RESUMO
The objectives of this experiment were to evaluate the effects of supplementation of Nellore (Bos indicus) cows with ß-carotene + vitamins A + D3 + E + biotin on body condition score (BCS), oestrus, pregnancy, and foetal morphometry. Lactating cows (n = 497) from two herds were balanced for BCS and calving period [early calving (EC); late calving (LC)] and were assigned randomly to: Control (n = 251)-supplementation with a mineral supplement; and SUP (n = 246)-supplementation with the mineral supplement fed to control + ß-carotene (150 mg/day) + vitamin A (40,000 IU/day) + vitamin D3 (5000 IU/day) + vitamin E (300 mg/day) + biotin (20 mg/day). Cows were supplemented from Days -30 to 30 (Day 0 = timed artificial insemination; TAI). Pregnancy was diagnosed 30 days after TAI and foetal crown-rump distance and thoracic diameter were measured at 30 and 77 days of gestation. Cows in the SUP treatment were more likely to have BCS ≥3.0 on Day 0 (63.0 ± 3.1 vs. 60.2 ± 3.1; p < .01) and were more likely to gain BCS from Days -30 to 30 (57.7 ± 3.3 vs. 44.1 ± 3.3%; p < .01). Fewer LC cows in the SUP treatment were detected in oestrus at the time of the first TAI (Control: LC: 75.4 ± 4.4 vs. SUP: LC: 64.0 ± 5.2 vs. Control: EC: 65.3 ± 4.0 vs. SUP: EC: 71.8 ± 3.7; p = .04). There was a tendency for the SUP treatment to increase pregnancy to the first TAI (64.2 ± 3.0 vs. 56.6 ± 3.1%; p = .08). A greater percentage of SUP cows was detected in oestrus at the time of the second TAI (70.1 ± 5.0 vs. 52.3 ± 4.8%; p = .01). The SUP treatment increased pregnancy to the second TAI among LC cows (SUP: LC: 75.9 ± 8.0% vs. Control: LC: 50.0 ± 8.3% vs. Control: EC: 52.0 ± 5.9% vs. SUP: EC: 41.4 ± 6.5%; p = .02). The SUP treatment increased foetal size (crown-rump; p = .04 and thoracic diameter; p < .01) at 30 days of gestation and, despite decreasing crow-rump length at 77 days after the first TAI among EC cows (p < .01), it increased the thoracic diameter at 77 days after the first TAI independent of calving season. Our results support that pregnancy establishment and foetal growth can be improved when grazing Nellore cows are supplemented with ß-carotene and vitamins A + D3 + E + biotin.
Assuntos
Biotina , Suplementos Nutricionais , Estro , Vitamina A , Vitamina E , beta Caroteno , Animais , Bovinos , Feminino , Gravidez , Vitamina A/administração & dosagem , Vitamina A/farmacologia , beta Caroteno/administração & dosagem , beta Caroteno/farmacologia , Vitamina E/administração & dosagem , Vitamina E/farmacologia , Estro/efeitos dos fármacos , Biotina/administração & dosagem , Biotina/farmacologia , Colecalciferol/farmacologia , Colecalciferol/administração & dosagem , Folículo Ovariano/efeitos dos fármacos , Dieta/veterinária , Vitaminas/administração & dosagem , Vitaminas/farmacologia , Ração Animal , Lactação , Feto/efeitos dos fármacosRESUMO
This study aimed to evaluate the effects of different doses of equine chorionic gonadotropin (eCG; 200 and 300 IU) administered at the end of a fixed-time artificial insemination (FTAI) treatment protocol on ovulation, pregnancy, and twin rates in Bos taurus beef heifers. In addition, pregnancy losses in heifers with singleton and twin pregnancies were determined. A total of 2382 Angus heifers treated with a 6-day estradiol/progesterone-based protocol for FTAI (J-Synch protocol) were randomly allocated to two experimental groups to receive 200 or 300 IU of eCG administered intramuscularly at the time of intravaginal progesterone device removal; FTAI was performed from 60 to 72 h after device removal. The pregnancy rate did not differ (P = 0.89) between the 200 and 300 IU eCG groups. The number of corpus luteum induced by both eCG doses was determined by ultrasonographic examination 14 days after insemination and those treated with 300 IU of eCG had a greater double ovulation rate (P < 0.05). In addition, 300 IU eCG treated heifers had a higher twinning rate on day 30 of gestation (P < 0.05) and parturition (P < 0.05). Pregnancy losses from 30 days of gestation to calving did not differ between heifers treated with 200 and 300 IU of eCG (P = 0.70). However, regardless of the experimental group, heifers bearing twins had greater pregnancy losses than heifers with singletons (P < 0.05). In conclusion, reducing the dose of eCG from 300 to 200 IU under FTAI treatment protocol decreases double ovulation and twinning rates, maintaining a similar pregnancy rate in heifers. Nulliparous cows carrying two fetuses suffer greater pregnancy losses than cows with singletons.
Assuntos
Gonadotropinas Equinas , Inseminação Artificial , Ovulação , Animais , Feminino , Gravidez , Bovinos/fisiologia , Inseminação Artificial/veterinária , Ovulação/efeitos dos fármacos , Gonadotropinas Equinas/farmacologia , Gonadotropinas Equinas/administração & dosagem , Gonadotropina Coriônica/farmacologia , Gonadotropina Coriônica/administração & dosagem , Aborto Animal , Gravidez de Gêmeos , Progesterona/administração & dosagem , Progesterona/farmacologia , Taxa de GravidezRESUMO
The efficiency of combining oestrous induction via a light program (16 h of light and 8 h of darkness for 60 days, ending on Day 0 - D0) with cloprostenol administration, followed by the male effect or not, was tested in acyclic Saanen goats during the non-breeding season (June/2019 to January/2020). Initially, all animals (males and females) were submitted to the described light program; 60 days after its ending (D60), the females were divided into two groups, with (G1; n = 67) or without (G2; n = 61) a male effect from D60 to D75 after the light program. At D75, both groups received two cloprostenol doses (120 µg; intramuscular) 7.5 days apart (D75 and D82.5). Artificial insemination was performed at a specific time according to the oestrous onset (approximately 68.4 ± 1.2 h between the second cloprostenol dose and IA). Ultrasound scans were performed at different intervals to evaluate follicular dynamics and confirm pregnancy. At the first cloprostenol dose (D75), the proportion of does with at least a corpus luteum (CL), which indicates resumed cyclicity, was greater in G1 than in G2 (85.2% vs. 48.8%; p < .05), although no difference was found at the second dose (p > .05). The adjusted pregnancy rates (number of pregnant goats/oestrous goats) differed between G1 and G2 (21.7% vs. 42.0%; p < .05). G1 also showed a higher frequency of functional CL (based on blood flow and morphology) compared to G2 (96.9% vs. 66.7%; p < .05) at D116. A male effect using photo-stimulated bucks after the first cloprostenol dose increased the number of does presenting CL after buck removal, and no impairment in the pregnancy rates of multiparous does was found.
Assuntos
Cloprostenol , Sincronização do Estro , Cabras , Inseminação Artificial , Estações do Ano , Animais , Cabras/fisiologia , Feminino , Masculino , Cloprostenol/farmacologia , Cloprostenol/administração & dosagem , Gravidez , Inseminação Artificial/veterinária , Prostaglandinas , Fotoperíodo , Reprodução/fisiologia , Reprodução/efeitos dos fármacosRESUMO
We aimed to evaluate the effects of administering estradiol (E-17ß) at the moment of timed-AI (TAI) on uterine gene expression, estrous expression rate (EER), and pregnancy rate (P/TAI) in Nelore cows with a small dominant follicle (DF) or not showing estrus at TAI. In Experiments 1 and 2 (Exp1, Exp2) cows were submitted to a P4/E-17ß-based protocol (day 0) for synchronization of ovulation. On day 7, devices were removed, cows received 1 mg E-17ß cypionate and 12.5 mg dinoprost. On day 9, cows with DF < 11.5 mm in diameter were split into different groups. In Exp1 (n = 16/group): Control (no treatment), E-2 (2 mg E-17ß) and E-4 (4 mg E-17ß). In Exp2: Control (n = 12); E-2 (n = 14); GnRH (0.1 mg gonadorelin acetate, n = 13); and E-2+GnRH (association of GnRH and E-17ß, n = 13). Between days 9 and 11, endometrial thickness (ET), time of ovulation detection, and EER were recorded. In Exp1, a uterine cytological sample was collected 4 h after treatment to evaluate the transcript expression of receptors for E-17ß (ESR1 and ESR2), oxytocin (OXTR), and P4 (PGR). In Experiment 3 (Exp3), 3829 suckled cows were submitted to a P4/E-17ß-based protocol for TAI. On day 9, devices were removed and cows received 1 mg E-17ß cypionate and 0.4 mg sodium cloprostenol. On day 11, TAI was performed and cows that did not demonstrate estrus received 0.1 mg gonadorelin acetate, and were allocated into two groups: GnRH (n = 368) and E-2+GnRH (2 mg E-17ß; n = 363). In Exp1, plasma E-17ß concentrations increased at 4 h after treatment in a dose-dependent manner but reduced at 12 h. The E-17ß-treated cows had greater transcript abundance for OXTR and lesser for ESR1 and ESR2, and the ET was reduced 12 h after treatment (P < 0.05). No significant difference (P > 0.1) was observed between the E-17ß doses in estrus or ovulation rate. In Exp2, the interval from treatment to ovulation was longer (P < 0.05) in the E-17ß group. GnRH-treated cows showed higher ovulation rates (89 vs. 35 %) compared to cows not treated with GnRH, as E-17ß-treated cows (P < 0.01) had a lower ovulation rate compared to those not receiving E-17ß (44 vs. 78 %). In Exp3, P/TAI was 55 % for cows in estrus. For those not showing estrus, no difference (P > 0.1) in P/TAI was observed between GnRH (34 %) and E-2+GnRH (31 %) groups. Cows with a DF ≥ 11 mm (n = 192) had a greater (P < 0.05) P/TAI (49 %) than those with DF < 11 mm (n = 377; 29 %). In conclusion, E-17ß administration in the moment of TAI modulates the mRNA expression of uterine receptors in cows with a small DF but does not impact the P/TAI compared with GnRH treatment in suckled Nelore not showing estrus previous to TAI.
Assuntos
Estradiol , Inseminação Artificial , Folículo Ovariano , Animais , Bovinos/fisiologia , Feminino , Estradiol/farmacologia , Estradiol/administração & dosagem , Estradiol/análogos & derivados , Gravidez , Inseminação Artificial/veterinária , Folículo Ovariano/efeitos dos fármacos , Sincronização do Estro/métodos , Sincronização do Estro/efeitos dos fármacos , Estro/efeitos dos fármacos , Útero/efeitos dos fármacos , Taxa de GravidezRESUMO
The impact of GnRH treatment on the day of TAI in beef cows has received limited investigation, especially concerning its association with estrus expression. Consequently, two experiments were conducted to assess the potential of GnRH treatment on the day of TAI to enhance fertility according to the expression or not of estrus in beef cows. Experiment 1 aimed to determine ovulation rate and luteal function, while Experiment 2 aimed to determine the effect of the two GnRH treatment approaches on pregnancy rate. In Experiment 1, multiparous Brangus suckling cows (n = 17) were submitted to an 8-day TAI protocol. Estrus occurrence was evaluated based on chalk removal on D10 (TAI) and cows were assigned to receive GnRH (25µg lecirelin; im) according to the group: GnRH (n = 7), regardless of estrus expression; or selectGnRH (n = 10), only cows not detected in estrus. Ovulation rate occurring until 77h after IVD removal did not differ (p = 0.17) between GnRH (85.7%; 6/7) and selectGnRH (100%; 10/10). Also, corpus luteum size and serum progesterone concentration were not affected (p>0.05) by treatments. In Experiment 2, crossbred taurine suckled cows (n = 384) were submitted to the same protocol as described in Experiment 1 and were randomly allocated to GnRH or selectGnRH groups. There was no difference in P/AI between groups (selectGnRH = 55.6%; GnRH = 54.3%; p = 0.7) 30 days after TAI. As expected, there was a pronounced effect (p<0.0001) of estrus expression on P/AI (Estrus = 61.5%; No estrus = 33.0%), regardless of group. In summary, ovulation timing and rate and luteal function did not differ between groups. Also, GnRH administration only in cows that do not show estrus is recommended, considering hormone savings and similar conception rate.
RESUMO
This study evaluated the efficacy of the administration of different doses of equine chorionic gonadotropin (eCG; 0 IU, 200 IU, or 300 IU) at the time of the progesterone device removal in 2-year-old Nelore (Bos indicus) heifers synchronized for fixed-timed artificial insemination (FTAI). On day 0 (D0), a total of 398 heifers received 2 mg of oestradiol benzoate i.m., 0.53 mg of cloprostenol i.m., and an eight-day previously used (second use) intravaginal device containing 1 g of progesterone (P4). Eight days later (D8), simultaneous with the P4 device removal, 0.5 mg of oestradiol cypionate i.m. and 0.53 mg of cloprostenol i.m. were administered. At the same time, heifers were randomly assigned to receive one of the following treatments: G-0 IU (n = 141; no eCG treatment), G-200 IU (n = 132; treated with 200 IU of eCG), and G-300 IU (n = 125; treated with 300 IU of eCG). FTAI was performed 48 h after the P4 device removal (D10). Ultrasonographic evaluations were performed at D0, D10, and D17. Heifers were scanned to measure the size of the largest follicle (LF), the presence, number, and size of the corpus luteum (CL), and the ovulation rate. Subsequently, at D40, the heifers underwent scanning to determine the pregnancy rate and identify any twin pregnancies. Additionally, at D70, scans were performed to assess pregnancy loss (PG). Data were analysed by orthogonal contrasts [C1 (eCG effect): control x (200 IU + 300 IU) and C2 (eCG dose effect): 200 IU × 300 IU]. On D0, CL presence was similar between the groups [G-0 IU = 65.2% (92/141), G-200 IU = 55.3% (73/132), and G-300 IU = 63.2% (79/125); p = .16]. No interactions between the presence of CL on D0 and eCG treatment were found for any of the variables (p > .05). The diameter of the LF at FTAI (D10) was not influenced by eCG treatment (p = .22) or eCG dose (p = .18). However, treatment with eCG increased the diameter of the CL at D17 (G-0 IU = 15.7 ± 0.3 mmb , G-200 IU = 16.6 ± 0.2 mma , and G-300 IU = 16.6 ± 0.3 mma ; p = .001), regardless of the dose used (p = .94). The ovulation rate was higher in heifers treated with eCG [G-0 IU = 79.4%b (112/141), G-200 IU = 90.2%a (119/132), and G-300 IU = 93.6%a (117/125); p = .002], but there was no effect of eCG dose (p = .36). Pregnancy per AI (P/AI) on D40 [G-0 IU = 32.6%b (46/141), G-200 IU = 42.4%a (56/132), and G-300 IU = 42.4%a (53/125); P = 0.05] and D70 [G-0 IU = 29.1%b (41/141), G-200 IU = 40.9%a (54/132), and G-300 IU = 40.8%a (51/125); p = .02] were higher on heifers that received eCG; however, no dose effect was observed for P/AI on D40 (p = .89) nor D70 (p = .98). Pregnancy loss between D40 and D70 tended to reduce (p = .07) in eCG-treated heifers without dose effect (p = .91). Heifers with CL at D0 presented a greater follicle diameter (LF) on D10 (With CL = 11.2 ± 0.2 mm and Without CL = 10.2 ± 0.2 mm; p = .05), CL diameter on D17 (With CL = 15.8 ± 0.03 mm and Without CL = 11.8 ± 0.6 mm; p = .01), and ovulation rate [With CL = 95.5% (233/244) and Without CL = 74.7% (115/154); p = .01]. However, no difference in pregnancy rate at D40 (p = .52) and D70 (p = .84) was found. In conclusion, eCG treatment increases ovulation and pregnancy rates of heifers submitted to a FTAI protocol. Furthermore, eCG treatment increases the diameter of the CL after FTAI and reduces pregnancy losses. No dose effect was observed, suggesting Nelore (Bos indicus) heifers respond to 200 IU of eCG treatment for FTAI.
Assuntos
Doenças dos Bovinos , Doenças dos Cavalos , Gravidez , Bovinos , Animais , Feminino , Cavalos , Progesterona/farmacologia , Aborto Animal , Ovulação , Estradiol/farmacologia , Cloprostenol/farmacologia , Inseminação Artificial/veterinária , Inseminação Artificial/métodos , Sincronização do Estro/métodosRESUMO
Three experiments were conducted to evaluate the effects of long-acting injectable progesterone (iP4) in buffalo cows. In Experiment 1, ovariectomized buffaloes received 300 mg (iP300) or 600 mg (iP600) of iP4, and serum P4 concentrations were evaluated. In experiment 2, three groups were compared: control or administration of 300 mg of iP4 3 (iP4-D3) or 6 days (iP4-D6) after timed artificial insemination (TAI). On day 16, reproductive tract was recovered for conceptus, endometrium, and corpus luteum (CL) analysis. In experiment 3, pregnancy per AI (P/TAI) and proportion of pregnancy losses were evaluated after administration of 300 mg of iP4 3 (iP4-D3) or 6 days (iP4-D6) after TAI in lactating buffaloes. In experiment 1, serum P4 concentrations remained over 1 ng/mL for ~ 3 days in both groups. The 300 mg dose was used in subsequent experiments. In experiment 2, CL weight and endometrial glands density were decreased, and conceptus length was increased in iP4-D3 compared to control and to iP4-D6 (P < 0.05). Transcript abundance of Prostaglandin F Receptor (FP) and ISG15 in CL and of ISG15 and MX1 in endometrium was greater in iP4-D3 when compared to control and to iP4-D6 (P < 0.05). In experiment 3, there was no difference among experimental groups for P/TAI at D30 and pregnancy losses (P > 0.1); however, iP4-D3 presented a lower P/TAI at day 60 (41.7%) when compared to control (56.8%) and iP4-D6 (57.7%; P = 0.07). In conclusion, administration iP4 at 3 days after TAI affects CL development and consequently decreases final pregnancy outcome in buffaloes.
Assuntos
Bison , Búfalos , Animais , Feminino , Bovinos , Gravidez , Progesterona , Lactação , Inseminação Artificial/veterinária , Luteína , Suplementos NutricionaisRESUMO
This summary addresses the use of reproduction technologies in swine farming, with an emphasis on artificial insemination (AI). Brazilian swine farming has been growing significantly and seeks new technologies to achieve high productive indices sustainably and competitively. Pigs present favorable characteristics such as high prolificacy, fertility, rapid growth, feed efficiency, and carcass yield, which has led to intensive development of the activity with advanced genetic selection. AI is widely employed to disseminate genetic material among different regions and farms. Several AI techniques are used in modern swine farming: intrauterine insemination (IUI) allows semen deposition in the uterine region, reducing costs; fixed-time insemination (FTAI) synchronizes estrus in various females, facilitating management and increasing efficiency; deep intrauterine insemination (DIUI) deposits semen in the uterine horns, obtaining better results; and cervical insemination (CI), a traditional technique widely used, although it may be more time-consuming and present higher reflux rates. The success of AI is related to knowledge of the reproductive cycle of sows, proper nutrition, and genetic and environmental factors. Semen quality is essential, requiring collection by trained professionals and evaluation of sperm motility and morphology. Although it is a consolidated technique, there are issues to be further explored to optimize its application, defining the exact moment for insemination, reducing reflux, and adopting effective protocols. AI is an essential tool for the growth of Brazilian swine farming, but it requires continuous studies to maximize its efficiency and results, considering the farm's production goal and the size of the enterprise to achieve high reproductive and productive indices.
Este resumo aborda o uso de tecnologias de reprodução na suinocultura, com ênfase na inseminação artificial (IA). A suinocultura brasileira vem crescendo significativamente e busca novas tecnologias para alcançar altos índices produtivos de maneira sustentável e competitiva. Os suínos apresentam características favoráveis, como alta prolificidade, fertilidade, rápido crescimento, eficiência alimentar e rendimento de carcaça, o que levou ao desenvolvimento intensivo da atividade com seleção genética avançada. A IA é amplamente empregada para disseminar material genético entre diferentes regiões e granjas. Diversas técnicas de IA são utilizadas na suinocultura moderna: a inseminação intrauterina (IAIU) permite a deposição do sêmen na região uterina, reduzindo custos; a inseminação em tempo fixo (IATF) sincroniza o estro em várias fêmeas, facilitando o manejo e aumentando a eficiência; a inseminação intrauterina profunda (IAUP) deposita o sêmen nos cornos uterinos, obtendo melhores resultados; e a inseminação cervical (IAC), técnica tradicional amplamente utilizada, embora possa ser mais demorada e apresentar maiores taxas de refluxo. O sucesso da IA estar relacionado ao conhecimento do ciclo reprodutivo das matrizes, à nutrição adequada e aos fatores genéticos e ambientais. A qualidade do sêmen é essencial, exigindo coleta por profissionais treinados e avaliação da motilidade e morfologia dos espermatozoides. Apesar de ser uma técnica consolidada, há questões a serem aprofundadas para otimizar sua aplicação, definindo o momento exato para a realização da inseminação, a redução do refluxo e adoção de protocolos eficazes. A IA é uma ferramenta essencial para o crescimento da suinocultura brasileira, mas requer estudos contínuos para maximizar sua eficiência e resultados, considerando o objetivo produtivo da granja e o tamanho do empreendimento para alcançar altos índices reprodutivos e produtivos.
Este resumen aborda el uso de tecnologías de reproducción en la producción porcina, con énfasis en la inseminación artificial (IA). La producción porcina brasileña ha crecido significativamente y busca nuevas tecnologías para alcanzar altos índices de productividad de manera sostenible y competitiva. Los cerdos presentan características favorables, como alta prolificidad, fertilidad, rápido crecimiento, eficiencia alimentaria y rendimiento de la canal, lo que ha llevado al desarrollo intensivo de la actividad con selección genética avanzada. La IA se utiliza ampliamente para difundir material genético entre diferentes regiones y granjas. Diversas técnicas de IA son utilizadas en la producción porcina moderna: la inseminación intrauterina (IAIU) permite la deposición del semen en la región uterina, reduciendo costos; la inseminación a tiempo fijo (IATF) sincroniza el estro en varias hembras, facilitando el manejo y aumentando la eficiencia; la inseminación intrauterina profunda (IAUP) deposita el semen en los cuernos uterinos, obteniendo mejores resultados; y la inseminación cervical (IAC), técnica tradicional ampliamente utilizada, aunque puede ser más demorada y presentar mayores tasas de reflujo. El éxito de la IA está relacionado con el conocimiento del ciclo reproductivo de las hembras, la nutrición adecuada y los factores genéticos y ambientales. La calidad del semen es esencial, requiriendo la recolección por profesionales capacitados y la evaluación de la motilidad y morfología de los espermatozoides. A pesar de ser una técnica consolidada, hay aspectos que deben ser profundizados para optimizar su aplicación, como la definición precisa del momento de la inseminación, la reducción del reflujo y la adopción de protocolos eficaces. La IA es una herramienta esencial para el crecimiento de la producción porcina brasileña, pero requiere estudios continuos para maximizar su eficiencia y resultados, considerando el objetivo productivo de la granja y el tamaño del emprendimiento para alcanzar altos índices reproductivos y productivos.
Assuntos
Animais , Motilidade dos Espermatozoides , Suínos/fisiologia , Inseminação Artificial/veterinária , Técnicas de Reprodução Assistida/veterinária , Análise do Sêmen/veterináriaRESUMO
Background: Most dairy cattle breeds originate show an average generational inbreeding rate of 1%, which favors the occurrence of recessive defects associated with low reproductive performance. Aim: The objective of this study was to monitor recessive defects associated with low reproductive performance in dairy cattle. Methods: To monitor bulls carrying the Holstein Friesian haplotype (HH) 1, HH3, and HH4 haplotypes, we analyzed the records of 3,028 national and imported Holstein Friesian bulls from the 2021 updated sires' catalog published by "Evaluaciones Genéticas Lecheras"; and to determine the presence of these mentioned haplotypes, as well as Jersey haplotype (JH) 1 and complex vertebral malformation (CVM), were genotype with the GeneTitan® 2,500 single nucleotide polymorphism (SNP) bovine chip, estimate their frequencies and evaluate their impact on the fertility of 100 Holstein Friesian cows and 70 Holstein Friesian-Jersey crosses belonging to an experimental dairy. Results: From a total of 1,468 (48.5%) bulls with genetic information from the sires' catalog for HH1 and 1,471 (48.6%) for HH3 and HH4, we found 90 (6.1%) carriers for HH1, 60 (4.1%) for HH3, and 6 (0.4%) for HH4, respectively. By genotyping with the chip, we calculated the herd frequency of the mutant alleles and herd prevalence of carriers for HH1 and CVM as q = 0.003 and 0.022; 0.59% and 4.3% (call rate >0.99), respectively. No mutant alleles were found for HH3, HH4, and JH1 in the analyzed population. We examined reproductive data by observing the presence of CVM and HH1 mutant alleles in repeat cows with an average of four services to achieve pregnancy. Conclusion: This study demonstrated the presence of recessive defects associated with low reproductive performance in the analyzed population, which can affect the health and productivity of dairy cattle. Therefore, cows and bulls should be closely monitored through genetic testing to lower the incidence of recessive defects in dairy cattle.
Assuntos
Fertilidade , Gravidez , Feminino , Bovinos/genética , Animais , Masculino , Uruguai , Genótipo , Fertilidade/genética , HaplótiposRESUMO
This study aimed to evaluate the physiological and reproductive parameters of Nelore cows under various microclimatic conditions. The experiment was performed in Central Brazil, which has a tropical climate with dry winters and rainy summers. The experimental groups were divided into an area with shading (5.8 trees/ha; n = 42) and an area with little shading (0.4 trees/ha; n = 42). The physiological (heart rate, respiratory rate, rectal temperature, surface body temperature, and vaginal temperature) and reproductive (estrus detection, conception rate, and rate of pregnancy loss) parameters were then assessed. The rectal temperature (p = 0.002); surface body temperature on the flanks, forehead, and shoulder (p < 0.001); and vaginal temperature (p < 0.001) of cows in the group with shading were significantly lower than those of cows in the group without shading. Estrus was higher (p = 0.08) in the shaded group; however, no effect was observed on conception and pregnancy loss rates. In conclusion, shading (5.8 trees/ha) provided better thermal comfort for Nelore animals in the tropical climatic region. However, this did not affect their performance after fixed-time artificial insemination.