João Batista Souza Borges

Bioeconomic impact of bull breeding soundness examination in cow-calf systems

Avaliou-se o impacto bioeconomico do exame andrologico na producao de bovinos de corte no Sul do Brasil. Foram comparados dois sistemas de producao similares com e sem a adocao do exame andrologico durante quatro anos no municipio de Julio e Castilhos. A taxa de touros inaptos no primeiro exame foi de 22,8%. Com a realizacao do exame, obteve-se aumento de 31% na producao de bezerros, 13,8 bezerros/touro/ano e 24 kg de bezerros/vaca/ano. A relacao beneficio/custo sobre o investimento com o exame andrologico foi de R

Measurement of scrotal circumference in beef bulls in Rio Grande do Sul

35,84. O exame andrologico melhora os aspectos bioeconomicos de sistemas de cria de bovinos de corte.It was evaluated the bioeconomic impact of the breeding soundness evaluation on beef cattle production in southern Brazil. Two similar production systems, with and without the use of breeding soundness evaluation, were compared during 4 years in the municipality of Julio e Castilhos. The rate of unsound bulls in the first examination was 22.8%. By performing the examination, calf production increased by 31%, 13.8 calves/bull/year and 24 kg of calves/cow/year. The benefit/cost ratio on the investment with the breeding soundness evaluation was R

Indução da atividade cíclica ovariana pós-parto em vacas de corte submetidas à interrupção temporária do aleitamento associada ou não ao tratamento com norgestomet-estradiol

35.84. The breeding soundness evaluation improves bioeconomic aspects of beef cow-calf systems.

Causes of rejection of beef bulls in breeding soundness evaluation

The variability of scrotal circumference and the effects of age and breed as well as the relationship between testicular weight (TW), scrotal circumference (SC), and live weight (BW) were investigated in bulls. Devon, Polled Hereford, and Red Angus breeds showed higher SC values than the other British, Continental, Synthetic, and Zebu studied breeds. The percentage of culled bulls because of low SC ranged from 7.01 to 24.25%. The increase of SC was proportional to the increase in TW and they were highly correlated (r2= 0.90). The results suggest that SC in young bulls is the best way to predict TW and, therefore, a useful tool for their selection

Optimizing timed AI protocols for Angus beef heifers: Comparison of induction of synchronized ovulation with estradiol cypionate or GnRH

The present study aims to compare the effects of removing the calf for 72 hours associated or not with Norgestomet (NOR) implant and estradiol upon estrus induction and fertility in postpartum aciclic beef cows. The temporary weaning (DT) group (n=38) was separated from their calves for 72 hours The NOR group (n= 29) received on Day 0 a 3mg Norgestomet implant subcutaneously and 5 mg of estradiol valerate, and 3mg of Norgestomet intramuscular. On Day 9 the implants were removed and the calves were separated for 72 hours. The interval from weaning to estrous was significantly shorter (P<0.05) for cows treated with progestogens (50.1 hours) compared with calf removal group (86.4 hours). The estrous induction rate was significantly higher (P<0.05) for Norgestomet and estradiol treated cows, but ovulation rate, first pregnancy rate and at the end of the breeding season were similar for both groups. The Norgestomet and estradiol treatment of aciclic beef cows improved the estrous incidence after 72 hours tempory weaning. The results demonstrate that the treatment of aciclic beef cows with Norgestomet and estradiol increases the induction of estrous after 72 hours of temporary weaning, without interfering with the pregnancy rates of first estrous and in the reproductive season.

12 OVARIAN STRUCTURES, ESTRUS EXPRESSION, AND PREGNANCY RATE IN BEEF HEIFERS USING ESTRADIOL CYPIONATE OR GnRH AS OVULATION INDUCTORS IN TIMED AI PROTOCOL

The objective of this study was to analyze the rates of rejection in the different steps of the breeding soundness evaluation of beef bulls in the state of Rio Grande do Sul, Brazil. The breeding soundness of 22,113 young and mature bulls of 14 beef breeds, participating in the Program of Reproductive Evaluation (PARTO) was evaluated in the experiment. Data concerning to the causes of rejection in the four steps of the breeding soundness evaluation (general physical examination, genital tract examination, semen evaluation and sexual behavior assessment) were analyzed by the Chi-square test and univariate regression analysis. According to year, general physical examination, genital tract examination and semen evaluation determined the rejection of 0.9% to 2.5%, 5.1% to 7.7%, 1.8% to 5.3%; and 4.2% to 6.7%, 7.3 to 9.3%, and 2.5% to 5.5% of young and mature bulls, respectively. Mature bulls presented higher chances of rejection than young bulls in the general physical examination in every year evaluated; as to the genital tract examination, their chances of rejection were higher in years I and II, but not in year III. In the semen evaluation, there was no difference between the ages assessed in any of the three years evaluated. Sexual behavior assessment accounted for the rejection of 1.9 to 6.0% of the young bulls and 2.9% to 3.9% of mature bulls, in accordance with the years evaluated; in years I and II, mature bulls presented higher rejection rates than young bulls. These results confirm the importance of performing all steps of the breeding soundness evaluation, including the sexual behavior assessment as a work routine, rather than an additional, optional stage of the evaluation, which should be carried out before the breeding season. The results indicate the relationship between bull age and rejection rate in the breeding soundness evaluation.

Ganho de peso na recria e desempenho reprodutivo de novilhas acasaladas com sobreano

This study compared estradiol cypionate (ECP) or GnRH as ovulation inducers at the end of a timed AI (TAI) protocol in Angus heifers. On day 0, heifers (n = 415), between 22 and 24 months of age, were treated with an intravaginal 1 g progesterone (P4) insert and 2 mg of estradiol benzoate. On day 8, heifers had P4 removed, received 500 μg cloprostenol, and were randomized into two groups: ECP [n = 214; 0.5 mg of ECP on day 8] or GnRH [n = 201; 25 μg of GnRH analog licerelin acetate on day 10]. All heifers received TAI on day 10; 48-50 h after P4 insert withdrawal. Estrus was determined by removal of tail paint. Ovaries of heifers were evaluated by ultrasound on day 0 to determine CL presence (with CL = 213, without CL = 202) and on day 10 to measure preovulatory follicle size. Heifers were divided into three categories based on preovulatory follicle diameter: <8.5 mm (smaller than deviation), 8.5-10.9 mm, or ≥11 mm. Pregnancy diagnosis was performed 32 days after TAI. Heifers treated with ECP had greater expression of estrus than GnRH-treated heifers (93.9% vs 67.7%; P < 0.0001), regardless of CL presence at beginning of protocol. Heifers with CL at beginning of protocol had larger preovulatory follicle diameter (10.4 mm vs 9.6 mm; P = 0.0058) and greater pregnancy per AI (P/AI; 61.0% vs 50.5%; P = 0.032) than heifers without CL at day 0. In heifers with CL at day 0, GnRH treatment increased P/AI compared to ECP treatment (68.0% vs 54.9%; P = 0.0498). Expression of estrus was greater in ECP-treated than GnRH-treated heifers that had small (<8.5 mm; 77.1% vs 5.6%; P < 0.001) or medium-sized (8.5-10.9 mm; 98.4% vs. 61.7%) follicles, but not in heifers with large follicles (≥11 mm; 97.9% vs 98.3%). The P/AI was very low in both treatments for heifers with follicles <8.5 mm (ECP-14.3% vs GnRH-16.7%). In heifers with medium-sized follicles (8.5-10.9 mm), ECP treatment tended to increase P/AI compared with GnRH-treated heifers (62.9 vs 46.7%; P = 0.074). In contrast, P/AI was greater for GnRH-treated than ECP-treated heifers with large preovulatory follicles (≥11 mm; 79.7% vs 60.4%; P = 0.032). Thus, the optimal inducer of ovulation in a TAI protocol for beef heifers appears to depend on the presence of a CL at beginning of protocol (GnRH > ECP if CL present) and size of the preovulatory follicle, with ECP increasing expression of estrus and tending to increase fertility in heifers with medium-sized follicles but GnRH increasing fertility in heifers having large preovulatory follicles.

Histopathological, immunohistochemical and biomolecular diagnosis of myocarditis due to Clostridium chauvoei in a bovine

The aim of this study was to evaluate the effect of presence of corpus luteum (CL) at the onset of timed AI (TAI) protocol, size of ovulatory follicle and oestrus expression on pregnancy rate using E2 cypionate (EC) or GnRH as ovulation inductor in Angus heifers. On day 0, heifers [n=414; 317±23kg; 3.08±0.21 body condition score (1 to 5 scale) and 22-24 months of age] received a 1-g progesterone intravaginal device (Primer®, Agener União, Brazil) and 2mg of oestradiol benzoate, IM, (RIC-BE®, Agener União, Brazil). On day 8, the device was removed, were administered 500μg of sodium cloprostenol, IM, (Estron®, Agener União, Brazil) and heifers were divided in 2 groups: EC [n=213; 0.5mg EC, IM, (SincroCP®, Ouro Fino, Brazil) on day 8] and GnRH [n=201; 25μg of Licerelin, IM, (GestranPlus®, Agener União, Brazil) at TAI] TAI was performed 50h after device removal. Heifers were tail painted (Tell Tail®, GEA, New Zealand) to control oestrus expression from device removal to TAI. Heifers were scanned (7.5-MHz linear transducer MediSono® P3V, USA) to determine presence of CL (Day 0), ovulatory follicle diameter (OFD; Day 10) and ovulation (Day 11). Pregnancy was diagnosed 30 days after TAI. Oestrus expression was confirmed when marking ink was removed on day 10. Data were analysed using logistic regression and ANOVA. Oestrus expression was higher (P<0.05) in EC (93.90%, 200/213) compared to GnRH group (67.66%, 136/201). The OFD differed (P<0.05) according to presence of CL on Day 0 (10.3mm) or not (9.6mm), but was similar in treatment groups. Ovulation rate did not differ in EC (85%, 17/20) and GnRH (95%, 19/20) groups. Pregnancy rates were similar (P>0.05) between EC (52.58%, 112/213) and GnRH (59.20%, 119/201) groups; however, in heifers that expressed oestrus, rates were higher (P<0.05) (EC=56%, 112/200; GnRH=71.3%, 97/136) than in those did not show (EC=0%, 0/13; GnRH=33.8%, 22/65). Presence of CL at onset of TAI protocol was associated with higher pregnancy (P<0.05) in GnRH group (68%, 68/100) compared with EC (54.46%, 61/112) group, but in heifers without CL, pregnancy were similar for GnRH (50.5%, 51/101) and EC (50.5%, 51/101) groups. Heifers were also classified in 3 groups according OFD: small (≤9.5mm), medium (9.6-11.5mm), and large (≥11.6mm) to verify its effect on oestrus expression and pregnancy. Medium and large OFD were implicated in higher (P<0.05) oestrus expression [(EC=100%, 51/51; 96.97%, 32/33) and (GnRH=83.02%, 44/53; 97.44%, 38/39)] than small OFD [(EC=85%, 51/60) and (GnRH=23.8%, 15/63)]. Pregnancy was lower (P<0.05) in small OFD groups (EC=28.3%, 17/60; GnRH=25.4%, 16/63). In medium and large OFD, pregnancy was similar in EC (72.55%, 37/51; 54.55%, 18/33) groups, but differed (P<0.05) between GnRH large (82.05%, 32/39) and medium (62.26%, 33/53). Higher pregnancy was achieved in heifers with CL in the beginning of TAI protocol treated with GnRH. Size of ovulatory follicle was associated with higher oestrus behaviour and pregnancy rate in EC and GnRH treatments.