In this study, we investigated whether decreased sensitivity to estradiol negative feedback is associated with reduced estrogen receptor α (ESR1) expression in kisspeptin neurons as ewe lambs approach puberty. Lambs were ovariectomized and received no implant (OVX) or an implant containing estradiol (OVX+E). In the middle arcuate nucleus (mARC), ESR1 messenger RNA (mRNA) was greater in OVX than OVX+E lambs but did not differ elsewhere. Post hoc analysis of luteinizing hormone (LH) secretion from OVX+E lambs revealed three patterns of LH pulsatility: low [1 to 2 pulses per 12 hours; low frequency (LF), n = 3], moderate [6 to 7 pulses per 12 hours; moderate frequency (MF), n = 6], and high [>10 pulses per 12 hours; high frequency (HF), n = 5]. The percentage of kisspeptin neurons containing ESR1 mRNA in the preoptic area did not differ among HF, MF, or LF groups. However, the percentage of kisspeptin neurons containing ESR1 mRNA in the mARC was greater in HF (57%) than in MF (36%) or LF (27%) lambs and did not differ from OVX (50%) lambs. A higher percentage of kisspeptin neurons contained ESR1 protein in all regions of the arcuate nucleus (ARC) in OVX compared with OVX+E lambs. There were no differences in ESR1 protein among the HF, MF, or LF groups in the preoptic area or ARC. Contrary to our hypothesis, increases in LH pulsatility were associated with enhanced ESR1 mRNA abundance in kisspeptin neurons in the ARC, and absence of estradiol increased the percentage of kisspeptin neurons containing ESR1 protein in the ARC. Therefore, changes in the expression of ESR1, particularly in kisspeptin neurons in the ARC, do not explain the pubertal escape from estradiol negative feedback in ewe lambs.
This study evaluated the effects of the mode of transportation on weight and metabolism of young bulls, which are generally transported by two systems: droving and truck. This experiment consisted of two phases: transportation and refeeding and involved transportation by droving and truck. Fifty young Nellore bulls were separated in equal numbers in both groups, droving group and truck group. In the transportation phase, animals were moved, in a 640-km journey. The refeeding phase consisted of 84 days and commenced after the animals arrived at the fattening farm. The effect of the transportation system on animals' weight, metabolic hormones, and serum biochemistry was assessed after 28, 56, and 84 days. During the transportation phase, animals in the droving group lost 10.11 kg and animals in the truck group gained 13.1 kg. The truck group showed 20.5 kg of weight gain at the end of the refeeding phase. The highest triiodothyronine (T3) and thyroxine (T4) concentrations were observed on days 0 and 60 in the transportation phase in both droving and truck groups. The serum cortisol concentration was higher in the droving group than in the truck group on day 56 of the refeeding phase. The IGF-I concentrations were higher during the refeeding phase in the droving group than in the truck group. Our results showed that transportation by droving leads to increased weight loss and reduced further weight gain compared to transportation by truck and that serum concentrations of T4, cortisol, and insulin-like growth factor (IGF-I) hormones are altered by the transportation system.
The use of different types of concentrated supplements on the performance of Nellore calves grazing Urochloa brizantha cv. Marandu in the dry season was evaluated. The experiment was conducted on 24 ha divided into 12 paddocks. Seventy-two calves with initial body weight (BW) 176±14kg for 140 days of experiment were used. Evaluated treatments included: Mineral, Salt+urea (mineral with 30% urea), Protein (supplementation with 45% crude protein (CP) and 46% total digestible nutrients (TDN)); and Protein+energy (with 28% CP and 73% TDN). The Mineral, Salt+urea, and Protein were offered ad libitum, and the Protein+energy 5g/kg BW. Protein+energy showed the highest (P< 0.05) intake (3.66g/kg BW) followed by the Protein (1.61), Salt+urea (0.36), and Mineral (0.32). The two latter supplements were not significantly different (P> 0.05). The highest (P< 0.05) average daily gain (ADG, kg/day) was observed in the Protein+energy (0.074). Average daily gains for the Protein and Salt+urea (0.014 and -0.024, respectively) were not significantly different (P> 0.05), but were significantly higher (P< 0.05) than the Mineral (-0.085). Therefore, during the dry season, to prevent the loss of bovine weight the supplements must supply in addition to minerals, also energy, non-protein nitrogen (NNP), and true protein.
With the objective to evaluate different frequencies of supplementation on the performance and ingestive behavior of Nellore calves kept on Urochloa brizantha cv. Marandu pasture, 56 animals with initial average body weight (BW) of 174.5 kg were submitted to the following treatments: no supplement and 1x, 3x, and 7x supplementation per week. The supplement was provided in the amount of 3.5 g kg-1 of BW day-1. BW and evaluation of behavior were assessed every 28 days. The randomized block's design with two repetitions was used. The analyses of variance were carried out by the GLM procedure in the SAS software, and the means were compared by the Tukey’s test at 5% significance. The supplementation increased the average daily gain (ADG; P ? 0.05); however, it did not differ between frequencies (0.005, 0.190, 0.183, and 0.177 kg head-1 day for the no supplement treatment and 1x, 3x, and 7x per week, respectively). The animals in the no supplement treatment showed longer grazing time (P ? 0.05) compared to those receiving the supplement. However, results did not differ between frequencies (10.44, 8.57, 8.32, and 8.59 hours day-1 for no supplement treatments and 1x, 3x, and 7x per week, respectively). Thus, the frequency of supplementation can be reduced to once a week without reducing animal performance.
The objective of this study was to evaluate the effects of a synthetic analogue of the bovine appeasing pheromone (i.e. bovine appeasing substance; BAS) on growth and temperament of weaned calves grazing Capim-Marandú (Urochloa brizantha cv Marandú). At weaning (d 0), 86 calves (47 steers and 39 heifers; Aberdeen Angus ′ Nelore; 8 ± 1 mo) were stratified by body weight (197.9 ± 24.9 kg) and randomly assigned to receive a single dose of BAS (n = 43; SecureCattle; Nutricorp, Araras, SP, Brazil) or saline (CON; n = 43; saline 0.9% NaCl). Treatments (5 ml) were topically applied to the nuchal skin area of each animal on d0. Body weight was collected on d 0, 8, 15, 51 and 100. Chute score (1 to 5; 1 = calm, no movement; 5 = violent and continuous struggling) and chute entrance and exit scores (1 to 3; 1 = slow; 3 = fast) were collected on d 3, 8, 15, 51 and 100. Scores were averaged across 3 trained technicians. Data were analyzed using the MIXED procedure of SAS. Calves assigned to BAS treatment had greater (P < 0.01) average daily gain (ADG) from d 8 to 15 (0.158 and -0.284 kg/d ± 0.07). Calves assigned to BAS treatment tended (P = 0.10) to have lower chute entrance score on d 8 and 51 and had lower (P = 0.02) chute exit score on d 8 than calves assigned to CON treatment. Additionally, calves assigned to BAS treatment tended (P = 0.07) to have lower chute score on d 8 when compared to calves assigned to CON treatment. The application of BAS at weaning improved calf ADG and improved calf temperament as observed by chute score and chute entrance and exit scores, suggesting that BAS application has calming effects.
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