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Context Integrated crop–livestock–forestry systems can be an alternative to monoculture pastures; however, the effect of the arboreal component on tillering and tussock dynamics of understorey grass canopy is not well understood. Aims Our objective was to evaluate the patterns of tillering dynamics, population stability and tussock distribution of Piatã palisadegrass (Urochloa brizantha) as affected by contrasting shading regimes in the Brazilian Amazon biome. Methods The following three shading regimes were assessed: pasture with no trees (no shading, NS), moderate shading (MS, 338 trees ha−1), and intense shading (IS, 714 trees ha−1). Pastures were rotationally grazed by dairy heifers. Paddocks from MS and IS were stratified into three sampling strips, including two closer to the tree rows (i.e. lateral) and one between the two lateral strips (i.e. central). Two methods for monitoring sward canopy light interception (LI) were used for IS regime, namely, LI taken under the tree canopy (i.e. inside) and LI was taken above the tree canopy (i.e. outside). Key results Relative to NS, there was a reduction in photosynthetically active radiation transmittance of 18.1% and 37.1% on MS and 49.9% and 52.0% on IS for central and lateral shading strips respectively. Overall, the increase in shading level was associated with a decrease in average tussock perimeter, tiller population density, and an increase in the frequency of bare ground. Conclusions Our findings clearly indicate the key role of the light environment as a determinant of Piatã palisadegrass horizontal structure. Implications It highlights the importance of planning the levels of tree density and layout in areas of crop–livestock–forestry integration.

Context Reproductive technologies may either contribute to the increase of genetic gains or inbreeding levels in dairy cattle breeding programs and herds. In general, studies have evaluated the impacts of inbreeding on traditional traits, such as production and reproduction. However, studies on novel traits, such as milk fatty acids profile, are scarce in the literature. Aim We aimed to evaluate the impact of inbreeding levels on milk fatty acids profile measured in a Brazilian Holstein cattle population. Methods Monthly records of the percentages (%) of palmitic, stearic, oleic, total saturated, unsaturated, monounsaturated and polyunsaturated fatty acids in milk were collected from 2047 Holstein cows between May and December 2012. The pedigree file contained 7963 animals over seven generations. The inbreeding trend was evaluated by linear regression of inbreeding coefficients on generations. The inbreeding impacts on breeding and phenotypic values were evaluated by linear regression of breeding values and phenotypic values on generations respectively. Breeding values were obtained by a Bayesian approach based on an animal model that included the systematic effect of contemporary group, cubic effect of days in milk as a covariate, and the random direct additive genetic and animal permanent environmental effects. Key results The average inbreeding coefficient was 0.28% for all animals, and 1.39% for inbred animals. Inbreeding tended to increase 0.24% per generation (P-value 0.18, 0.10, 0.16, 0.26, 0.51 and 0.09 respectively); whereas for polyunsaturated fatty acids, they were significant (P-value 0.33, 0.78, 0.48, 0.32 and 0.07 respectively). However, they were significant for saturated and palmitic fatty acids (P-values

This study evaluated the use of cooled semen in a fixed-time artificial insemination (FTAI) program compared with frozen–thawed semen to improve pregnancy rates in beef cattle. Ejaculates of three bulls were collected and divided into two treatments: (1) frozen–thawed semen and (2) cooled semen. Egg-yolk extender without glycerol was used for the cooled semen treatment. Straws (25 × 106 spermatozoa) were submitted to cooling for preservation at 5°C for 24 h, after which FTAI was performed. Nelore cows (n = 838) submitted to FTAI were randomly inseminated using frozen–thawed semen or cooled semen. There was a 20% increase in the pregnancy per AI (P AI–1) using cooled semen compared with frozen–thawed semen (59.9 ± 4.7 vs 49.4 ± 5.0%; P 0.05). Because there was less damage to spermatozoa and improvement in P AI–1, the use of cooled semen instead of frozen–thawed semen is an interesting approach to increase reproductive efficiency in cattle submitted to a FTAI protocol.

Testosterone metabolism occurs primarily in the liver, and circulating concentrations can be influenced by the amount and type of diet provided. Furthermore, there are reports of the influence of circadian rhythms on secretion of testosterone in ruminants. Based on evidence that supplementation with rumen-protected fat may increase circulating concentrations of steroid hormones (Guardieiro et al. 2010 Pesq. Agrop. Bras. 45, 408–414), this study aimed to evaluate the effect of the addition of rumen-protected fat, antioxidants, or both to the diet on serum testosterone concentration in bulls, and to assess whether there is variation in hormone concentrations at different times of the day after feeding. Forty-eight Nelore bulls were confined and assigned to four treatment groups according to the addition of rumen-protected fat, antioxidants, or both to the standard diet (sugarcane bagasse, citrus pulp, corn gluten meal, urea, and mineral salt): F) rumen-protected polyunsaturated fatty acids [PUFA; rich in linoleic, Megalac E®, QGN-Arm & Hammer, Rio de Janeiro, Brazil; 1.5% on dry matter (DM); n = 12]; A) antioxidant (a source of vitamin C and selenium, EconomasE®, Alltech Biotechnology, Buenos Aires, Argentina; 3 g/head/d; n = 12); FA) Megalac E® and EconomasE® (n = 12), or C) nothing (Control group; n = 12). After 75 days of offering diets, jugular blood samples were collected just before IV injections that were performed three times a day (7:00, 13:00, and 19:00 h) with saline (Control group, n = 24) or gonadotropin-releasing hormone (GnRH; 50 μg Gonadorelin, Fertagyl, MSD Saúde Animal, São Paulo, Brazil; GnRH group, n = 48) and 2 h afterward. Bulls were fed 1 h after the first IV GnRH/saline and the diets remained in the bunk for 17 h. Serum testosterone concentrations were measured by radioimmunoassay. Data were analysed by repeated-measures of GLIMMIX of SAS (SAS Institute Inc., Cary, NC, USA). As expected, the GnRH injections increased concentrations of testosterone after 2 h compared to saline (5.4 ± 0.16 v. 3.2 ± 0.16 ng mL–1; P

The present study evaluated superovulatory responses and in vivo embryo production in cows treated with FSH starting 1 or 2 days after ovum pick-up (OPU). Thirty-three non-lactating Nelore cows were subjected to aspiration of all follicles ≥3 mm for OPU. After OPU, cows were randomly divided into two groups in which the follicle superstimulatory treatments with FSH started 1 or 2 days after OPU (Groups D1 and D2, respectively). Data are presented as the least squares mean ± s.e.m. The number of follicles ≥3 mm before OPU was similar between groups (~34); however, cows in Group D2 had more follicles ≥3 mm on the first day of FSH (15.2 ± 2.3 vs 7.6 ± 1.7; P = 0.04) and a higher ratio of the number of follicles at first FSH/number of follicles before OPU (0.41 ± 0.04 vs 0.24 ± 0.02; P = 0.01). In addition, Group D2 cows had a greater superovulatory response than did cows in Group D1 (18.9 ± 2.8 vs 9.1 ± 1.9 corpora lutea, respectively; P 0.10). Nevertheless Group D2 cows had more freezable embryos than Group D1 cows (3.2 ± 1.1 vs 1.3 ± 0.5, respectively; P

The aim of this study was to evaluate the influence of high or low dry matter (DM) intake and/or energy on embryo quality and production in vivo. Nonlactating Nelore cows (n = 32, 4 to 10 years old) weighing 489.5 ± 11.3 kg and with a body condition score of 3.25 (1 to 5) were used. After 15 days on the adaptation diet, cows were blocked by initial body weight (BW) and randomly divided in 4 experimental groups. The maintenance group (M) received a diet to provide 1.2% of DM/kg of BW. The restriction group (0.7M) received the equivalent of 70% of the group M diet (0.84% of DM per kg of BW). The high intake group (1.5M) received the equivalent of 150% of the M group (1.8% of DM/kg of BW). The energy group (E) received a diet with a DM similar to the M group but with an energy level equivalent to the 1.5 M group. All cows were submitted to aspiration of follicles >2 mm for ovum pick-up (OPU). Recovered oocytes were used in another experiment. The embryo donors received an intravaginal device (IVD) of progesterone release (Sincrogest®, Ouro Fino, Ribeirão Preto, Brazil), soon after OPU. Two days after OPU, the cows received 8 decreasing doses of FSH (100 mg, IM, Folltropin-V®, Bioniche Animal Health, Belleville, Ontario, Canada) and concomitant with the fifth and sixth treatments of FSH, PGF2α (500 μg each, IM, cloprostenol, Sincrocio®, Ouro Fino) was administered. The IVD was removed at the time of the last FSH injection. Twelve hours after IVD removal ovulation was induced with GnRH (0.01 mg, IM, Buserelin acetate, Sincroforte®, Ouro Fino). Cows were inseminated 12 and 24 h later. Embryo collection was performed 7 or 8 days after GnRH injection. The cows were offered all diets in a crossover design study. There were 4 sessions of embryos flushing, each 42 days apart. Data were analysed by PROC GLIMMIX of SAS (SAS Institute Inc., Cary, NC, USA) and the results are presented as least-squares means ± SE, always following the order of treatments 0.7 M, M, 1.5 M and E. There were differences in the superstimulatory response (12.6 ± 1.4b; 14.6 ± 1.6a; 13.6 ± 1.5ab; and 11.0 ± 1.2c follicles >6 mm; P

Recent studies that have used eCG administration either 14 or 22 days after fixed-time AI in dairy and beef cattle have indicated a positive effect on conception rates. The aim of this study was to evaluate conception rates in embryo recipients treated with eCG 7 days after fixed-time embryo transfer (ET). A protocol for synchronization of ovulation was used in 470 Nelore and crossbred embryo recipient heifers (n = 179), dry cows (n = 152), and lactating cows (n = 139; body condition score = 3.0 to 3.5; >40 days in milk). All heifers and dry cows, but only 27.3% of lactating cows, were cycling at the beginning of the synchronization protocol. On Day 0, each female received IM injections of 2 mg of oestradiol benzoate (Gonadiol, Intervet Schering-Plough Animal Health, São Paulo, Brazil) and 0.075 mg of PGF2α (Preloban, Intervet Schering-Plough Animal Health). An intravaginal progesterone-releasing device (DIB, Intervet Schering-Plough Animal Health) was also inserted on Day 0. On Day 8, the DIB device was removed and cows or heifers received another IM treatment of 0.075 mg of PGF2α (Preloban), 300 IU of eCG (Novormon, Syntex S.A., Buenos Aires, Argentina) and 0.6 mg of oestradiol cipionate (Pfizer, Brazil). Transrectal ultrasonography was performed in all recipients on the day of ET (Day 16, 17, or 18 of the protocol) and only those with a corpus luteum greater than 15 mm in diameter were selected (n = 113 heifers, 114 dry cows, and 70 lactating cows). Transfers of fresh, frozen, and vitrified in vivo-produced embryos from Nelore donors were balanced between experimental groups. Seven days after ET, 127 animals received an IM injection of 400 IU of eCG (eCG group), and the 170 remaining cows or heifers were not treated with eCG, and were therefore considered the control group. Pregnancy diagnosis was performed 30 and 60 days after ovulation by transrectal ultrasound. Data were analysed using generalized linear models and results are presented as least squares means ± standard error. Conception rates were similar in the eCG and control groups at Day 30 (35.9 ± 5.5 and 33.5 ± 4.4, respectively; P > 0.10) and at Day 60 (27.6 ± 4.9 and 26.7 ± 3.9, respectively; P > 0.10). Contrary to other results in the literature, especially in dairy cows bred by fixed-time AI, the use of eCG 7 days after ET did not improve conception rates in Bos indicus cattle used as embryo recipients. Financial support from CNPq, FAPESP, and Intervet Schering-Plough Animal Health of Brazil and Syntex S.A. of Argentina.

Polyunsaturated fatty acids seem to exert an extra-caloric positive effect on ruminant reproduction, although the reasons for that are still unclear. Although some studies have detected a positive effect of feeding unsaturated fatty acids on embryo development of superovulated Bos taurus cattle (Thangavelu et al. 2007 Theriogenology 68, 949-957), others have not (Petit et al. 2008 J. Dairy Sci. 91, 1786-1790). Our hypothesis was that, although number and quality of embryos from superovulated heifers would not be affected by diet, supplemental fat would improve embryo cryotolerance. Therefore, this study evaluated superovulatory response and embryo production, as well as cryotolerance of embryos cryopreserved through freezing or vitrification in Nellore heifers supplemented with rumen-protected fat. Forty heifers (24 to 36 mo old) were kept in pasture and randomly divided into 2 experimental groups according to supplemental source [F = concentrate with rumen-protected fat (100 g/d of Megalac-E®) and C = control, without fat supplementation]. Supplements were formulated to be isocaloric and isoproteic. Each female underwent both treatments in a cross-over design with approximately 68 d between replicates. After 50 d of feeding, emergence of the wave was synchronized with the aid of hormones to initiate the superovulation protocol. Recovered embryos were frozen or vitrified, and subsequently in vitro embryo development evaluation was accomplished. Data were analyzed using generalized linear models. There was no difference between F and C groups (P > 0.10) regarding superstimulatory response, number of total embryos/ova, viable embryos, degenerate embryos, or unfertilized oocytes recovered. However, group C had a greater superovulatory response than F (18.0 ± 1.3 v. 15.7 ± 1.2 CL; P = 0.06). Group C embryos presented greater hatching rate, independently of the cryopreservation method, at 48 h (33.1 ± 4.0%; n = 148 v. 17.3 ± 3.3%; n = 137; P = 0.009) and at 72 h (44.3 ± 4.2%; n = 148 v. 30.9 ± 4.0%; n = 137; P = 0.04) of in vitro culture. Under the conditions of the present study, supplementation with protected fat did not affect superstimulatory response and quantity or quality of embryos. However embryos from the F group were less tolerant to cryopreservation. Financial support from FAPESP, EMBRAPA, Arm & Hammer, Integral Produbon, and Pfizer of Brazil.

Results from a previous experiment (Barros C et al. 2008 Reprod. Fertil. Dev. 20, 152 abst) have shown that the replacement of porcine FSH (pFHS) by eCG on the last day of the superstimulatory treatment in Nellore (Bos indicus) cows resulted in a greater superovulatory (SOV) response as compared with treatment exclusively with pFSH. However, another study (Sartori R et al. 2009 Reprod. Fertil. Dev. 21, 245-246 abst) in Nellore heifers did not corroborate those observations. The aim of this study was to evaluate the SOV response of Sindi (Bos indicus) donors submitted to this protocol. Forty-eight SOV treatments were performed in a crossover design in 19 nulliparous and primiparous females that were randomly divided into 2 groups: FSH (n = 24), which consisted of 8 pFSH injections (Folltropin®-V, Bioniche Animal Health; Belleville, Ontario, Canada), or FSH-eCG (n = 24), which consisted of 6 pFSH injections followed by 2 eCG injections (Folligon®, Intervet Schering-Plough Animal Health, Brazil). Each female underwent 2 or 3 SOV treatments that consisted of an i.m. injection of 2 mg of estradiol benzoate (Gonadiol®, Intervet) and the insertion of an intravaginal progesterone-releasing device (DIB®, Intervet) on Day 0. On Day 4, the superstimulatory treatments (100 or 150 mg of pFSH, based on previous history of SOV responses) were initiated and given in decreasing doses twice a day over a 4-day period. In the FSH-eCG group, the last 2 doses of pFSH were replaced by 2 doses of eCG (150 or 200 IU of eCG each). At the time of the fifth and sixth injections of FSH, 0.150 mg of PGF2 (Preloban®, Intervet) was injected i.m. The DIB® device was removed at the time of the last FSH or eCG injection and ovulation was induced with 0.2 mg of GnRH (Fertagyl®, Intervet) 12 h later. All females were artificially inseminated with frozen-thawed semen from the same bull 12 and 24 h after GnRH treatment. Seven days after the first AI, embryos/ova were recovered. Superstimulatory (number of follicles ≥6 mm at the time of the last FSH or eCG injection) and SOV (CL number) responses were determined by transrectal ultrasonography. Data were analyzed using generalized linear models and results were presented as least squares means ± standard error. The FSH-eCG group had higher superstimulatory (33.3 ± 3.9 v. 24.2 ± 3.0 follicles; P ≤0.06) and SOV (16.8 ± 2.9 v. 10.8 ± 2.1 CL; P ≤ 0.10) responses. Although the number of total ova/embryos recovered was not different between groups (8.2 ± 1.8 v. 5.9 ± 1.4 for FSH-eCG and FSH groups, respectively; P > 0.25), the number (6.5 ± 1.2 v. 2.4 ± 0.7; P ≤ 0.008) and percentage (75.2 ± 6.6 v. 52.8 ± 8.6%; P ≤ 0.05) of viable embryos was greater for the FSH-eCG females. Contrasting with the results in Nellore heifers, this study observed improvement in superstimulatory and SOV responses and embryo quality by replacing the last 2 doses of pFSH by eCG in Sindi donors. Financial support from FAPESP, EMBRAPA, Intervet Schering-Plough Animal Health, Nutricell, and Sindi do ACS of Brazil.

Several studies using sex-sorted sperm by flow cytometry have shown that its fertility is reduced. Therefore, this study evaluated structural and functional characteristics of sperm sexed by flow cytometry. In addition, in vitro embryo production (IVP) and development was assessed when frozen-thawed unsorted and sex-sorted sperm from 4 Nellore bulls. Each ejaculate was separated into three fractions: non-sexed (NS), sexed for X-sperm (SX), and sexed for Y-sperm (SY). After thawing, each sample was analyzed for sperm motility by computer-assisted semen analysis (CASA, Berkeley, CA), sperm head agglutination, sperm morphology, membrane integrity by propidium iodide (PI) and 6-carboxy-fluorescein diacetate (CFDA) staining, acrosome integrity by peanut agglutinin (PNA), capacitation by chlortetracycline (CTC), and chromatin integrity by acridine orange staining. Then, the samples were placed in 45 : 90% (NS90) or 45 : 60% (NS60, SX, and SY) Percoll™ gradients. After Percoll™ centrifugation, sperm pellets were analyzed or used for IVP. All analyses were replicated independently three times. For IVP, 2,271 in vitro matured oocytes were used. To assess fertilization rate, presumptive zygotes were fixed and stained with lacmoid at 18 h post-insemination (hpi). Cleavage was evaluated at Day 2 (48 hpi) and blastocyst development at Days 6, 7, 8, and 9 of culture. Data were analyzed using generalized linear models. No differences (P > 0.05) were observed between SX and SY groups for e sperm variables evaluated either before or after Percoll™. However, non-sexed sperm had higher sperm motility, greater percentage of sperm with intact membranes, and greater percentage of live sperm with intact acrosomes than sexed sperm (P < 0.05). An effect of Percoll™ was observed in the non-sexed samples, with those submitted to 45 : 90% gradient having higher motility, greater percentage of cells with intact membrane, and lower recovery rate than those submitted to a 45 : 60% gradient. No differences among groups were observed for fertilization rate, being 74.0 ± 5.7, 63.2 ± 5.1, 67.2 ± 5.7, and 55.4 ± 5.9% for NS90, NS60, SX, and SY, respectively. Group NS90 showed a greater cleavage rate than did the SY group, while groups NS60 and SX had similar rates to the others. Blastocyst development rates on Day 6 to Day 9 were greater for group NS90. For example, on Day 8 the blastocyst rate was 34.9 ± 3.6, 22.2 ± 3.2, 18.1 ± 3.3, and 14.8 ± 2.9% forNS90, NS60, SX, and SY groups, respectively. All groups showed similar embryonic developmental stages on Day 6 to Day 9. Although sex-sorting affected sperm characteristics, it did not cause a decrease with in vitro fertility. However, differences in blastocyst rates between groups NS60 and NS90 indicated that the sperm selection protocol affected embryo production. Financial support: Embrapa Genetic Resources and Biotechnology.