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This study aimed to establish the relationship between antral follicle count (AFC), the time of puberty, and ovarian response in Nelore heifers subjected to timed-AI (TAI) protocols. Prepubescent Nelore heifers (Bos indicus; n = 30) were examined by transrectal ultrasound and videos of the ovaries were recorded for later CFA (? 3 mm). After AFC, heifers were divided into 2 groups, low and high AFC and then further ultrasonic ovarian assessments were performed to determine the onset of puberty. Once puberty was established in all heifers, they were submitted to an FTAI protocol. There were no differences (P > 0.1) between groups on the time of puberty, ovulation rate, the proportion of heifers that expressed estrus, and on preovulatory follicle diameter. However, heifers with low AFC had a smaller ovarian area in the prepubertal period (4.36 ± 0.3 vs. 5.65 ± 0.2 cm2) and, in the FTAI, they had the moment of estrus (48 ± 0.0 vs. 58.5 ± 3.1 h) and earlier ovulation (60 ± 1.8 vs. 72.6 ± 4.7 h) compared to heifers with high AFC (P < 0.05). In addition, heifers in the low AFC group had a higher (P = 0.05) pregnancy per AI (76.9%, 10/13) than the high AFC group (29.4%, 5/17). In this study, heifers with low AFC had the moment of ovulation anticipated and greater pregnancy per AI compared to heifers with high AFC. O objetivo deste estudo foi estabelecer a relação entre contagem de folículos antrais (CFA), idade à puberdade e resposta ovariana em novilhas Nelore submetidas a protocolos de Inseminação Artificial em Tempo Fixo (IATF). Novilhas Nelore pré-púberes (Bos indicus; n = 30) foram avaliadas por ultrassonografia transretal e vídeos dos ovários foram gravados para posterior CFA. Após a CFA, as novilhas foram divididas em 2 grupos, CFA baixa e alta e então avaliações ultrassonográficas dos ovários foram realizadas para determinar a puberdade. Uma vez estabelecida a puberdade em todas as novilhas, elas foram submetidas a protocolo de IATF. Não houve diferenças (P > 0,1) entre os grupos na idade à puberdade, na taxa de ovulação, na proporção de novilhas que expressaram estro e no diâmetro do folículo pré-ovulatório. No entanto, novilhas com baixa CFA apresentaram menor área ovariana no período prépúbere (4,36 ± 0,3 vs. 5,65 ± 0,2 cm2) e, na IATF, tiveram o momento do estro (48 ± 0,0 x 58,5 ± 3,1 h) e ovulação antecipados (60 ± 1,8 vs. 72,6 ± 4,7 h) em comparação com novilhas com alta CFA (P < 0,05). Além disso, as novilhas do grupo de baixa CFA apresentaram maior (P = 0,05) prenhez por IA (76,9%, 10/13) que o grupo de alta CFA (29,4%, 5/17). Nesse estudo, novilhas com baixa CFA tiveram o momento da ovulação antecipado e maior prenhez por IA em comparação com novilhas com alta CFA. El objetivo de este estudio fue establecer la relación entre el conteo de folículos antrales (AFC), el tiempo de pubertad y la respuesta ovárica en novillas Nelore sometidas a protocolos inseminación artificial a tiempo fijo (TAI). Novillas Nelore prepubescentes (Bos indicus; n = 30) fueron examinadas mediante ultrasonido transrectal y se grabaron videos de los ovarios para posterior CFA (? 3 mm). Después de AFC, las vaquillas se dividieron en 2 grupos, AFC bajo y entonces se realizaron evaluaciones de ovario para determinar el inicio de la pubertad. Una vez establecida la pubertad, las vaquillas fueron sometidas a un protocolo FTAI. No hubo diferencias (P > 0.1) entre los grupos en el momento de la pubertad, la tasa de ovulación, la proporción de vaquillas que expresaron celo y el diámetro del folículo preovulatorio. Sin embargo, las vaquillas con AFC bajo tuvieron menor área ovárica en el período prepuberal (4,36 ± 0,3 x 5,65 ± 0,2 cm2) y, en el IATF, tuvieron el momento del estro (48 ± 0,0 x 58,5 ± 3,1 h) y ovulación más temprana (60 ± 1,8 x 72,6 ± 4,7 h) en comparación con novillas con AFC alto (P < 0,05). Además, las vaquillas en el grupo de AFC bajo tuvieron una tasa de preñez más alta (P = 0.05) (76.9 %, 10/13) que el grupo de AFC alto (29.4 %, 5/17). Las vaquillas con AFC bajo tuvieron el momento de ovulación anticipado y mayor preñez por IA en comparación con las vaquillas con AFC alto. Made available in DSpace on 2022-06-02T17:19:41Z (GMT). No. of bitstreams: 1 cpafro-18763.pdf: 119509 bytes, checksum: 4a1721a3d036b32110f6ffd5843c632d (MD5) Previous issue date: 2022

Two experiments evaluated the effects of gonadotropin releasing hormone (GnRH) treatment on fertility of suckled Nelore beef cows treated with an estradiol/progesterone (P4)-based protocol for timed artificial insemination (TAI). Experiment 1 was designed to determine the effect of GnRH administered 34 h after P4 insert removal (GnRH34) on time of ovulation. Suckled cows (n = 34) were treated with 2 mg estradiol benzoate (EB) and an intravaginal insert containing 1.9 g of P4. Eight days later, P4 inserts were removed, and all cows received 150 μg of d-cloprostenol (prostaglandin F2 alpha analogue), 300 IU of eCG, and 1 mg of estradiol cypionate (ECP). On Day 9 (05:00 p.m.), cows were randomly distributed, according to the diameter of the pre-ovulatory follicle, in two treatments: 1) GnRH (n = 17) cows that received 10.5 μg of buserelin acetate, or 2) no further treatment (control, n = 17). Cows treated with GnRH 34 h after P4 insert removal ovulated earlier (P = 0.02) than control cows (66 ± 0.0 and 77.2 ± 4.3 h). Experiment 2 was designed to determine the effect of GnRH34 on the fertility of suckled beef cows. Nelore cows (n = 506) were treated as Experiment 1. On Day 8, cows were painted in the sacrocaudal region to identify cows that displayed estrus. On Day 9 (05:00 p.m.), cows were randomized to receive same treatment as Experiment 1, control (n = 252), or GnRH (n = 254). All cows were TAI 48 h after P4 insert removal. At TAI, estrus was evaluated, and deemed to have occurred in cows without a tail-head chalk mark (75% paint loss). Cows treated with GnRH 34 h after P4 insert removal had greater (P = 0.01) pregnancy per AI (P/AI) than cows that only received ECP (63.0% and 50.4%). No difference (P = 0.5) was observed in the proportion of cows that displayed estrus between treatments. Furthermore, cows that displayed estrus had greater (P 0.01) P/AI than cows that did not. Treatment with GnRH, given at 34 h after P4 insert removal, increased (P 0.05) P/AI in cows that did not show estrus at TAI. In summary, treatment with GnRH 34 h after P4 insert removal was associated with earlier ovulation and resulted in greater P/AI in suckled Nelore cows treated with an estradiol/P4-based protocol for TAI.

A programação fetal, também chamada de programação do desenvolvimento, é conceito de um estímulo materno através da dieta sobre o desempenho e crescimento do feto, os quais estão relacionados aos efeitos do ambiente uterino através de mecanismos epigenéticos. Os mecanismos epigenéticos modulam a adaptação do feto ao ambiente uterino através do silenciamento ou ativação gênica. As forragens tropicais cultivadas no Brasil apresentam baixo valor nutricional, principalmente na estação seca do ano, e podem ser inadequadas para garantir a nutrição ideal para o crescimento, prenhez e lactação. Dessa forma, a suplementação proteica de vacas de corte no terço final da gestação torna-se importante, por ser uma fase em que ocorre o crescimento exponencial do feto com maior demanda nutricional. Tendo como objetivos alterar o eixo hipotálamo-hipófise-adrenal do feto por causar impressão metabólica ou endócrina, como também efeitos sobre as células musculares, permitindo a promoção potencial da miogênese e adipogênese do músculo fetal. O objetivo desta revisão é abordar os conceitos relacionados à programação fetal e os efeitos da suplementação proteica de vacas de corte no terço final da gestação sobre o desempenho produtivo e reprodutivo da progênie.

Several studies have shown that cows displaying estrus before timed artificial insemination (TAI) are more likely to become pregnant. However, the most frequently used ovulation-inducing agents by South American beef operations, estradiol esters, may artificially induce estrus in treated cows. The hypotheses tested in the present study were: 1) estradiol cypionate (EC) treatment will induce estrus in ovariectomized cows, and 2) cows that exhibit estrus following administration of EC and eCG will have lower P/AI compared to those that do not receive EC. In Experiment 1, 14 ovariectomized cows were used in a cross-over design with an interval of 30 d between replicates. On Day 0, all cows received 2 mg of estradiol benzoate and a CIDR device and 12.5 mg of Dinoprost (PGF2α analogue) on Day 7. On Day 9, the CIDR devices were removed and cows were placed at random into one of two experimental groups and administered either 0.5 mL of canola oil (Control, CTL group, n = 14) or 1 mg of EC (EC group, n = 14). Estrotect estrus detection patches were used and cows were observed 4 times daily to determine the occurrence of estrus. More EC-treated cows showed estrus (12/14, 85.7%) than canola oil-treated cows (0/14; P

Body condition score (BCS) is a categorical variable that is widely accepted as an important tool for subjectively quantifying energy reserves in dairy cows. The aims of this study was to compare milk production and some metabolic parameters of crossbred dairy cows with low, adequate and high BCS in the recent postpartum period (PPP). This study included lactation data from 35 crossbred Girolando (Holstein × Gir) cows from calving to 90 days in milk. Cows were evaluated every 15 days for BCS, milk production, live weight, internal angle of the rump (IAR) and serum concentration of β-hydroxybutyrate (ßHB). BCS loss and nadir of the BCS in PPP were also evaluated. Cows were divided into 3 groups, as follows: High, Adequate and Low BCS, according to the BCS recommendation for cows with less than 100 days in lactation. Cows with Adequate BCS had higher milk production than cows with High BCS (P = 0.01). Cows with High BCS had the highest (P < 0.001) live weight, BCS and IAR among the groups. In addition, these cows had a higher serum ßHB concentration than cows with Adequate BCS (P = 0.001) and had the greatest loss of BCS (P < 0.001) in the PPP. The results of this study showed that Girolando dairy cows with Adequate BCS at calving had higher milk production and better metabolic condition than cows with High BCS at calving. La condición corporal (CC) es una variable categórica ampliamente aceptada como una herramienta importante para cuantificar subjetivamente las reservas de energía en las vacas lecheras. El objetivo de este estudio fue comparar la producción de leche y algunos parámetros metabólicos de vacas lecheras mestizas con CC baja, adecuada y alta en el posparto reciente (PP). Este estudio incluyó datos de lactancia de 35 vacas Girolando (Holstein × Gir) desde el parto hasta los 90 días de lactancia. Las vacas fueron evaluadas cada 15 días para CC, producción de leche, peso vivo, ángulo interno de la grupa (AIG) y concentración sérica de β-hidroxibutirato (ßHB). También se evaluaron la pérdida de CC y el nadir de CC en PP. Las vacas se dividieron en 3 grupos, CC Alta, Adecuada y Baja, de acuerdo con la recomendación de CC para vacas con menos de 100 días de lactancia. Las vacas con CC adecuado tuvieron mayor producción de leche que las vacas con CC alto (P = 0,01). Las vacas con alto CC tuvieron el peso vivo, CC y AGA más altos (P < 0,001) entre los grupos. Además, estas vacas tenían una concentración sérica de ßHB más alta que las vacas con CC Adecuado (P = 0,001) y tenían la mayor pérdida de CC (P < 0,001). Los resultados de este estudio mostraron que las vacas Girolando con CC adecuado al parto tuvieron una mayor producción de leche y una mejor condición metabólica en comparación con las vacas con CC alto al parto. O escore de condição corporal (ECC) é uma variável categórica amplamente aceita como uma importante ferramenta para quantificar subjetivamente as reservas energéticas em vacas leiteiras. O objetivo deste estudo foi comparar a produção de leite e alguns parâmetros metabólicos de vacas leiteiras mestiças com baixo, adequado e alto ECC no período pós-parto (PPP) recente. Este estudo incluiu dados de lactação de 35 vacas mestiças Girolando (Holandês × Gir) do parto aos 90 dias de lactação. As vacas foram avaliadas a cada 15 dias quanto ao ECC, a produção de leite, o peso vivo, o ângulo interno da garupa (AIG) e a concentração sérica de β-hidroxibutirato (ßHB). Também foram avaliados a perda de ECC e o nadir do ECC no PPP. As vacas foram divididas em 3 grupos, Alto, Adequado e Baixo ECC, de acordo com a recomendação de ECC para vacas com menos de 100 dias em lactação. Vacas com ECC adequado apresentaram maior produção de leite que vacas com ECC alto (P = 0,01). Vacas com alto ECC apresentaram o maior (P < 0,001) peso vivo, ECC e o AIG entre os grupos. Além disso, essas vacas apresentaram maior concentração sérica de ßHB do que vacas com ECC Adequado (P = 0,001) e apresentaram a maior perda de ECC (P < 0,001). Os resultados deste estudo demonstraram que vacas Girolando com ECC adequado ao parto apresentaram maior produção de leite e melhor condição metabólica em relação às vacas com alto ECC ao parto.

The aim of this study was to evaluate the uterine health and fertility of postpartum beef cows subjected to timed AI (TAI) protocols at different days from calving. Lactating Nelore cows (Bos indicus; n = 244) were used in this study. The TAI protocols were initiated between 20 and 60 days postpartum (DPP). Cows were subjected to an estradiol-progesterone based TAI protocol. The cows were divided into three groups according to the days postpartum at the time the hormonal treatment was initiated: 1) Early (n = 64), cows between 20 and 30 DPP; 2) Middle (n = 115), cows between 31 and 45 DPP; and 3) Late (n = 65), cows between 46 and 60 DPP. At Day 0 of the protocol, endometrial cytobrush samples were collected. Slides for polymorphonuclear (PMN) cell counting were prepared and cytobrush was used for RNA extraction and analysis of relative abundance of il1, il6, il8, and tnf mRNA. Cows from the Early group had less (P < 0.05) pregnancies per AI (P/AI) than cows from Middle and Late groups; 29.7% (19/64), 45.2% (52/115), and 52.31% (34/65), respectively. Accordingly, the Early group had a greater (P < 0.05) proportion of PMN cells in the uterus than Middle and Late groups; 9.0%, 3.8%, and 2.2%, respectively. Relative abundances of il1 and il8 mRNA were greater (P < 0.05) in the Early group than Middle and Late groups. These results indicate that beef cows subjected to TAI protocols early postpartum (< 30 DPP) are less likely to become pregnant, which is associated with increased inflammation and relative abundance of mRNA for the proinflammatory cytokines il1 and il8. Made available in DSpace on 2018-09-19T00:37:45Z (GMT). No. of bitstreams: 1 ARSsaudeuterina2018.pdf: 594443 bytes, checksum: 9d8ba15673f05ae291d440664e2fb4f4 (MD5) Previous issue date: 2018-09-18

This study evaluated the effect of uterine health on the fertility of postpartum beef cows. Multiparous lactating Nelore cows (Bos indicus; n = 155) were subjected to a timed artificial insemination (TAI) protocol. Cows were included in a progesterone-estradiol based TAI protocol. On Day 0, before the beginning of the protocol, cows were subjected to evaluation of purulent vaginal discharge (PVD) and collection of uterine tissue using the cytobrush technique. Slides for polymorphonuclear (PMN) cells counting were prepared before the same cytobrush was used for RNA extraction and analysis of IL-1β, IL-6, IL-8, TNFα, GAPDH, and βactin gene transcription. Cows were separated into 4 categories according to the proportion of PMN and PVD: 1) Healthy (HE; n = 87), cows with ≤ 4.75% PMN and PVD of 0; 2) Positive Purulent Vaginal Discharge (PVD+; n = 24), cows with ≤ 4.75% PMN and PVD ≥ 1; 3) Subclinical Endometritis (SCE; n = 29), cows with > 4.75% PMN and PVD of 0, and; 4) Subclinical Endometritis + PVD+ (SCEP; n = 15), cows with > 4.75% PMN and PVD ≥ 1. Cows in the HE group had a greater (P 0.05). Cows from the SCE and SCEP groups had a higher (P 0.05). In contrast, transcription of IL-8 was greater (P = 0.02) in SCEP than HE and SCE groups. The relative transcription IL-1β was greater (P

The aims of this study were to determine (1) the association between Doppler vascularisation scores (DVS) of the preovulatory follicle (POF) and fertility of beef cows submitted to timed AI (TAI) and (2) whether cows with low DVS benefit from a gonadotrophin-releasing hormone (GnRH) treatment at TAI. Multiparous lactating Nelore cows (Bos indicus; n=69) from a commercial beef farm in the state of Rondônia, Brazil, were enrolled in this study. Cows received 2mg of oestradiol benzoate intramuscularly (Bioestrogen, Biogénesis Bagó) and an intravaginal progesterone-releasing device (1.9g of progesterone; controlled internal drug release, CIDR) to synchronise follicular wave emergence on Day 0. The CIDR device was removed and cows were treated with 150μg of D-cloprostenol intramuscularly (prostaglandin F2α analogue; Croniben), 1mg of oestradiol cypionate intramuscularly, and 300IU of equine chorionic gonadotrophin (Novormon) intramuscularly on Day 8. Cows were then painted with a tail chalk marker to identify those displaying oestrus. All cows were submitted to TAI 48h after CIDR removal. At TAI, occurrence of oestrus was recorded and all cows were examined using transrectal ultrasonography. Blood flow of the POF was evaluated using colour Doppler imaging. Colour Doppler signals present on the follicular wall were subjectively scored using a 1-to-4 scale (1=absence or very low blood flow, and 4=intense blood flow detected on most of the follicular wall surface) adapted from Ginther (2007Ultrasonic Imaging and Animal Reproduction: Color-Doppler Ultrasonography, pages 87-114). Then, cows were divided into three groups according their DVS of the POF: (1) high DVS (DVS ≥3; n=36), (2) low DVS (DVS

Body condition score (BCS) is a categorical variable that is widely accepted as an important tool for subjectively quantifying energy reserves in dairy cows. The aims of this study was to compare milk production and some metabolic parameters of crossbred dairy cows with low, adequate and high BCS in the recent postpartum period (PPP). This study included lactation data from 35 crossbred Girolando (Holstein × Gir) cows from calving to 90 days in milk. Cows were evaluated every 15 days for BCS, milk production, live weight, internal angle of the rump (IAR) and serum concentration of ?-hydroxybutyrate (ßHB). BCS loss and nadir of the BCS in PPP were also evaluated. Cows were divided into 3 groups, as follows: High, Adequate and Low BCS, according to the BCS recommendation for cows with less than 100 days in lactation. Cows with Adequate BCS had higher milk production than cows with High BCS (P = 0.01). Cows with High BCS had the highest (P < 0.001) live weight, BCS and IAR among the groups. In addition, these cows had a higher serum ßHB concentration than cows with Adequate BCS (P = 0.001) and had the greatest loss of BCS (P < 0.001) in the PPP. The results of this study showed that Girolando dairy cows with Adequate BCS at calving had higher milk production and better metabolic condition than cows with High BCS at calving. O escore de condição corporal (ECC) é uma variável categórica amplamente aceita como uma importante ferramenta para quantificar subjetivamente as reservas energéticas em vacas leiteiras. O objetivo deste estudo foi comparar a produção de leite e alguns parâmetros metabólicos de vacas leiteiras mestiças com baixo, adequado e alto ECC no período pós-parto (PPP) recente. Este estudo incluiu dados de lactação de 35 vacas mestiças Girolando (Holandês × Gir) do parto aos 90 dias de lactação. As vacas foram avaliadas a cada 15 dias quanto ao ECC, a produção de leite, o peso vivo, o ângulo interno da garupa (AIG) e a concentração sérica de ?-hidroxibutirato (ßHB). Também foram avaliados a perda de ECC e o nadir do ECC no PPP. As vacas foram divididas em 3 grupos, Alto, Adequado e Baixo ECC, de acordo com a recomendação de ECC para vacas com menos de 100 dias em lactação. Vacas com ECC adequado apresentaram maior produção de leite que vacas com ECC alto (P = 0,01). Vacas com alto ECC apresentaram o maior (P < 0,001) peso vivo, ECC e o AIG entre os grupos. Além disso, essas vacas apresentaram maior concentração sérica de ßHB do que vacas com ECC Adequado (P = 0,001) e apresentaram a maior perda de ECC (P < 0,001). Os resultados deste estudo demonstraram que vacas Girolando com ECC adequado ao parto apresentaram maior produção de leite e melhor condição metabólica em relação às vacas com alto ECC ao parto. La condición corporal (CC) es una variable categórica ampliamente aceptada como una herramienta importante para cuantificar subjetivamente las reservas de energía en las vacas lecheras. El objetivo de este estudio fue comparar la producción de leche y algunos parámetros metabólicos de vacas lecheras mestizas con CC baja, adecuada y alta en el posparto reciente (PP). Este estudio incluyó datos de lactancia de 35 vacas Girolando (Holstein × Gir) desde el parto hasta los 90 días de lactancia. Las vacas fueron evaluadas cada 15 días para CC, producción de leche, peso vivo, ángulo interno de la grupa (AIG) y concentración sérica de ?-hidroxibutirato (ßHB). También se evaluaron la pérdida de CC y el nadir de CC en PP. Las vacas se dividieron en 3 grupos, CC Alta, Adecuada y Baja, de acuerdo con la recomendación de CC para vacas con menos de 100 días de lactancia. Las vacas con CC adecuado tuvieron mayor producción de leche que las vacas con CC alto (P = 0,01). Las vacas con alto CC tuvieron el peso vivo, CC y AGA más altos (P < 0,001) entre los grupos. Además, estas vacas tenían una concentración sérica de ßHB más alta que las vacas con CC Adecuado (P = 0,001) y tenían la mayor pérdida de CC (P < 0,001). Los resultados de este estudio mostraron que las vacas Girolando con CC adecuado al parto tuvieron una mayor producción de leche y una mejor condición metabólica en comparación con las vacas con CC alto al parto. Made available in DSpace on 2022-06-02T18:19:24Z (GMT). No. of bitstreams: 1 cpafro-18764.pdf: 154137 bytes, checksum: a7d1e21b8ac29643a47a4d85ba61f440 (MD5) Previous issue date: 2022