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Cervical relaxation (CR) was performed in ewes during diestrus, to prospect a feasible protocol for non-surgical embryo transfer (NSET). In Trial 1, naturally mated ewes (n=13) received CR protocols with estradiol benzoate (EB, 1 mg on D6) and oxytocin (OT, 50 IU on D7) only (G-EB+OT) or associated with human chorionic gonadotropin (hCG, 300 IU on D7, G-EB+OT+hCG) and were compared to non-hormonally treated (G-control) ewes. Estradiol concentration increased (P<0.05) from D6 to D7 in G-EB+OT and G-EB+OT+hCG, then decreased (P<0.05) on D8. The G-EB+OT had reduced (P<0.05) progesterone on D8, and 0% (0/5) pregnancy, while G-control had 100% (3/3) conception rate. The treatment with hCG mitigated the progesterone drop on D8 and resulted in 50% (2/4) conception rate. In Trial 2, cervical transposing success after treatment with EB, OT, and hCG on D6 and D7 was assessed in nulliparous (n=25) and multiparous (n=30) ewes. The EB+OT+hCG protocol allowed efficient cervical transposition (~78% of cervical transposition success into ~5 min) in nulliparous and multiparous females and did not alter total and blood perfusion areas of corpora lutea (CL). The use of EB+OT+hCG was efficient to ensure effective cervical transposing in nulliparous and multiparous ewes, with no apparent deleterious effect on CL function, and may contribute to animal welfare, allowing a less invasive NSET procedure. [ABSTRACT FROM AUTHOR]

Simple Summary: Understanding the principles of beef cattle behavior and their attitudes, whether as a result of the learning process or as a response to environmental stimuli, is important for providing greater sensitivity and efficiency to modern production systems. Our study evaluated the behavior of young zebu (Nelore) and composite (Canchim) bulls kept in pasture production systems, either in a crop–livestock–forest integration (ICLF) or without afforestation. The behavior of animals was assessed electronically and by direct observation. The results revealed that the breed and production system influenced the expression of the animals' daily activities. The ICLF system had a milder microclimate and favored thermal comfort. Natural shading influenced grazing, resting, and rumination time, but did not interfere with cortisol concentration. Grazing and rumination times were longer for Canchim than Nelore bulls, while Nelore bulls spent more time resting, either standing or lying. The breed had no impact on the frequency of water and mineral mixture intake. This investigation sheds light on the differences in animal behavior depending on their breed and the configuration of production systems, which vary with the availability of natural shade. This knowledge can help producers make decisions, ensuring greater animal welfare, better working conditions, and greater management efficiency. The behavior of ruminants can influence their productive efficiency. The aim of this study was to evaluate the behavior of young zebu and composite bulls kept in pasture production systems, either in a crop-livestock-forest integration or without afforestation. The work was carried out in São Carlos, Brazil (21°57′42″ S, 47°50′28″ W), in a high-altitude tropical climate, from March to July, 2022. Forty young bulls were evaluated, being 20 Nelore (Bos indicus) (342.5 ± 36.6 kg BW; 16.9 ± 1.8 months) and 20 Canchim (5/8 Bos taurus × 3/8 Bos indicus) (338.4 ± 39.8 kg BW; 19.1 ± 1.9 months), equally distributed in full-sun (FS) and integrated crop–livestock–forestry (ICLF) production systems. Behavior was monitored uninterruptedly by an acoustic sensor and accelerometer attached to a collar, and complemented by direct visual assessment, in two one-day campaigns per month. Serum cortisol concentration was assessed monthly. Statistical analyses were conducted using a general linear model at a 5% significance level (SAS, version 9.4). The ICLF system had a milder microclimate and favored thermal comfort. Natural shading influenced grazing, resting, and rumination time. The Canchim bulls were more active when moving and grazing (p < 0.05), even at the hottest times of the day. In turn, the Nelore bulls spent more time resting at all times (p < 0.001), which was shown to be an adaptive strategy in response to environmental stimuli. The Canchim bulls had a longer rumination time than the Nelore bulls (p < 0.001), due to their longer grazing time. The frequency of water and mineral mixture intake did not differ between genotypes, regardless of the production system (p > 0.05). There was no difference in the serum cortisol concentrations of the Nelore and Canchim bulls kept in FS or ICLF (p = 0.082). Thus, young bulls of the different genotypes showed different behaviors, regardless of whether they were kept on pasture without afforestation or in an integrated crop–livestock–forestry system. [ABSTRACT FROM AUTHOR]

Simple Summary: The objective was to characterize the pastures by grazing cycle, as well as to evaluate the performance of buffaloes in intensive rotational grazing in a silvopastoral system in the eastern Amazon supplemented with agro-industry co-products in order to characterize the grazing cycles, the composition of the fractions and the carcass yield. Fifteen non-castrated, crossbred water buffaloes (Murrah × Mediterranean) were used. Forage protein varied: leaves contained 11.4% protein in the leaves and 50% FDA in the stems. The grass had higher amounts of B3/B2 proteins, which are less indigestible in leaves (17.16%). Forage production varied; the second cycle was better (leaf/stem 2.11). Despite a varied supplement intake, daily weight gain (1 kg/day) and carcass yield (49.23%) showed no differences, ensuring cost-effective, sustainable production. Incorporating supplements derived from coconut and palm kernel co-products enhances performance and carcass yield, comparable to standard supplements. This practice lowers production expenses, optimizes forage utilization, and enhances production chain sustainability, making it a recommended approach. The objective was to characterize the pastures by grazing cycle, as well as to evaluate the performance of buffaloes in intensive rotational grazing in a silvopastoral system in the eastern Amazon supplemented with agro-industry co-products in order to characterize the grazing cycles, the composition of the fractions, and the carcass yield. Fifteen non-castrated, crossbred water buffaloes (Murrah × Mediterranean) were used. All animals used in the study were clinically healthy and weighed approximately 458 kg. The animals were grazed in a single group, and supplementation (1% of live weight—LW/day) was divided into three treatments: control (control—conventional ingredients); Cocos nucifera coconut cake (Cocos nucifera) (coconut cake—70%); and palm kernel cake (Guinean elaeis) (palm kernel cake—70% palm kernel cake). The chemical composition of the forage is different in each part of the plant, with higher protein values in the leaves (11.40%) and higher acid detergent fiber (ADF) values in the stems (50.03%). Among the ingredients of the supplement, corn has the highest percentage of indigestible protein (35.57%), most of the protein in palm kernel cake is B3 (49.11%), and in Coco, B2 (51.52%). Mombasa grass has a higher percentage of B3 and B2 proteins; the indigestible fraction is lower in the leaves (17.16%). The leaf/stem ratio also varied between grazing cycles, being better in the second cycle (2.11%) and with an overall average of 1.71. Supplement consumption varied between cycles and was higher in the control treatment, with an overall mean of 4.74. There was no difference in daily weight gain and carcass yield, with an average of 1 kg/day and 49.23%, respectively. Therefore, it can be concluded that including supplements based on by-products from the coconut and palm oil agro-industries promotes performance and carcass yields compatible with conventional supplements. Their use reduces production costs, optimizes the utilization of forage mass, enhances the sustainability of the production chain, and, therefore, is recommended. [ABSTRACT FROM AUTHOR]

Simple Summary: The objective of this work was to evaluate the effects of climatic conditions and supplementation based on palm kernel cake, on the thermoregulation of crossbred buffaloes in the eastern Amazon. Over a 12-month period, 24 female buffaloes with an initial age of 54 ± 7 months and an average weight of 503.1 ± 23 kg were divided into four groups with different levels of palm kernel cake supplementation relative to body weight. The animals were kept in Brachiaria brizantha pastures with access to water and mineral salt. Supplementation did not influence the physiological variables of thermoregulation. Throughout the year, mean values of rectal temperature, respiratory rate and body surface temperature were higher in the afternoon (p > 0.05). Supplementation with palm cake did not result in influences on the thermoregulation of buffaloes in the study region. The respiratory rate showed an association with the annual seasonality of temperatures, with higher averages in the afternoons of the rainy season. The positive correlation between the rectal temperature, respiratory rate, and body surface temperature indicates that buffaloes respond to atmospheric thermal elevations (afternoon period), which is reflected in increasing thermal indices. In ruminants, diet composition has a positive correlation with heat production, which can influence thermoregulation, energy expenditure and, consequently, animal performance. The objective of this work was to evaluate the effects of climatic conditions and supplementation based on palm kernel cake, on the thermoregulation of crossbred buffaloes in the eastern Amazon. The research was carried out at Embrapa Amazônia Oriental (01°26′ S and 48°24′ W), Belém, Pará, and lasted 12 months (representing the entire year). Twenty-four buffaloes, females, with initial age and an average weight of 54 ± 7 months and 503.1 ± 23 kg, respectively, non-pregnant, non-lactating and clinically healthy were used, divided into four treatments based on the supplementation content of the palm cake (%DM) in relation to their body weight (%): 0, 0.25, 0.50 and 1.0. The animals were kept in paddocks with Brachiaria brizantha (cv. Marandu), in a rotating system, with water to drink and mineral salt ad libitum. Equipment was installed to record environmental data (temperature and relative humidity, dew point temperature, wet bulb and black globe) and physiological data: rectal temperature (RT); respiratory rate (RR); and body surface temperature (BST), recorded twice a day, always in the morning (6:00 a.m. to 7:00 a.m.) and afternoon (12:00 p.m. to 1:00 p.m.) shifts, and were used to calculate the Globe Temperature and Humidity Index (GTHI). Supplementation did not influence the physiological variables of thermoregulation (p > 0.05). However, there were differences in the GTHI between the shifts, with higher means in the afternoon shift, especially in the less rainy period of the year, where the GTHI reached 92.06 ± 2.74 (p < 0.05). In all periods of the year, the mean values of RT, RR and BST were higher in the afternoon shift (p > 0.05). The respiratory rate (RR) is associated with the annual seasonality of the thermal waters, with higher averages in the afternoons of the rainy season. The positive correlation for rectal temperature, respiratory rate and body surface temperature indicated that buffaloes respond to thermal elevations in the atmosphere (afternoon period) and, consequently, reflect on the GTHI. Supplementation does not influence thermoregulation; the changes observed occurred in response to the region's thermal and rainfall conditions (mainly in the afternoon shift), with higher GTHI values. [ABSTRACT FROM AUTHOR]

Simple Summary: Ewe nutrition during gestation, either in excess or in deficit, may influence fetal development and the postnatal life of the lamb. The objective of this study was to evaluate the effects of use the of energy (ME) and energy/protein (MECP) supplementation in the ewe's diet in the last third of gestation on maternal placental and endocrine characteristics, as well as on the behavior of neonatal lambs and productive performance. ME and MECP ewes had higher serum concentrations of triiodothyronine and cortisol on the day of lambing. However, only ME ewes had higher placental efficiency and lower total cotyledon weight. The ME and MECP diets increased birth weight at weaning and reduced the time to kneel, to try to stand, and the latency to stand of the lambs. It is concluded that overnutrition in the last third of gestation was positive for the sheep production system, with improved production rates, hormonal profile, placental characteristics and neonatal behavior. These results are valuable to society because they indicate a management strategy during the reproductive season that can be adopted by sheep producers to increase the productivity of their flocks. The objective of the study was to evaluate energy or energy/protein supplementation in the ewe diet, in the last third of gestation, on maternal placental and endocrine characteristics, as well as its effects on the behavior of neonatal lambs and productive performance until weaning. A total of 128 ewes were used, and the experimental diet was fed from 100 days gestation until lambing, with the birth of 172 lambs. The ewes were distributed into three treatments: CTL (control, n = 43) with metabolizable energy (ME) and crude protein (CP) intake according to NRC (1985); ME (energy supplementation, n = 44) plus 21% ME; and MECP (energy/protein supplementation, n = 41) plus 26% ME and CP. Body weight, body condition score, serum hormone concentrations, placental characteristics, lamb performance and behavior, and production efficiency of the ewe from lambing to weaning were measured. ME and MECP ewes were heavier before (p = 0.006) and just after lambing (p = 0.002) and had higher serum triiodothyronine (p = 0.001) and cortisol (p = 0.004) concentrations on the day of lambing. ME ewes had higher placental efficiency (p = 0.036) and lower total cotyledon weight (p = 0.011). ME and MECP diets increased both lamb birth weight (p = 0.015) and weaning weight (p = 0.009). Production efficiency at birth and at weaning was not influenced (p > 0.05) by treatments. Lamb behavior was influenced by the ME and MECP diets, reducing the time to kneel (p ≤ 0.05), to try to stand (p ≤ 0.05), and the latency to stand (p ≤ 0.005). It is concluded that overnutrition in the last third of gestation was positive for the ovine production system, with improved production rates, hormonal profile, placental characteristics, and neonatal behavior. [ABSTRACT FROM AUTHOR]

The present study compared the outcomes of in vivo embryo production in Morada Nova ewes subjected to either 9‐day (G‐9SOV, n = 21) or 12‐day (G‐12SOV, n = 21) progesterone (P4)‐based estruses synchronization protocol coupled with superovulatory treatment with decreasing doses of porcine follicle‐stimulating hormone (133 mg of pFSH given over 3 days). Non‐surgical embryo recovery (NSER) was performed 6–7 days after the onset of oestrus. Total antral follicle count doubled from the first to the sixth pFSH dose in both groups (p <.05). Oestrus responses did not vary between the two groups of animals (95.2%). Corpora lutea (CL) were detected in 85.0% and 60.0% of ewes that previously manifested oestrus behaviour in G‐9SOV and G‐12SOV respectively. NSER was successfully completed in 86.2% of ewes that had CL (p >.05). The mean number of CL per ewe/successfully flushed donor ewe was greater (p <.05) in G‐12SOV (12.3 ± 1.7/12.1 ± 1.9) than in G‐9SOV (7.9 ± 1.4/8.2 ± 1.6). Mean numbers of retrieved blastocysts and viable embryos were greater (p >.05) in G‐12SOV (5.8 ± 1.9 and 3.7 ± 1.7) than G‐9SOV (3.5 ± 1.1 and 0.8 ± 0.3 respectively). The total follicle count (all follicles ≥2 mm in diameter) at the sixth pFSH dose (at P4‐device removal) was positively correlated (p <.05) with the number of CL (r =.95) and viable embryos (r =.91) in G‐12SOV. The ewes with ≥10 Cl (48% of all flushed donors) yielded 80.5% of viable embryos. In summary: (a) Morada Nova ewes from G‐12SOV group had better superovulatory responses compared with G‐9SOV group; (b) total follicle count at the last pFSH dose was a good predictor of superovulatory responses only in the ewes primed with P4 for 12 days; and (c) animals with ≥10 ovulations are main contributors to viable embryo production in Morada Nova ewes. [ABSTRACT FROM AUTHOR]

Fetal programming refers to the concept in which factors that affect the health and performance of the pregnant mother can have long-term effects on the offspring, through stimulation or injury during critical periods of gestation, which modulate fetal development and interfere with the performance of the offspring. The aim of this study was to evaluate the effect of early and conventional weaning on cytochrome C oxidation of 3,3'-Diaminobenzidine (DAB), which characterizes the functionality of the mitochondrial membrane, in subsequent male offspring generated by primiparous or multiparous females. Fifty-six Nelore males were evaluated, with an average initial age of 12.5 months. During the fetal development of these animals, their primiparous or multiparous mothers weaned calves at 150 or 240 days (early or conventional weaning, respectively). Thus, of the 56 animals used, 29 came from primiparous females, 14 from the early weaning group and 15 from conventional weaning. The other 27 animals came from multiparous females, 13 from the early weaning group and 14 from conventional weaning. Semen was collected at 12.5, 14.3, 15.5 and 17.3 months of age, using the electroejaculation technique. The functionality of the mitochondrial membrane was assessed by the ultracytochemical test of in situ cytochrome C oxidase activity. For this, an aliquot of 80 μL of semen incubated with 80 μL of DAB (diaminobenzidine - 1 mg/mL in Dulbecco's phosphate buffered saline - DPBS) at 37°C for one hour was used. After incubation, three smears were taken and fixed in 10% formaldehyde for 10 minutes. The slides were air-dried under protection from light and then evaluated under light microscopy at 1000x magnification. Two hundred cells were evaluated per sample and classified into four classes: DAB I: sperm with a fully stained midpiece, with practically all the mitochondria active, indicating high mitochondrial activity. DAB II: sperm with more than half of the mitochondria stained, indicating medium to high mitochondrial activity. DAB III: sperm with less than half of the mitochondria stained, indicating low mitochondrial activity. DAB IV: sperm with the middle part completely unstained, indicating no mitochondrial activity. The results were expressed as a percentage of each subpopulation in the sample. Statistical analyses were carried out using SAS software (Version 9.2; SAS Institute), analyzed by ANOVA using a mixed model (PROC MIXED). When a significant treatment effect was detected, the means were compared using Fisher's method of least significant difference for multiple comparisons. A significant difference was considered when P ≤ 0.05. There was no effect of weaning, mother, or interaction between weaning, mother and age (p > 0.05). However, there was an age effect for mitochondrial membrane potential (p < 0.01), with the data expressed as mean ± standard error of the mean: DAB I: 40.7c ± 3.6, 62.9b ± 2.6, 70.4a ± 2.3 and 70.3a ± 2.1; DAB II: 39.6a ± 2.8, 28.3b ±2.1, 21.6c ± 1.8 and 26.4bc ± 1.6; DAB III: 9.7a ± 0.9, 2.2b ± 0.7, 1.6b ± 0.6 and 1.1b ± 0.5; DAB IV: 13.6a ± 1.8, 6.6b ± 1.4, 6.5b ± 1.2 and 2.3c ± 1.1 when assessed at 12.5, 14.3, 15.5 and 17.3 months of age, respectively. The results of this study show that early or conventional weaning, using two classes of mothers, has no effect on the functionality of the mitochondrial membrane in the offspring of Nelore males. However, when evaluating the sperm of Nelore breed animals in the prepubertal and pubertal stages, it was possible to observe that as the animals get older, the functionality of the mitochondrial membrane becomes better. It can be concluded that there was no effect of fetal programming when using early and conventional weaning on the subsequent offspring of Nelore males sired by primiparous or multiparous mothers, but the functionality of the mitochondrial membrane becomes better as the Nelore males get older. [ABSTRACT FROM AUTHOR]

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The Brazilian Amazon has witnessed, in the last decades, an increase in the water buffalo (Bubalus bubalis) inventory, with interesting productivity results. As the Brazilian Amazon contains the main water buffalo population in the Americas, the aim of this work is to review its most relevant production systems and some peculiarities about meat and milk production in this territory. The opening section describes the Amazon Basin, the most common water buffalo breeds, a brief history of the local livestock farming beginning in 1644. Also, it presents how water buffaloes gradually replaced bovine herds, especially where the latter had a lower productive performance. The use of extensive or more intensified models is pointed out and the ecosystems in which buffaloes are raised are detailed since native or cultivated pastures can be used in floodplains or drylands. Buffalo raising is favored in the Amazon due to the climate, soil, genetic variability of forages, animal adaptability, and physical space. Thus, it is clear that buffaloes have a high potential for meat and milk production and are an alternative in the use of altered areas of the Amazon; and, in the recent past, the low profitability of buffalo farming in traditional production systems in the Amazon was the reason which made this activity economically unattractive. Most recent technologies as outdoor confinements and silvopastoral systems are pointed out as more suitable regarding land-use policies, and buffalo farming for meat and milk production fits perfectly in this context, with productivity and beneficial socioeconomic. [ABSTRACT FROM AUTHOR]

Climate change is a reality and global surface temperature is projected to rise substantially in the next 80 years. Agriculture practices will have to adapt to climate change, and also help to mitigate this effect using, among other strategies, forest conservation and management. Silvopastoral systems have been adopted in tropical climate livestock areas but their benefits on thermal comfort and reproductive performance of beef cows are not completely known. Therefore, our aims were to compare the microclimate of silvopastoral and intensive rotational unshaded grazing systems in different months and to evaluate physiological variables (Exp. 1 and 2), metabolism, and in vitro embryo production (Exp. 2) in crossbred beef females. Our hypothesis is that the silvopastoral system can improve the thermal comfort of beef heifers and cows and, consequently, also improve dry matter intake, body weight gain, and in vitro embryo production when compared to the unshaded rotational grazing system. In Exp 1, the silvopastoral system decreased body temperature and increased welfare and performance of heifers. In Exp. 2, the silvopastoral system enhanced the body weight but did not affect metabolism and the general reproductive performance, but increased the recovery rate of oocytes in primiparous cows. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the viability of using transponders for the electronic identification of water buffaloes and compare their efficiency when used in animals of different age groups. Electronic transponders with RFID technology (2.1 × 12.2 mm) were implanted subcutaneously (D0) in the scutiform cartilage. The animals consisted of four groups: CLF-I (17 calves; 2.1 ± 1.9 months), CLF-II (20 calves; 5.1 ± 3.2 months), HFR (20 heifers; 22 ± 4.7 months) and STR (19 steers; 26.6 ± 6.7 months). The animals were kept under pasture grazing, a part of the year in the dryland and a part in the floodplain, and were monitored for up to 350 days. The average time required for individual transponder implant was 49.46 s, while the time required for reading the code was 3.76 s. The older calves required higher time for individual implant (P = 0.0001) and closer approximation of the reader in the D150 (P = 0.0001). The mean read distance was 2.98 cm in D0 and 1.94 cm in D150. The magnitude of the subcutaneous transponder migration was minimal, and was within an area of 17.2 mm2. A slight bleeding was observed in 15.79% of the animals during the implant. A decreasing incidence of edema was observed until D21, with the heifers being more sensitive until that time (P = 0.0099). Considering the results, it is preferred to implant electronic transponders in calves up to two months of age. The physical rate of transponder loss was 1.3% and the loss of functionality was 9.2%. High reading rate was achieved when animals were raised both in dryland (93.9%) and floodplain (97.2%). Thus, the electronic identification of water buffaloes is a technique capable of replacing traditional and rudimentary methods to identify buffaloes and can provide safe identification of animals. [ABSTRACT FROM AUTHOR]

Morada Nova breed sheep are without wool, tropicalized, small-sized animals, known for their high-quality meat and skin. Their body development naturally depends on the genetic potential and adequate nutritional support, which suggests that the offer of high-energy density diets positively influences their productive indicators. Thus, the present study investigated the effect of a high-energy diet for the Morada Nova lambs on body development and testicular function, considering their histomorphometric characteristics and seminal quality. Forty-two males (19.2 weeks, 20.7 ± 3.5 kg) were equally divided into two groups and fed with 2.05 Mcal (G7, n = 21) or 2.37 Mcal (G24, n = 21) of metabolizable energy/day, equivalent to 7% and 24% above the minimum for growing lambs. The animals were confined for 23 weeks (W0 to W23). Weight and body score differed significantly from the W1 (P < 0.05). From the W5, thoracic perimeter, body length, wither height, and rump attributes were higher in G24 (P < 0.05). The scrotal circumference and testicular volume were higher in G24 from the W3 (P < 0.05). Although testosterone levels were not affected (P = 0.05), the highest energy intake increased the diameter of the seminiferous tubules and the development of the epididymal epithelium (P < 0.05). This positively influenced the seminal quality and reduced the minor defects (21.87% vs. 17.13%) and the total spermatic defects (26.34% vs. 21.78%, P < 0.05). Thus, it is possible to employ higher levels of dietary energy for Morada Nova young males to express higher productive efficiency and earlier reproductive attributes of interest. [ABSTRACT FROM AUTHOR]

It is believed that increased livestock production is limited by tropical climate. Thermal imbalance in bulls can lead to hyperthermia and alter testicular metabolism, causing subfertility or infertility. Therefore, the thermoregulation of composite Canchim bulls (5/8 Charolais × 3/8 Zebu) raised in tropical climate as well as their consequences in the physiological, hematological, hormonal, and andrological parameters were evaluated monthly. The bulls (n = 18; 30.0 ± 1.5 months; 503.8 ± 23.0 kg) were kept on pasture, in a single group, from August 2015 to March 2016, comprising the winter, spring, and summer seasons. Biometeorological variables were continuously monitored, and the Temperature and Humidity Index (THI) was calculated. A greater thermal challenge occurred in spring and summer (THI ≥ 72.0). Nevertheless, the bulls exhibited normothermia (38.6 to 38.9 °C) in these seasons. The cortisol did not vary between seasons (7.0 vs. 8.7 vs. 6.8 ng/mL; P > 0.05) and remained within the physiological patterns. Independent of the seasons, stress leukogram was also not observed, refuting the incidence of acute or chronic thermal stress. It is noteworthy that T3 and testosterone increased (P < 0.0001, P < 0.05) in spring and summer, the time that coincides with the breeding season, when there is increased metabolic requirement from the bulls. The progressive thermal challenge increase did not affect the scrotal thermoregulatory capacity, and in general, scrotal temperature remained at 5.2 °C below the internal body temperature. In summer, there was a 5% reduction in the minor sperm defects (P < 0.05) and DNA fragmentation in 2.4% of spermatozoa, a compatible value for high fertility bulls. The results show that the studied composite bulls can be considered as climatically adapted and constitute a viable alternative to be used in production systems in a tropical climate, even if the breeding seasons occur during the most critical thermal condition periods of the year. [ABSTRACT FROM AUTHOR]

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Our aim was to evaluate the effects of three thermal environments over time on kinetics, functionality and in vitro fertility of cryopreserved bovine spermatozoa. Four ejaculates from five bulls (n = 20) were cryopreserved. After thawing, semen was evaluated (0 hr), incubated for 4 hr in T36.0 (36.0°C), T38.0 (38.0°C) and T39.5 (39.5°C), and analysed every hour (1 hr, 2 hr, 3 hr, 4 hr). In vitro production of embryos was performed at 0 hr and 4 hr. Sperm motility and cell kinetics (Computer‐Assisted Sperm Analysis) were impaired after 2 hr at T38.0 and T39.5 (p < 0.05). Flow cytometry revealed an increase in the cells with injured plasma membrane to 39.5°C and a general reduction in the mitochondrial potential over time (p < 0.05). In vitro fertility was impaired in all temperatures after 4 hr, but there was no difference between 36.0°C and 38.0°C. Our results suggest that the ex situ resilience of semen at 36.0°C after thawing with no major damage to the quality is limited to 3 hr. In normothermia or in thermal stress, sperm cells present a gradual reduction of movement and functionality, which were more significant after 1 hr of incubation. The in vitro production of embryos is impaired when the semen is kept in a thermal environment ≥36.0°C for 4 hr. [ABSTRACT FROM AUTHOR]