Nelore Cows Research Articles

Injectable progesterone in 13-month-old prepubertal Nellore heifers: effects on in vitro embryo production and pregnancy rate.

The aim of this study was to evaluate the effect of injectable progesterone administration before ovum pick-up (OPU) on in vitro embryo production (IVEP) and pregnancy rate in prepubertal Nellore heifers. Twenty-three Nellore females, 13.04 ± 0.8 months of age, were randomly assigned to two groups: control group (no progesterone application) and progesterone group (intramuscular administration of 1 mL [150mg/mL] progesterone 7 days before OPU). The second OPU was performed after 28 days (crossover between groups). After OPU, oocytes were selected for IVEP and a sample was fixed in 4% paraformaldehyde. Viable oocytes were subjected to immunofluorescence staining for IGFBP2 and caspase-3. For each oocyte, one image was generated per channel (A555 and A488 filters) and analyzed with the ImageJ program for the quantification of fluorescence intensity (in pixels). The produced embryos were transferred to multiparous Nellore cows and pregnancy was diagnosed by ultrasound 30 days after transfer. Data were analyzed using the MIXED and GLIMMIX procedure of SAS®. Treatment with injectable progesterone had no effect on the number or size of the antral follicles of heifers. No differences between the control and progesterone groups were observed for total number of aspirated oocytes (P = 0.78), viable oocytes (P = 0.80), cleavage rate (P = 0.60), or blastocyst rate (P = 0.56). There were no differences in pixel intensity between the two groups, nor in the levels of IGFBP2 or caspase-3. However, a difference was observed in the pregnancy rate of embryos produced from heifers of the progesterone group (42.1%; 32/76) when compared to the rate of embryos produced from control heifers (28.4%; 23/81) (P = 0.02). The use of injectable progesterone before OPU in prepubertal Nellore heifers does not improve IVEP but increases the pregnancy rate after transfer.

The metabolomic composition of the oviductal fluid is controlled by the periovulatory hormonal context in Bos indicus cows.

In cattle, oviductal function is controlled by the ovarian sex-steroids estradiol and progesterone. Here, we tested the hypothesis that the exposure to contrasting sex-steroid milieus differentially impacts the oviductal fluid composition. Estrous cycles of non-lactating, multiparous Nelore cows were pre-synchronized and then synchronized with a protocol designed two induce ovulation of large (LF group) or small (SF group) follciles. Larger preovulatory follicle (day 0) and corpora lutea (day 4) and greater estradiol (day 0) and progesterone (day 4) concentrations were observed in the LF group. Four days after induced ovulation, oviductal fluid was collected post-mortem. Quantitative mass spectrometry was used to determine the concentration of amino acids, biogenic amines, acylcarnitines, phosphatidylcholines, lysophosphatidylcholines, sphingomyelins, hexoses, prostaglandins and related compounds. Multivariate analyses (OPLS-DA) were conducted to compare the metabolomic signatures of oviductal fluids. Correlation network analysis was conducted to measure the strength and hierarchy of associations among metabolites. Of the 205 metabolites quantified, 171 were detected in at least 50% of the samples and were included in further data analysis. After OPLS-DA analysis, samples of the LF and SF were divided clearly into two non-overlapping clusters. Twenty metabolites had different or tended to have different concentrations in the oviductal fluid when comparing groups. Seven of these 20 analytes had greater concentrations in LF cows. Moreover, total sum of biogenic amines, phosphatidylcholines, and prostaglandins were higher in the SF group. The correlation network showed that the LF group metabolites' concentrations were highly intercorrelated, which was not observed in the SF group. We concluded that the periovulatory endocrine milieu regulates the composition of the oviductal fluid.

PSVII-14 Influence of dam parity and weaning strategy in previous lactation on feedlot performance of Nellore steers

Abstract In tropical beef cattle production systems, the impact of seasonality may be particularly challenging for young cows (primiparous or secondiparous) due to their increased nutritional requirements, encompassing maintenance, growth, gestation, and, in the case of secondiparous cows, lactation. Literature indicates that extending the duration of lactation during gestation is associated with decreased performance of progeny in their postnatal life. Therefore, implementing an early weaning approach can be an effective strategy to alleviate the nutritional demands of lactation in dams, thereby allocating more nutrients for fetal growth. This study aimed to evaluate the effect of early weaning on the feedlot performance of progeny that were in utero at the time of weaning intervention. To create experimental units, secondiparous and multiparous Nellore cows were assigned to one of two weaning strategies, where suckling calves were either; 1) early weaned 150 d (EW); or 2) conventional weaned at 240 d (CW). All calves were weaned at 150 d of lactation in 2022. Three bulls were used: Bull 1: had 13 calves with multiparous cows, had 7 calves with secondiparous cows, comprising 11 EW and 9 CW; Bull 2: had 10 calves with multiparous cows, had 6 calves with secondiparous cows, comprising 6 EW and 10 CW; and Bull 3: had 7 calves with multiparous cows, had 15 calves with secondiparous cows, comprising 11 EW and 11 CW. All cows were managed similarly after weaning, and through parturition, and weaning of subsequent calf, with resulting calves used for the current experiment. Nellore bulls (n = 57) with an initial body weight (BW) of 417.23 ± 9.12 kg and 18 mo of age were allocated to feedlot pens (equipped with Intergado equipment) and fed a common total mixed ration (80:20; concentrate:corn silage) for 97 ± 1.60 d. Bulls were distributed in a randomized complete block in a 2 × 2 factorial arrangement, considering dam weaning strategy in the previous lactation (EW and CW) and dam parity at subsequent calving (multiparous or secondiparous cows, MC and SC, respectively). Data were analyzed using PROC MIXED of SAS 9.4, with a model including the effects of dam weaning strategy, dam parity, and their interaction. Data were considered significant when P values were less than 0.05 and indicated a trend when 0.05 < P ≤ 0.10. There was an interaction between weaning strategy and cow parity, with calves born to SC-CW having reduced initial (P = 0.04) and final BW (P = 0.01) compared with all other groups (Figure 1 and 2). Steers from MC had greater dry matter intake (P = 0.003), and greater biological efficiency (P = 0.03; Table 1). Early weaning improved the final BW of steers born to secondiparous cows, suggesting it could be a strategy to enhance the performance of offspring and the reproductive performance of both secondiparous and multiparous cows.

261 Vitamin A administration in pregnant cows or newborn calves: Growth performance and carcass traits

Abstract This study aimed to evaluate the effects of Vitamin A (VA) injection on the growth performance and carcass traits of Nellore × Angus crossbred steers and heifers. For that, the same sire inseminated Nellore cows from two artificial insemination (AI) groups were randomly assigned to one of three treatments at 250 d of gestation: no VA injection (Control); VA injection in pregnant cows at 250 d of gestation (VAcow; 2,000,000 IU single dose); VA injection in newborn calves at birth and 60 d of age (VAcalf; 200,000 IU each dose). Cow-calf pairs were kept in the same paddock, and calves received creep-feeding supplementation from 90 d of age to weaning. After weaning, steers and heifers [n = 36; body weight (BW) 213 ± 25.7 kg] were stratified by treatment and BW and allotted into 16 pens. After 207 d of feeding (77 d of growing diet + 130 d of finishing diet), steers and heifers were slaughtered at a commercial abattoir. Data were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of VA injection, sex, and VA injection*sex interaction. The random effects were animal, AI group, and cow parity. Average daily gain before weaning (P < 0.01) and final BW in the finishing phase were greater (P = 0.04) in VAcow steers compared with heifers from all treatments (Table 1). Vitamin A had a positive impact on weaning BW of male calves and a negative impact on heifers (P < 0.01). There was no treatment difference (P = 0.35) in feedlot average daily gain (ADG), but steers had greater (P = 0.03) ADG compared with heifers. Moreover, VAcow steers had greater dry matter intake (DMI) in the feedlot (P = 0.04) compared with other treatments, and there was no effect of VA on DMI of heifers. On the other hand, feedlot feed efficiency tended to be greater (P = 0.07) in Control steers compared with other treatments, with no VA effect on heifers too. The ribeye area was greater (P = 0.04) in VAcow steers than in Control steers and heifers from all treatments. Intramuscular fat content was greater (P = 0.04) in VAcow steers than in Control and VAcalf steers. However, there was no effect of VA on heifers and VAcow steers. In addition, VAcow treatment tended (P = 0.08) to increase backfat thickness. In conclusion, VA injection in pregnant cows can be a strategy to improve marbling in steers, but there is no effect on intramuscular fat in heifers. Additionally, VA injection in pregnant cows produced intramuscular content in beef of steers, similar to heifers.

Optimisation of Early Pregnancy Diagnosis andResynchronisation in Beef Cows.

The objectives of this study were (1) to investigate the effects of the preovulatory follicle (POF) size on the accuracy of Doppler-based early pregnancy detection, and (2) to determine whether the removal of PGF2α (PGF) treatment during the resynchronisation protocol would affect fertility in beef cows. In Experiment 1, Nelore suckling cows (n = 224) were enrolled in an estradiol-progesterone-based timed artificial insemination (TAI) protocol. At TAI, cows were separated based on the range of POF diameters, as follows: ≤11.0 mm (n = 50), 11.1-12.9 mm (n = 64), 13.0-14.4 mm (n = 62) and ≥14.5 mm (n = 48). On day 22 after TAI, the corpus luteum (CL) blood flow (CLBF) of all cows was examined by colour Doppler ultrasonography to diagnose nonpregnant cows. The cows with the largest POF had the greatest positive predictive value (88.6%; 31 of 35) and diagnostic accuracy (91.7%; 44 of 48). In Experiment 2, Nelore cows (n = 233) were subjected to the same TAI protocol. Fourteen days after TAI, all cows were started on a resynchronisation protocol. Cows diagnosed as nonpregnant based on CLBF, on day 22, received 0.5 mg estradiol cypionate intramuscular (im) and were assigned to receive either 150 μg of PGF (PGF; n = 50) or 2 mL of saline (control; n = 47). Cows treated with PGF had a P/AI of 30.0% compared with a 48.9% P/AI in controls (p = 0.06). Our findings demonstrate that the POF size affects the accuracy of a CLBF-based early pregnancy diagnosis and that the removal of PGF treatment from the resynchronisation protocol tended to increase P/AI of the second TAI.

Performance and Metabolic Responses of Nellore Cows Subjected to Different Supplementation Plans during Prepartum.

This study assessed the effects of different prepartum supplementation plans on Nellore cows' performance, metabolic responses, and early offspring development. Thirty-nine pregnant Nellore cows (224 ± 2.67 days of pregnancy, 5.3 ± 0.29 years of age, body weight 520 ± 15.2 kg, initial body condition score 6.0 ± 0.07) were assigned to one of four treatments: a control group receiving only mineral mixture ad libitum, and three groups receiving daily protein-energy supplements of 2, 4, or 6 g/kg BW for 60 days prepartum. Weights and body condition scores were evaluated at the start of the experiment, 7 days before calving, and at 45 and 90 days postpartum. Cows supplemented with 4 and 6 g/kg BW showed improved body weight and body condition scores prepartum and postpartum and had a shorter service period (p < 0.05). The highest blood urea nitrogen concentrations were observed in cows receiving 6 g/kg BW (p = 0.0124). There was a reduction in blood urea nitrogen at calving for the 6 g/kg BW group, while the control group showed an increase (p < 0.001). Non-esterified fatty acids concentrations were lower 21 days before calving for the 4 and 6 g/kg BW groups compared to the control (p < 0.05) and decreased postpartum for all treatments (p < 0.001). No significant differences were observed in calf birth weight or performance. Supplementing with 4 g/kg BW of protein-energy is recommended to enhance metabolic health and overall performance.

Performance and metabolic evaluation in primiparous beef cows under grazing at different breeding ages.

We aimed to evaluate the metabolic and performance differences in primiparous Nellore cows, which became pregnant at 14 or 24-mo old. Thirty-eight cows with 202 ± 5 days of gestation were divided into two treatments according to breeding age: 14 or 24-mo. Cows were evaluated for body weight (BW), body condition score (BCS), carcass characteristics, milk yield, calves's performance, and blood characteristics. The animals were managed in eight paddocks under continuous grazing and evaluated from 90 d before parturition until 240 d after calving. We observed an interaction between breeding age and time (P < 0.01) for cow BW. Both breeding age categories experienced BW loss during parturition, with a concurrent decrease in BCS. However, following their first calving, the BW of 24-mo cows remained stable (P > 0.05), whereas 14-mo cows exhibited a gradual recovery in BW after parturition (P < 0.05). Milk yield was greater in 24-mo animals (P < 0.01), but decreased with increasing milking days (p < 0.05) for both groups. The weight gain calves from the heifers bred at 24-mo was greater (P < 0.01), which reflected in greater BW at weaning. The beta-hydroxybutyrate (β-OHB) concentration was greater before calving and a marked decrease after parturition (P < 0.05). The 24-mo cows had greater blood β-OHB (P < 0.01) at prepartum and 30 days after calving. Blood progesterone was greater in 24-mo cows (P > 0.05). Primiparous beef cows that conceive at either 14 or 24-months of age exhibit distinct nutritional requirements and metabolic profiles. Notably, cows that conceive at 24-months of age have the advantage of weaning heavier calves and displaying a more consistent reproductive cycle following their first calving than cows that conceive at 14-months.

Effects of supplementation of grazing Nellore cows with β-carotene and vitamins A + D3 + E + biotin on follicle diameter, oestrus, establishment of pregnancy, and foetal morphometry.

The objectives of this experiment were to evaluate the effects of supplementation of Nellore (Bos indicus) cows with β-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 + β-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 β-carotene and vitamins A + D3 + E + biotin.

Superovulating cattle with corifollitropin-alpha, a long-acting recombinant human FSH (rhFSH): Dose-response, half-life, effects on the ovaries, and embryo outcomes

The aim of this study was to evaluate the superestimulatory and superovulatory responses of cattle treated with corifollitropin-alpha, a long-acting human recombinant FSH (rhFSH). In the first and second experiments, we used Nelore (Bos indicus) heifers previously submitted to follicular wave suppression by active immunization against GnRH. In Experiment 1 (a dose-response study), heifers (n = 20) were randomly allocated into five groups, which received placebo (saline) or a single sc dose of 7.5, 15.0, 22.5 or 30.0 μg rhFSH. The heifers were subjected to daily ovarian scan and blood sampling during 11 days. We observed group, time, and group x time effects (P<0.0001) for both average follicle size and circulating FSH concentrations, with a strong correlation (R = 0.82, P<0.0001) between the area under curve (AUC) for both parameters. The peak concentration of FSH 24h after treatment and average follicle size at all timepoints, however, were similar (P>0.05) between groups 22.5 and 30.0 μg. In Experiment 2, heifers (n = 18) were allocated into three groups, which received (0h) either placebo (control), 25 μg rhFSH or 130 mg pFSH (Folltropin). There was no difference (P>0.05) in average follicle size at any moment, as well as in intrafollicular E2 at 120h or in plasma P4 seven days later between groups rhFSH and pFSH. In Experiment 3, cycling Nelore heifers (n = 20) were subjected to a wave synchronization protocol and superovulated (day 0) using a standard pFSH protocol (120 mg split in eight decreasing im doses) or with a single sc injection of 20 μg rhFSH. The number of follicles >7 mm on day 4 did not differ (P=0.4370). Heifers receiving rhFSH had greater average follicle size on day 4 (P=0.0005), ovulation rate (P<0.0001), and number of CL (P=0.0155), as well as a trend towards a greater number of ova (P=0.07) and viable embryos (P=0.0590). In Experiment 4, superovulation was induced with a single sc injection of 25 μg rhFSH in Girolando and Nelore cows and heifers (n = 20). None of the embryo yield endpoints differed between the two breeds (P>0.05). In conclusion, cattle superstimulation and superovulation can be successfully induced with a single dose of a long-acting rhFSH (corifollitropin-alpha).

Effects of prepartum supplementation levels on the performance and metabolic responses of Nellore cows in a grazing system

This study aimed to evaluate the effects of prepartum supplementation levels on the productive and nutritional performance and metabolic responses of Nellore cows in a grazing system. Forty-four pregnant Nellore cows multiparous with an initial mean gestation time of 230 days, average initial body weight (BW) of 541 ± 19 kg, and body condition score (BCS) of 5.5 ± 1.7 were used and distributed in a completely randomized design, with four treatments and 11 cows per treatment. The treatments evaluated consisted of four supplementation levels in the prepartum period with a duration of 60 days, according to the following scheme: 0.0 (Control = CON); 0.5 (LOW); 1.0 (Medium = MED) and; 1.5 (High = HIG) kg per animal day-1 of supplement. The supplement was composed of wheat meal and urea, and formulated to contain 22% of crude protein (CP). A positive linear effect (P &lt; 0.05) was observed on the intake of CP and CP:digested organic matter (DOM) ratio as supplementation levels were increased. In addition, a quadratic effect (P &lt; 0.05) was detected on the intake of neutral detergent fiber corrected for ash and protein (apNDF), digested neutral detergent fiber, and DOM with increasing supplementation levels in the prepartum period, in which MED cows had higher intakes compared to CON, LOW, and HIG cows. Prepartum supplementation levels did not affect (P &gt; 0.10) the average daily gain in the prepartum or postpartum periods and, BCS of the dams, and BW of calves at birth or 45 days of age. In the prepartum period, supplementation levels did not affect (P &gt; 0.10) the blood concentrations of total proteins, albumin, globulins, glucose, cholesterol, triglycerides, non-esterified fatty acids, and beta-hydroxybutyrate in the experimental cows. In conclusion, the provision of 1.0 kg of supplement per animal per day during the last 60 days of pregnancy improves prepartum nutritional performance and postpartum milk production of grazing beef cows.

Exploration of mobile genetic elements in the ruminal microbiome of Nellore cattle

Metagenomics has made it feasible to elucidate the intricacies of the ruminal microbiome and its role in the differentiation of animal production phenotypes of significance. The search for mobile genetic elements (MGEs) has taken on great importance, as they play a critical role in the transfer of genetic material between organisms. Furthermore, these elements serve a dual purpose by controlling populations through lytic bacteriophages, thereby maintaining ecological equilibrium and driving the evolutionary progress of host microorganisms. In this study, we aimed to identify the association between ruminal bacteria and their MGEs in Nellore cattle using physical chromosomal links through the Hi-C method. Shotgun metagenomic sequencing and the proximity ligation method ProxiMeta were used to analyze DNA, getting 1,713,111,307 bp, which gave rise to 107 metagenome-assembled genomes from rumen samples of four Nellore cows maintained on pasture. Taxonomic analysis revealed that most of the bacterial genomes belonged to the families Lachnospiraceae, Bacteroidaceae, Ruminococcaceae, Saccharofermentanaceae, and Treponemataceae and mostly encoded pathways for central carbon and other carbohydrate metabolisms. A total of 31 associations between host bacteria and MGE were identified, including 17 links to viruses and 14 links to plasmids. Additionally, we found 12 antibiotic resistance genes. To our knowledge, this is the first study in Brazilian cattle that connect MGEs with their microbial hosts. It identifies MGEs present in the rumen of pasture-raised Nellore cattle, offering insights that could advance biotechnology for food digestion and improve ruminant performance in production systems.

Impact of 17β-estradiol administration at the moment of timed-AI in Nelore cows with small dominant follicle or not showing estrus

We aimed to evaluate the effects of administering estradiol (E−17β) 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−17β-based protocol (day 0) for synchronization of ovulation. On day 7, devices were removed, cows received 1 mg E−17β 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−17β) and E−4 (4 mg E−17β). 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−17β, 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−17β (ESR1 and ESR2), oxytocin (OXTR), and P4 (PGR). In Experiment 3 (Exp3), 3829 suckled cows were submitted to a P4/E−17β-based protocol for TAI. On day 9, devices were removed and cows received 1 mg E−17β 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−17β; n = 363). In Exp1, plasma E−17β concentrations increased at 4 h after treatment in a dose-dependent manner but reduced at 12 h. The E−17β-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−17β doses in estrus or ovulation rate. In Exp2, the interval from treatment to ovulation was longer (P < 0.05) in the E−17β group. GnRH-treated cows showed higher ovulation rates (89 vs. 35 %) compared to cows not treated with GnRH, as E−17β-treated cows (P < 0.01) had a lower ovulation rate compared to those not receiving E−17β (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−17β 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.

PSVI-3 Effects of dried distillers grains on performance of suckling beef calves in a creep-feeding system

Abstract Dried distiller’s grains (DDG) have been successfully used in beef cattle diets due to their high protein content and increasing availability around the world. However, the chemical composition of DDG varies according to the type of fermented grain and processing methods, and its increased sulfur content can compromise animal performance. There are few studies evaluating DDG in supplements for beef calves in creep-feeding systems. Hence, our objective was to assess the effects of DDG on performance of suckling beef calves in a creep-feeding system. Nellore×Red Angus male calves (n = 37), weighing 162 ± 4.06 kg at 120 d of age, along with their respective dams (n =37 Nellore cows) were used. The cow-calf pairs were randomly assigned into eight paddocks formed by Urochloa decumbens pastures. Animals were subjected to a 14-dadaptation period and an additional 108-d period for performance evaluation. All animals had access to water and mineral mixture ad libitum. Four treatments were evaluated, as follows: control (mixture mineral only), supplement without DDG, or supplements including 375 and 750 g/kg DDG [dry matter (DM) basis]. The supplements were composed of ground corn, soybean meal, urea, and DDG, planned to contain 300 g CP/kg DM, and provided daily at 7.0 g/kg body weight (BW; as fed). Treatments were assigned to experimental units (i.e., calf) in a completely randomized design. Calves were weighed at the beginning and end of the experiment, as well as every 15 d, to adjust the amount of supplement to be provided. Comparisons between treatments were performed by decomposing its sum of squares into orthogonal effects as follows: 1) control (mineral mixture only) versus supplemented calves; 2) evaluation of the linear and quadratic effects of the inclusion of DDG in the supplements. Data were analyzed using the MIXED procedure of SAS 9.4 (α = 0.05). Supplementation enhanced (P &amp;lt; 0.05) average daily gain (ADG) and final body weight (FBW) when compared with control. On average, ADG was increased from 0.94 kg/d to 1.08 kg/d for control and supplemented calves, respectively. On the other hand, ADG and FBW decreased linearly as the DDG inclusion in the supplement increased (P &amp;lt; 0.05). The differential ADG of calves that received supplements with 375 and 750 g/kg DDG compared with calves that did not receive DDG was -0.046 and -0.096 kg, respectively. It is worth emphasizing that calves fed supplements with 375 g/kg and 750 g/kg DDG had a 14% and 46% less supplement intake, respectively, than animals that were not fed DDG. Supplementing beef calves in a creep-feeding system enhances animal performance. However, the inclusion of high DDG levels in supplements decreases the performance of suckling beef calves.

Evaluation of Muscle Long Non-Coding RNA Profile during Rearing and Finishing Phase of Bulls Subjected to Different Prenatal Nutritional Strategies.

Maternal nutrition has the ability of influence critical processes in fetal life, including muscle development. Also, in this period, epigenetic sensitivity to external stimuli is higher and produces long-lasting effects. Thus, the aim of this study was to investigate epigenetic mechanisms, including the identification and characterization of long non-coding RNA (lncRNA) from animals that had undergone different strategies of prenatal supplementation. A group of Nellore cows (n = 126) were separated into three nutritional plans: NP (control)-Not Programmed, without protein-energy supplementation; PP-Partially Programmed, protein-energy supplementation in the final third of pregnancy; and CP-Complete Programming, protein-energy supplementation during the full period of gestation. A total of 63 male offspring were used in this study, of which 15 (5 per treatment) had Longissimus thoracis muscle at 15 (biopsy) and 22 months (slaughter). Biopsy samples were subjected to RNA extraction and sequencing. Differential expression (DE) of remodeling factors and chromatin-modifying enzyme genes were performed. For the identification and characterization of lncRNA, a series of size filters and protein coding potential tests were performed. The lncRNAs identified had their differential expression and regulatory potential tested. Regarding DE of epigenetic mechanisms, no differentially expressed gene was found (p > 0.1). Identification of potential lncRNA was successful, identifying 1823 transcripts at 15 months and 1533 at 22 months. Among these, four were considered differentially expressed between treatments at 15 months and 6 were differentially expressed at 22 months. Yet, when testing regulatory potential, 13 lncRNAs were considered key regulators in the PP group, and 17 in the CP group. PP group lncRNAs possibly regulate fat-cell differentiation, in utero embryonic development, and transforming growth factor beta receptor, whereas lncRNA in the CP group regulates in utero embryonic development, fat-cell differentiation and vasculogenesis. Maternal nutrition had no effect on differential expression of epigenetic mechanisms; however, it seems to impair lncRNA regulation of epigenetics.

Effects of equine chorionic gonadotropin dosage and its splitting in different days on reproductive performance of Nellore cows synchronized for timed-artificial insemination

This study evaluated the effects of dose of equine chorionic gonadotropin (eCG) and its splitting in different days of the synchronization protocol on reproductive performance of primiparous and multiparous Nellore cows. In the present study, 2,536 Nellore cows (1,634 primiparous and 902 multiparous) were assigned to receive in a 2 × 2 factorial design 1) an intravaginal progesterone (P4) device and 2.0 mg of estradiol benzoate (EB) on day −11, 12.5 mg (i.m.) of dinoprost tromethamine (PGF), 300 IU (i.m.) of eCG, 0.6 mg (i.m.) of estradiol cypionate (ECP), and P4 device withdrawal on day −2, followed by TAI on day 0 (n = 632 cows, being 409 primiparous and 223 multiparous; 300–2), 2) 300 IU (i.m) of eCG administered on days −4 and −2 (150 IU of eCG/day; n = 637 cows, being 412 primiparous and 225 multiparous; 300-4-2), 3) 400 IU (i.m.) of eCG administered on day −2 (n = 633 cows, being 406 primiparous and 227 multiparous; 400–2), and 4) 400 IU (i.m) of eCG administered on days −4 and −2 (200 IU of eCG/day; n = 634 cows, being 407 primiparous and 227 multiparous; 400-4-2). Individual cow BCS was assessed on days −11, 0 (timed-AI), and 31 of the study. Body condition score of the animals was classified into LOW or HIGH using the threshold of 2.75 (≤2.75 = LOW; >2.75 = HIGH). For primiparous cows, an eCG splitting effect was observed on follicle size, as cows receiving eCG on days −4 and −2 of the synchronization protocol had a larger follicle than cows administered eCG only on day −2. For day 31 P/AI, primiparous cows receiving 400-4-2, regardless of BCS, had a greater P/AI than cows from other treatments. Administering 400-4-2 to LOW BCS cows also resulted in greater P/AI than all other treatments assigned to LOW BCS cows. For multiparous cows, no treatment effect was observed for follicle size, estrus expression, and day 31 P/AI (P ≥ 0.21). In summary, increasing the dose and splitting the dose of eCG positively impacted the pregnancy rates of primiparous cows under a BCS ≤2.75, but no effects were detected on multiparous cows.

Rumen-protected methionine modulates body temperature and reduces the incidence of heat stress temperatures during the hottest hours of the day of grazing heat-stressed Bos indicus beef cows.

This study evaluated the effects of supplementation of rumen-protected methionine (RPM) on body thermoregulation and conception rate of Nelore cows exposed to high temperature-humidity index (THI). On -31 days before the artificial insemination protocol, 562 lactating, multiparous cows were assigned to receive (MG) or not (CG) RPM supplementation (3 g/cow mixed into 100 g of mineral supplement). Both groups remained in tropical pastures and received supplementation for 77 days. A subset of cows (n= 142) remained with an intravaginal thermometer collecting intravaginal temperature (IT). The respective minimum, average, and maximum environmental THI were 72.8, 78.0, and 83.3. Effects of treatment × hour of the day were detected (P< 0.0001) for IT. From 1330 to 1730 h and 1830 to 1900 h, IT was higher (P< 0.05) for CG versus MG cows when exposed to moderate and high THI. The supplementation with RPM did not affect conception rate (CG = 64.4% vs. MG = 58.2%; P> 0.05). In conclusion, 3g of RPM supplementation lowered internal body temperature and possibly altered critical THI threshold in Nelore cows with no impact on reproduction.

Macromineral in Nelore Cows of Different Ages from the Bolivian Tropics

Macromineral in Nelore Cows of Different Ages from the Bolivian Tropics

Effect of Different Herbage Allowances from Mid to Late Gestation on Nellore Cow Performance and Female Offspring Growth until Weaning.

This study evaluated different herbage allowances from mid to late pregnancy on pre- and postpartum physiological responses, milk production, and the performance of Nellore cows and the preweaning growth of their female offspring. Sixty multiparous Nellore cows were blocked by their body weight (BW; 425 ± 36 kg) and body condition score (BCS; 3.67 ± 0.23, scale 1-5) and randomly allocated to twelve pastures. Treatments consisted of two different herbage allowances (HA) during pregnancy: low HA (LHA; 2.80 kg DM/kg of BW) and high HA (HHA; 7.60 kg DM/kg of BW). Both treatment groups were fed 1 g/kg BW of a protein supplement. After calving, all cow-calf pairs were combined in a single group. The effects of maternal treatment × day of the study were detected for herbage mass and allowance, the stocking rate and forage crude protein, and for cow BW, BCS, and carcass measures (p < 0.01). Milk yield corrected to 4% fat, while the levels of fat total solids and cow plasma IGF-1 and urea were different (p ≤ 0.04) between treatments. HHA offspring was heavier (p ≤ 0.05) at 120 days and at weaning. A high herbage allowance can be implemented from mid-gestation until calving to increase cow prepartum performance, post-partum milk yield and composition, and positively modulate female offspring preweaning growth.

Efeito da suplementação com progesterona injetável de longa ação, sete dias após inseminação, sobre o desenvolvimento embrionário e fetal de fêmeas Nelore

ABSTRACT This study evaluated the effects of long-acting injectable progesterone supplementation (P4LA) on embryonic and fetal development and birth weight in Nellore cows seven days after timed artificial insemination (TAI). One hundred and nineteen Nellore female cows became pregnant after the TAI protocol and were divided into two groups: P4LA with cows that received 150mg of P4LA, seven days after insemination, in a single dose, and the control group, with cows who did not receive any hormonal supplementation after TAI. Blood samples were collected on days 17 and 30 after TAI to determine P4 concentration. Embryonic and fetal measurements were performed at 30 and 45 days of gestation, respectively, with the aid of ultrasonography, measuring craniocaudal length and thoracic diameter. No difference was observed in P4 concentration between the groups supplemented with or without injectable P4 on days 17 (P=0.73) and 30 (P=0.62) after TAI. There was no significant difference in embryonic and fetal development or birth weight between the supplemented and non-supplemented groups (P=0.59, P=0.09, and P=0.64, respectively). Supplementation with injectable progesterone seven days after TAI did not interfere with the embryonic and fetal development of Nellore cows, nor did it affect birth weight.

Effect of pregnancy and feeding level on voluntary intake, digestion, and microbial nitrogen synthesis in Zebu beef cows.

The objective of this research was to evaluate how pregnancy and feeding regimens affect the feed intake, digestibility, and efficiency of microbial nitrogen (N) synthesis in beef cows. Forty-four multiparous Nellore cows, comprising 32 gestating and 12 non-gestating cows, with an average weight of 451 ± 10kg, were assigned to either a HIGH (ad libitum) or LOW (limited feeding at 1.2 times maintenance based on the NRC) feeding regimen during the gestational period. The dry matter intake (DMI) in kg/d was significantly greater (P < 0.01) in HIGH-fed cows. The DMI reduced (P < 0.05) in proportion to the shrunk body weight (SBW) as days of pregnancy (DOP) increased. The interaction between feeding level and DOP was significant (P < 0.05) for the digestibility of dry matter (DM), organic matter (OM), N compounds, ether extract (EE), ash- and protein-free neutral detergent fiber (NDFap), gross energy (GE), and total digestible nutrients (TDN). Except for DM and TDN digestibility, there was a reduced nutrient digestibility as gestation progressed in HIGH-fed cows. In contrast, digestibility increased as a function of DOP in LOW-fed cows. Microbial N synthesis (g/day) was significantly higher in HIGH-fed cows (P < 0.001) compared to LOW-fed cows. The efficiency of microbial N production per g of N intake and kg of digestible OM intake was (P = 0.021) and tended (P = 0.051) to be greater in LOW-fed cows compared to HIGH-fed cows. In summary, HIGH-fed Nellore cows reduce feed intake and digestibility with advancing gestation, affecting feed utilization. In addition, LOW-fed cows, showed higher microbial protein synthesis efficiency, potentially making them more nutrient-efficient under challenging nutritional conditions.