This work was carried out to evaluate the effect of soya and linseed on the chemical composition and fatty acid profi le of the Longissimus muscle of crossbred bulls fi nished in feedlot. Twenty-one crossbred bulls (1/2 Nelore vs 1/2 Simmenthal), at an average age of 18 months were used in a completely randomized design, with three treatments and seven repetitions. The dietary treatments were: control (CON), linseed and soyabean (SOYA), and soyabean and linseed added after the 60 th day of the experiment (LIN). No difference (P>0.05) was observed among the treatments on the chemical composition of the Longissimus muscle. The values of conjugated linoleic acid (18:2-c-9, t-11) were higher (P<0.05) in the LIN (0.39%) and SOYA (0.46%) treatment, as compared with the CON treatment (0.26%). n-3 PUFA values were higher (P<0.05) in the LIN treatment (1.58%) as compared with the CON treatment (0.83%).

In beef cattle production under pasture-based tropical conditions, the minerals most likely to be lacking are Ca, P, Na, Co, Cu, I, Se, and Zn, all of which are required for optimal growth and reproduction. Phosphorous deficiency, in particular, is a major problem for grazing cattle in many tropical regions. On the other hand, reproductive infectious diseases are the greatest threat to the production and profitability of beef cattle herds. To overcome reproductive failure, the present study aimed to evaluate the effects of injectable mineral supplementation and vaccination against reproductive diseases on synchronised Nelore females for fixed-time AI. A total of 1361 females were enrolled, and blood was collected from a random population (n=150) to measure serum antibodies against Leptospira sp., infectious bovine rhinotracheitis, and bovine viral diarrhea, mineral status, and creatinine. With Day 0 as the beginning of the synchronisation programme and Day 10 as the day of fixed-time AI, females were randomly assigned as follows. In the control treatment (n=365), no additional treatment was administered. In the Vaccine treatment (n=314), at Days −21 and 0 females received a 5-mL subcutaneous injection of BovigenRepro (Virbac; inactivated vaccine containing infectious bovine rhinotracheitis 1 and 5; bovine viral diarrhea 1 and 2; Campylobacter fetus ssp. fetus, venerealis, and venerealis biotype intermedius; and Leptospira pomona, wolffi, hardjo prajitno, icterohaemorrhagiae, canicola, copenhageni, bratislava, and hardjo bovis in an adjuvant of 10% Al(OH)3 with Se). In the Suppl treatment (n=314), at Day 0 females received a 15-mL intramuscular injection of Fosfosal (Virbac; 100mL containing Na glycerophosphate (14g), monosodium phosphate (20.1g), copper chloride (0.4g), potassium chloride (0.6g), magnesium chloride (2.5g), and sodium selenite (0.24g). In the SupplVacc treatment (n=363), females received a 5-mL subcutaneous injection of the vaccine at Days −21 and 0 as well as a 5-mL intramuscular injection of Fosfosal at Day 0. Pregnancy was verified by transrectal ultrasound at Days 40 and 100. Body condition score was recorded on Days −21 and 40. Data were analysed using the GLIMMIX procedure of SAS (SAS University edition, SAS Institute Inc.). When significant, Tukey and least squares means tests were used to compare means. Serum analysis showed that 89% of the animals had seroprevalence to at least two diseases. Average blood P concentration was 7.2mg dL−1. Pregnancy was affected by Ca levels (pregnant=2.55mg dL−1; non-pregnant=2.33mg dL−1; P&lt;0.05) and creatinine levels (pregnant=5.85mg dL−1; non-pregnant=5.76mg dL−1; P&lt;0.05). The average BCS was 3.2 (1=skinny; 5=fat), and there was no effect of time (Days −21 to 40). Pregnancy verified by transrectal ultrasound at Day 40 for the Vaccine, Suppl, SupplVacc, and control treatments was 54, 52, 57, and 49% (P=0.11), respectively. There was a tendency of higher pregnancy verified by transrectal ultrasound at Day 90 for the SupplVacc group (55%) compared with the control group (45%; P&lt;0.1). There was no effect of pregnancy loss among groups that were vaccinated (control=6%, vaccine=5%, Suppl=4%, and SupplVacc=3%). Considering only pluriparous cows, there was an increase in pregnancy per AI in the SupplVacc group (59%) compared with the control group (51%; P&lt;0.05). Once females presented a very good BCS, the supplement effect was only an immunostimulant. Starting a breeding season with supplementation and vaccination can increase pregnancy rate and profitability for farmers.