenced by hCERN, EGPU and RTS when the variables were singly analyzed. Nevertheless, there was an effect of hCERN (>121.5=7.2 vs. &le;121.5=6.9; P=0.03), EGPU (>2.6=7.4 vs. &le;2.6=6.0; P=0.02) and RTS (1=6.9ab; 2=7.4ab; 3=7.1ab; 4=7.7ª; 5=6.3 mmb; P=0.002) over the FDD8, when all variables were analyzed together. The ovulation rate was not influenced by any of the evaluated parameters (P>0.20). Still, considering the univariable statistical model, there was no effect of hCERN and RTS (P=0.05) on pregnancy rate, but age, weight, BCS, pCOST and EGPU were associated with increased pregnancy rate to TAI (P<0.05). Still, heifers with more age (>13.8=43.0 vs. &le;13.8=27.2; P=0.04), greater pCOST (>44.0=41.9 vs. &le;44.0=27.0%; P = 0.02) and greater EGPU (>2.5=44.4 vs.&le;2.5mm=23.4%; P=0.0003) presented greater pregnancy rate when all varaiables were analyzed together. At Experiment 2, 626 heifers aged 14.2±0.03 months were randomly allocated in two experimental groups: Induction (n=307; used P4 device during 10 days plus 0.6mg EC at device removal) and Control (n=319). Twelve days after P4 device removal (Day 0) all females were submitted to the same ovulation synchronization protocol described in Experiment 1. Heifers from Induction group (75.2%) had greater (P<0.0001) ciclicity rate at Day 0 in comparison to Control (7.8%), but similar pregnancy rate to 1st TAI (Control 42.9 vs. Induction 43.0%; P=0.40). It is concluded that the body developmental parameters presents positive relationship with ciclicity and response to the TAI protocol in Nelore yearling heifers. Moreover, a previous hormonal stimulus increases the proportion of heifers with a corpus luteum at the beginning of the TAI protocol, but does not affect pregnancy rate to the artificial insemination

O presente trabalho teve por objetivo investigar a variação na secreção de LH em resposta ao tratamento com neurotransmissores, na presença ou não de esteróides gonadais e desta forma gerar informações sobre os mecanismos neuroendócrinos envolvidos na maturação sexual de novilhas da raça Nelore. A concentração de LH foi quantificada por radioimunoensaio e as novilhas ovariectomizadas (OVX) apresentaram maior concentração basal de LH (P&le;0,05), que as novilhas inteiras (INT). A administração de um antagonista gabaérgico (picrotoxina, 0,18 mg/kg, iv, amostras 15 min por 10 h) aos 8, 10, 14 e 17 meses de idade, aumentou (P&le;0,05) a concentração média e área total de secreção de LH nas novilhas INT tratadas aos 14 meses, a área total dos picos e área do maior pico de secreção de LH foi maior (P&le;0,05) nas novilhas OVX aos 14 e 17 meses de idade . A administração de um antagonista dopaminérgico (sulpiride, 0,59 mg/kg, sc, amostras 15 min por 10 h) aos 8, 12 e 16 meses de idade diminuiu (P&le;0,05) a secreção de LH (concentração média, área total, área total dos picos e área do maior pico secreção de LH) nas novilhas OVX aos 8 meses de idade. A administração de um estimulador alfa-adrenérgico (clonidina, 10 µg/kg, iv, amostras 15 min por 4 h) aos 8, 12 e 15 meses de idade, diminuiu (P&le;0,05) o número de picos nas novilhas OVX com 8 meses de idade. A administração do 17&beta;-estradiol (2 µg/kg, iv, amostra 15 min por 3 h, 1 h por 7 h e 3 h por 22 h) aos 10, 13 e 17 meses de idade diminuiu a diferença (P&ge;0,05) entre os grupos OVX e INT em relação ao número de picos, área total de picos, área do maior pico e tempo necessário para acontecer o maior pico. Foi avaliada a secreção de LH da desmama à primeira ovulação em novilhas INT e OVX. A concentração de LH aumentou durante a maturação sexual, tanto nas novilhas INT quanto nas OVX. O número de picos de secreção de LH e amplitude máxima de secreção de LH foi maior (P&le;0,05) nas novilhas OVX com o aproximar da primeira ovulação. Os resultados indicam uma diminuição da sensibilidade do hipotálamo aos esteróides gonadais durante o processo de maturação sexual nas novilhas da raça Nelore e a participação alternada de neurotransmissores, inibindo e estimulando a secreção de LH. Concluímos que, em novilhas pré-púberes da raça Nelore o desenvolvimento da retroalimentação positiva aos esteróides gonadais no hipotálamo foi importante para aumentar a secreção de LH antes da primeira ovulação, com a participação de neurotransmissores estimulando ou inibindo a secreção de LH. / The variation on LH secretion after neurotransmitter administration, on the presence or absence of gonadal steroid, was investigated, generating information about the mechanisms evolved on sexual maturation in Nellore heifers. LH concentration was quantified by RIA. As expected ovariectomized heifers higher basal LH concentration (P&le;0,05) than intact heifers. The picrotoxin administration (GABA antagonist, 0,18 mg/kg, iv, samples 15 min for 10 h) at 8, 10, 14 and 17 months of age increased (P&le;0,05) average concentration and total secretion area on intact treated heifers at 14 months and peak total area and area of highest peal on ovariectomized heifers at 14 and 17 months of age. The dopaminergic antagonist (sulpiride, 0.59 mg/kg, sc, sample 15 min for 10 h) administrated at 8, 12 and 16 months of age decreased (P&le;0,05) LH secretion (average levels, total peak area and area of the highest secretion peak) on ovariectomized heifers at 8 months of age. The administration of an alfa-adrenérgic stimulatory (clonidine 10 µg/kg, iv, samples 15 min for 4 h) at 8, 12 and 15 months of age decreased (P&le;0,05) decreased the number of peaks at 8 months of age. 17&beta;-estradiol administration (2 µg/kg, iv, samples every 15 min for 3 h, every 1 h for 7 h and every 3 h for 22 h) decreased the differences between ovariectomized and intact heifers on number of peaks, total peak area, highest peak area and time to highest peak occurrence. The LH secretion from weaning to first ovulation in non treated intact and ovariectomized heifers was also evaluated. LH concentration increase during sexual maturation in both ovariectomized and intact heifers. The number of peaks, and maximum LH secretion amplitude was higher in ovariectomized heifer closest to first ovulation, when compared to intact heifers. The results suggested a decrease on hipothalamus sensitivity to gonadal steroid during the sexual maturation in Nelore heifer associated with neurotransmitter participation either stimulating or inhibiting LH secretion. It was possible to conclude that the decrease of negative feedback associated with the increase on positive feedback of gonadal steroids over hipothalamus was necessary to increase LH secretion before first ovulation, that was associated with neurotransmitter participation on LH secretion.

In biennial following (spring 2005, autumn 2005, spring 2006, autumn 2006) we're rasitology examine 288 samples dropping from heifers and 288 samples dropping from bulls. Exhibits we're examined floatation in Sheather´s sugar solution. In examinate dropping we're proved present cysts Giardia intestinalis and oocysts Cryptosporidium andersoni and family Eimeria. In heifers was most frequent parasites coccidia Eimeria sp. (28,5 %). Flagellata Giardia intestinalis occur in 17 % of all designs. At least we're open up Cryptospordium andersoni (9,4 %). In bulls we're noted highest occurrence coccidia Eimeria sp. (19,1 %). Almost same occurrence we're found out near Giardia intestinalis (18,8 %). Very low prevalence we're have observed near Cryptosporidium andersoni (1,4 %).

The aim of this thesis was to evaluate the parameters of the milk performance, reproduction indicators and health of Holstein cows that were raised on pasture at ŠZP (School agriculture company) Haklovy Dvory. Monitoring is carried out in the years 2011 - 2013. The work involved two groups bred cows grazed in total 56. In 2012 it was 27 cows and in 2013 29 cows. The control group which was represented by 20 heifer which had been reared in stable in years 2010-2011 the number 20 Holstein cows. The evaluation of parameters was set on the first standardized lactation in the range of 240 to 305 days. Into observation of reproductive indicators was included the age of the first calving (days), insemination interval (days) and servis period (days). From the productive indicators there was the quantity of milk (kg), the content of fat in the milk (%), quantity of fat in the milk (kg), and the content of proteins.

Made available in DSpace on 2014-06-11T19:35:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-14Bitstream added on 2014-06-13T21:07:25Z : No. of bitstreams: 1 abba_mg_dr_botfmvz.pdf: 446368 bytes, checksum: 2cfd728ce5907ab74df1ee7c33c75b0f (MD5) / Universidade Estadual Paulista (UNESP) / O presente trabalho tem como objetivo avaliar o ganho de peso e características de carcaça, em novilhas cruzadas (1/4 Simental e Nelore) usando um método experimental de esterilização, que consiste na introdução de esferas inoxidáveis. O experimento teve início em 19/03/2004, data em que foram pesadas 100 novilhas nulíparas, destinadas ao abate, com idades variando entre 12 e 24 meses e com peso médio de 275 kg. Todos os animais receberam o mesmo manejo alimentar, em sistema de pastejo em Brachiaria brizantha, água e sal mineral ad libitum e foram pesados a intervalos de 28 dias, obedecido o jejum prévio de 16 horas. Os animais foram divididos aleatoriamente em quatro grupos experimentais: G1 - Grupo de novilhas testemunhas: G2 - grupo de novilhas esterilizadas mais aplicação de modificador orgânico Leivas Leite ®; G3 - grupo de novilhas esterilizadas: e G4 - grupo de novilhas não esterilizadas com aplicação de modificador orgânico Leivas Leite ®. Foram introduzidas12 (doze) esferas de aço inoxidável previamente esterilizadas no útero de cada novilha. Todos os animais foram abatidos e analisados quanto: ganho de peso, peso da carcaça quente, cobertura de gordura e rendimento da carcaça, e exames laboratoriais para as avaliações sensoriais da carne: área de olho de lombo; espessura da gordura e maciez. Através do presente trabalho em função dos resultados obtidos pode-se concluir que: O maior ganho de peso e a carne mais macia foi obtida do grupo de animais do Grupo 2 (G2) - novilhas esterilizadas, mais aplicação de modificador orgânico LEIVAS LEITE®, e como a maciez da carne é um dos itens mais valorizados por consumidores, recomenda-se este método aos pecuaristas. / In this work we propose evaluate the gain of weight and characteristics of carcass in crusade heifer (1/4 Simental e Nelore) by using an experimental method of castration, what consists on introduction of stainless globes, intra-uterine (I.E.I.U.). The experiment began in 19/03/2004, date in which 100 heifers nulliparous destined to cattle were weighted, with ages between 12 and 24 months and with middleweight of 275 kg. All animals received the same alimentary handling, in pastry system of Brachiaria Brizanthus, e were weight in intervals of 28 days, submitted a 16 hours earlier abstinence of food. Considering the reproduction sanity, the weight and the age, the animals were randomly divided into four experimental groups: G1- group of testifies heifers, G2- group of sterilized heifers more application of organic modifier Leivas Leite®, G3- group of sterilized heifers, G4- group of non sterilized heifers more application of organic modifier Leivas Leite® Using the universal applicator of artificial insemination, 12 (twelve) stainless steel globes earlier sterilized (with diameter of approximately 3 mm) have been introduced into the uterine of each heifer. All animals have been cattle and analyzed regarding: weight gain, hot carcass weight, fat cover, and carcass profit. After pieces cooling, sampling of the meet were colleted and sent to laboratorial examination to sensorial evaluation of the meet: loin eye area, fat thickness, smoothness. Through the present work the obtained results can be conclude that: The largest weight earnings and the softest meat was obtained of the group of animals of the Group 2 (G2) - sterilized heifers, plus addition of organic modifier LEIVAS LEITE®, and as the softness of the meat it is one of the terms more valued by consumers, this method is recommended to the cattle farmers.

Master of Science / Department of Animal Sciences and Industry / Karol Fike / The United States beef cattle industry is continuously evolving and changing to meet buyer demands while considering environment factors for production. Cow-calf producers make decisions within their herds that impact their profitability. Previous research shows producers can add value to beef calves through management and marketing decisions in areas such as genetics, herd health, and nutrition. It is well documented that there are numerous factors that influence the sale price of beef calves, no matter the venue through which they are sold. Historically, steer calves sold for a greater price compared to heifer calves. Apparent breed composition also influences value of lots of beef calves. Black-hided calves recently sold for a greater sale price than calves of other hide colors due to perceived differences in potential performance. Calves with Bos indicus influence usually sell for a lower price than other breed types. Marketing of beef calves through video auction allows sellers to market lots of calves to a buyer basis nationwide. A national market provides a basis for buyer preferences and potential national trends for changes in characteristics valued by buyers. Evaluation of national breed composition trends can indicate potential changes in the industry. The opportunity to evaluate if and how breed description as described by producers influenced calf sale price from 1995 through 2016 was available through a livestock video auction service. Chapter 1 is a review of the literature and an overview of the beef industry and factors affecting sale price of lots of beef calves. Chapter 2 is an analysis of breed composition influencing sale price for lots of steer calves and lots of heifer calves. Chapter 3 investigates national and regional breed description and sire breed trends over a 23-year period.

Orientador: Wilter Ricardo Russiano Vicente / Banca: Sony Dimas Bicudo / Banca: Nereu Carlos Prestes / Banca: Rodolfo Cláudio Spers / Banca: Cledson Augusto Garcia / Resumo: O presente trabalho tem como objetivo avaliar o ganho de peso e características de carcaça, em novilhas cruzadas (1/4 Simental e Nelore) usando um método experimental de esterilização, que consiste na introdução de esferas inoxidáveis. O experimento teve início em 19/03/2004, data em que foram pesadas 100 novilhas nulíparas, destinadas ao abate, com idades variando entre 12 e 24 meses e com peso médio de 275 kg. Todos os animais receberam o mesmo manejo alimentar, em sistema de pastejo em "Brachiaria brizantha", água e sal mineral "ad libitum" e foram pesados a intervalos de 28 dias, obedecido o jejum prévio de 16 horas. Os animais foram divididos aleatoriamente em quatro grupos experimentais: G1 - Grupo de novilhas testemunhas: G2 - grupo de novilhas esterilizadas mais aplicação de modificador orgânico Leivas Leite ®; G3 - grupo de novilhas esterilizadas: e G4 - grupo de novilhas não esterilizadas com aplicação de modificador orgânico Leivas Leite ®. Foram introduzidas12 (doze) esferas de aço inoxidável previamente esterilizadas no útero de cada novilha. Todos os animais foram abatidos e analisados quanto: ganho de peso, peso da carcaça quente, cobertura de gordura e rendimento da carcaça, e exames laboratoriais para as avaliações sensoriais da carne: área de olho de lombo; espessura da gordura e maciez. Através do presente trabalho em função dos resultados obtidos pode-se concluir que: O maior ganho de peso e a carne mais macia foi obtida do grupo de animais do Grupo 2 (G2) - novilhas esterilizadas, mais aplicação de modificador orgânico LEIVAS LEITE®, e como a maciez da carne é um dos itens mais valorizados por consumidores, recomenda-se este método aos pecuaristas. / Abstract: In this work we propose evaluate the gain of weight and characteristics of carcass in crusade heifer (1/4 Simental e Nelore) by using an experimental method of castration, what consists on introduction of stainless globes, intra-uterine (I.E.I.U.). The experiment began in 19/03/2004, date in which 100 heifers nulliparous destined to cattle were weighted, with ages between 12 and 24 months and with middleweight of 275 kg. All animals received the same alimentary handling, in pastry system of "Brachiaria Brizanthus", e were weight in intervals of 28 days, submitted a 16 hours earlier abstinence of food. Considering the reproduction sanity, the weight and the age, the animals were randomly divided into four experimental groups: G1- group of testifies heifers, G2- group of sterilized heifers more application of organic modifier Leivas Leite®, G3- group of sterilized heifers, G4- group of non sterilized heifers more application of organic modifier Leivas Leite® Using the universal applicator of artificial insemination, 12 (twelve) stainless steel globes earlier sterilized (with diameter of approximately 3 mm) have been introduced into the uterine of each heifer. All animals have been cattle and analyzed regarding: weight gain, hot carcass weight, fat cover, and carcass profit. After pieces cooling, sampling of the meet were colleted and sent to laboratorial examination to sensorial evaluation of the meet: loin eye area, fat thickness, smoothness. Through the present work the obtained results can be conclude that: The largest weight earnings and the softest meat was obtained of the group of animals of the Group 2 (G2) - sterilized heifers, plus addition of organic modifier LEIVAS LEITE®, and as the softness of the meat it is one of the terms more valued by consumers, this method is recommended to the cattle farmers. / Doutor

Submitted by (edna.saturno@ufrpe.br) on 2016-10-11T15:07:57Z No. of bitstreams: 1 Humberto Fernandes Veloso Neto.pdf: 1107273 bytes, checksum: 67f2862b222caf4332afe8d16b522184 (MD5) / Made available in DSpace on 2016-10-11T15:07:57Z (GMT). No. of bitstreams: 1 Humberto Fernandes Veloso Neto.pdf: 1107273 bytes, checksum: 67f2862b222caf4332afe8d16b522184 (MD5) Previous issue date: 2013-02-22 / The variability of successful transfers of embryos produced in vitro is still one of the obstacle to its expansion, where some of the problems are related to early embryonic mortality. The aim of this work was to evaluate the application of flunixin meglumine and recombinant bovine somatotropin and observe the effect of variables such as embryonic development, embryo synchrony with the recipient, corpus luteum size at the time of transfer and pregnancy rate. In the first experiment 55 recipient heifers were randomly in the three different groups: G1 control group (n=15 animals); G2 group receiving 500mg of recombinant bovine somatotropin (bST)/animal/subcutaneous (n=20 animals) and G3 group receiving 500mg flunixin meglumine/animal/intramuscular (n=20 animals). Pregnancy rates for G1 53,33% (8/15), G2 60% (12/20), G3 55% (11/20) with no statistically significant difference between groups (P> 0,05). In experiment II 134 heifers were used as recipients of embryos produced in vitro. The pregnancy rate was evaluated according to the degree of development of the structure transferred embryo synchrony with the receiver, and corpus luteum size. Embryos (blastocyst, expanded blastocyst, ecloded blastocyst) showed better pregnancy rates than less development younger embryos (morula, early blastocyst), 57,14% and 25% respectively (P<0,05). Synchrony with the recipient embryo -1 (68,42%), 0 (88,88%), +1 (41,5%) for P<0,05 and size of the corpus luteum large 46,83% CL1, CL2 average 55,88%, 42,85% CL3 small (P> 0,05). In conclusion, under experiment conditions described, the application of flunixin meglumine, recombinant bovine somatotropin and was not efficient to increase the pregnancy rate, but it is note that the pregnancy rate varied in the degree of development of the embryo and the embryo synchrony with the recipient. / A variabilidade do sucesso das transferências de embriões produzidos in vitro ainda é um dos entraves para sua expansão, onde alguns dos problemas são relacionados à mortalidade embrionária precoce. O objetivo com estes trabalhos foi avaliar a aplicação da flunixina meglumina e da somatotropina recombinante bovina e observar o efeito de algumas variáveis como grau de desenvolvimento do embrião, sincronia do embrião com a receptora e classificação do corpo lúteo da receptora no momento da transferência sobre a taxa de prenhez. No experimento I foram utilizadas 55 novilhas receptoras de embrião agrupadas aleatoriamente: G1 grupo controle (n=15animais); G2 grupo que recebeu 500mg de somatotropina recombinante bovina/animal/por via subcutâneo (n=20 animais) e G3 grupo 500mg de flunixina meglumina/animal/via intramuscular (n=20 animais). As taxas de prenhez para os grupos foram G1 53,33% (8/15), G2 60% (12/20), G3 55% (11/20) não havendo diferença significativa entre os grupos (P>0,05). No experimento II foram utilizadas 134 novilhas como receptoras de embriões produzidos in vitro. A taxa de prenhez foi avaliada segundo grau de desenvolvimento da estrutura transferida, sincronia do embrião com a receptora e a classificação corpo lúteo. Embriões desenvolvidos (Blastocisto, Blastocisto expandido) apresentaram melhores índices de prenhez que embriões jovens (Mórula, Blastocisto inicial), 57,14% e 25% respectivamente (P<0,05). Sincronia do embrião com a receptora que apresentou melhores taxas de prenhez foram: sincronia 0 (88,88%) e sincronia - 1 (68,42 %) em relação a sincronia + 1 (41,5 % ) para P<0,05 e classificação do corpo lúteo não houve diferença com CL1 grande 46,83%, CL2 médio 55,88%, CL3 pequeno 42,85% (P>0,05). Nas condições deste experimento a aplicação da flunixina meglumina e da somatotropina recombinantes bovina não foi eficiente para aumentar a taxa de prenhez, porém deve-se atentar que a taxa de prenhez foi dependente do grau de desenvolvimento do embrião e sincronia da receptora com o embrião.

Master of Science in Veterinary Biomedical Science / Department of Clinical Sciences / Robert L. Larson / The selection of young replacement animals can have a significant impact on beef herd reproductive performance. Replacement heifers can be utilized to improve reproductive performance by replacing mature animals that failed to meet the production with young, cycling heifers that can have the potential of improving the reproductive momentum of a herd. The use of yearling bulls in natural breeding herds has the advantage of shortening the generational interval of the herd and has the potential of reducing the cost per cow exposed as additions to the bull battery. This thesis involves two studies that investigated methods used for the selection of peripubertal replacement animals in beef herds. The first study evaluated the ability of the novel Ready-Intermediate-Problem (RIP) replacement heifer evaluation matrix to classify heifers into groups that allow producers to select for replacements that meet production goals. Beef heifers (n=341) were classified according to the RIP matrix guidelines and then exposed to AI breeding, bull breeding, or a combination of both as per the management plans for each participating herd. Following breeding season the heifers were evaluated to determine pregnancy status, pregnancy status to single AI exposure, days bred, and the number of 21 day cycles needed during breeding season to become pregnant. After breeding season, 298 (87%) of the heifers were pregnant, 204 (68%) of which became pregnant in the first 21 days of the breeding season. Probability of overall pregnancy and pregnancy after single AI exposure was not significantly associated with RIP classification. There was a significant interaction in RIP classification by 21 day cycle. The second study was a retrospective study using BSE result data to determine the proportion of yearling beef bulls that are classified as satisfactory potential breeders when reevaluated after failing their initial breeding soundness evaluation (BSE) and to identify any predictive factors at initial BSE for satisfactory performance at revaluation. The study included 2,805 beef bulls between 11 and 14 months of age at first BSE evaluated at KABSU from 2006 to 2014. Generalized linear mixed models were created to assess potential associations among breed, age, and interaction between breed and age and passing the initial evaluation and identify predictive factors for risk of passing BSE after initial failure. The majority (93%) of the study bulls passed one of up to three BSEs. There was a significant interaction between age and breed of bull at initial BSE. Identification of suitable peripubertal replacement animals that will improve herd reproductive performance remains a challenge for producers. There are several factors that can affect replacement animals’ ability to perform according to expectations at the beginning of the breeding season. Classification of heifers into categories that can predict performance during breeding season with reasonable confidence can assist producers in identifying heifers that complement the reproductive performance goals of the herd. Utilizing BSE to identify bulls that have adequate semen quality as well as other traits important for breeding soundness is similarly important in reducing the risks of using young bulls for breeding.

Les traitements anthelminthiques (AH) visant à maîtriser l’impact des strongles gastro-intestinaux (SGI) sur la croissance des jeunes bovins doivent être rationnalisés afin de préserver durablement leur efficacité. L’objectif de cette thèse a été de développer et d’évaluer des stratégies de traitement ciblé sélectif (TCS) basées sur la croissance chez les génisses laitières de première saison de pâturage afin de préserver des populations refuges de SGI, non exposées aux AH, et ainsi de retarder l’apparition de résistance. La relation croissance/parasitisme en fin de saison a tout d’abord été étudiée dans des environnements variés ce qui a permis d’appréhender des lots plus infestés et, à l’intérieur de ces lots, des individus plus fortement infestés. Un arbre de décision de traitement de rentrée a été ensuite proposé en combinant des indicateurs de conduite au pâturage pour identifier les groupes à risque et plusieurs seuils de GMQ pour identifier les animaux souffrant le plus du parasitisme. Une stratégie de TCS basée sur le GMQ moyen réalisé à mi- saison a été évaluée sur le terrain par comparaison avec un traitement collectif. Aucune différence significative, en termes de croissance et de parasitisme, n’a été observée à la rentrée entre le groupe TCS et le groupe traité collectivement. Enfin, les attitudes et les perceptions des vétérinaires vis-à-vis du contrôle des parasitoses digestives en élevage bovin laitier et notamment d’une gestion plus raisonnée des anthelminthiques, ont été évaluées. Les vétérinaires reconnaissent la nécessité d’appréhender les traitements AH de manière raisonnée mais identifient de nombreux freins relatifs au développement du conseil et à la disponibilité d’outils simples, fiables et peu couteux. Les résultats de cette thèse montrent qu’il est possible de cibler l’utilisation des AH chez les génisses laitières de première saison de pâturage en se basant sur des indicateurs individuels et de groupe simples d’emploi. / In first grazing season calves (FGSC), the anthelmintic (AH) treatments used to control the negative impact of gastrointestinal nematodes (GIN) on growth must be rationalized to preserve their long-term efficacy. The aim of this PhD thesis was to develop and assess targeted selective treatment (TST) strategies based on growth in FGSC, in order to preserve GIN populations in refugia i.e. not exposed to AH, and thus delay the emergence of AH resistance. Firstly, the relation growth/GIN infection at housing was demonstrated in different environments which allowed identifying groups, and within groups, the most infected animals. Then, a tree treatment decision at housing was proposed combing grazing management indicators to identify the groups at risk, and several average daily weight gain (ADWG) thresholds to identify, within groups, the animals suffering the most of infection. A TST strategy based on mid- season mean ADWG was assessed in field survey in comparison with whole group treatment (WGT). No significant difference, in terms of growth and GIN infection, was observed at housing between the TST and the WGT groups. Lastly, the veterinarians’ behaviors and perceptions about the control of GIN in dairy cattle farming, including a more rational AH management, were assessed. The veterinarians recognize the need to consider the sustainability of the AH treatment but identify serval obstacles as the development of advices and the availability of simple, reliable and cheap tools.The results of this thesis show that it is possible to target the use of AH in FGSC basing on individual and group indicators.