Search

Two experiments were designed to evaluate the impacts of supplementing lasalocid (LAS), narasin (NAR), or virginiamycin (VRM) on rumen fermentation parameters, apparent nutrient digestibility, and blood parameters (Exp. 1), as well as feed intake and performance (Exp. 2) of Nellore cattle consuming a forage-based diet. In Exp. 1, 32 rumen-fistulated Nellore steers (initial shrunk body weight [BW] = 355 ± 4.4 kg) were assigned to a randomized complete block design. Within block, animals were randomly assigned to one of four treatments: 1) forage-based diet without feed additives (CON), 2) CON diet plus 13 mg/kg of dry matter (DM) of NAR, 3) CON diet plus 20 mg/kg of DM of sodium LAS, or 4) CON diet plus 20 mg/kg of DM of VRM. No treatment effects were detected (P ≥ 0.32) for intake and apparent digestibility of nutrients. Steers fed NAR had the lowest (P ≤ 0.01) molar proportion of acetate on day 28, 56, and 112 vs. CON, LAS, and VRM steers, whereas acetate did not differ (P ≥ 0.25) between LAS, VRM, and CON steers from day 28 to 84. On day 112, steers fed LAS had a lower (P < 0.02) molar proportion of acetate vs. VRM and CON, whereas it did not differ between CON and VRM (P > 0.33). Steers receiving NAR had a greater (P ≤ 0.04) ruminal propionate vs. CON, LAS, and VRM, whereas LAS steers had greater (P < 0.04) propionate vs. CON and VRM steers on day 28 and 112, and it did not differ (P > 0.22) between CON and VRM. In Exp. 2, 160 Nellore bulls were blocked by initial shrunk BW (212 ± 3.1 kg) in a 140-d feedlot trial. Diets contained the same treatments used in Exp. 1. Bulls fed NAR had greater (P < 0.02) average daily gain (ADG) vs. CON and VRM, and similar (P = 0.17) ADG between NAR and LAS, whereas ADG did not differ (P > 0.28) between LAS, VRM, and CON bulls. A treatment effect was detected (P = 0.03) for dry matter intake, being greater in NAR vs. CON, LAS, and VRM bulls, and similar (P > 0.48) between CON, LAS, and VRM bulls. A tendency was detected (P = 0.09) for feed efficiency, which was greater (P < 0.02) in NAR bulls vs. CON and VRM, and similar (P = 0.36) between NAR and LAS bulls. From day 112 to 140, bulls receiving NAR were heavier (P < 0.03) vs. CON, LAS, and VRM bulls, but no differences were observed (P > 0.51) between CON, LAS, and VRM bulls. Collectively, ruminal fermentation profile and intake were impacted by NAR supplementation, which partially contributed to the enhanced performance of Nellore bulls receiving a forage-based diet.

This study aimed to evaluate the reproductive performance of ewes submitted to timed AI protocol with 7 (D7) or 9 (D9) days of progesterone. A total of 220 crossbred ewes (Doper × Santa Ines) were distributed in the treatments according to body weight (52.67 ± 11.76 kg), body condition score (2.5 ± 0.8; scale of 1-5), and the female category (multiparous, nulliparous and primiparous). Ewes received an intravaginal device of 0.3 g of progesterone (CIDR® Easy breed) on day 0, keeping in ewes for 7 or 9 days, which were the experimental treatments. At the time of P4 withdrawal, ewes received 300 IU of eCG (Novormon®) and 6.70 mg of dinoprost tromethamine (Lutalyse®). Insemination by laparoscopy was performed between 46 and 59 h after device removal, lasting from 1 to 5 min/ewe, which did not differ between protocols. The estrus detection rate was higher in the 9-day protocol compared to the 7-day protocol (82% and 65%, respectively, P = 0.0096). However, the 7-day protocol tended to increase pregnancy rate on the TAI compared to the 9-day protocol (45% and 33%, respectively, P = 0.09). The plasma concentration of progesterone at device removal was higher in the 7-day protocol than in the 9-day protocol (2.35 and 1.22 ng/mL, respectively, P = 0.04). We conclude that reducing the length of the estrus synchronization protocol to 7 days is recommended, which improved the reproductive response in ewes.

Made available in DSpace on 2021-06-25T10:10:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) This study investigated the effects of growth rates and compensatory growth on puberty attainment in Nellore heifers. Nellore heifers (n = 120), weaned at 8 ± 0.75 mo of age, were blocked by sire and BW (180 ± 8.6 kg) and assigned randomly to receive 1 of 4 treatments over a 10-mo period. Treatments included ad libitum feeding (high gain, HG), feed intake to gain 0.6 kg/d (medium gain, MG), restricted feeding (0.2 kg/d) for 4 mo followed by ad libitum feeding for 6 mo (compensatory gain, CG), and alternating periods of ad libitum and restricted feeding for 2 mo each throughout the trial (alternated CG, ACG). Puberty was assessed weekly by transrectal ultrasonography. Blood samples were collected at 8, 11, and 18 mo of age and at puberty to determine circulating concentrations of leptin. At 18 mo of age, nonpubertal heifers were treated with a puberty induction protocol using an intravaginal progestin device. There was no treatment effect (P = 0.17) on the percentage of heifers pubertal by 18 mo of age (HG: 66, MG: 40, CG: 58, and ACG: 52%), BW at puberty, and age at puberty. However, HG heifers had higher ADG (P < 0.01), dry matter intake (P < 0.01), and leptin concentrations (P = 0.03) than heifers from other groups. The response to the puberty induction protocol was similar (P = 0.90) among treatments. Regarding sire effects (genetic effects), there was an effect (P = 0.03) on the percentage of heifers pubertal by 18 mo of age and a tendency (P = 0.07) of sire effect in response to the puberty induction protocol. Compensatory growth appears to be an effective managerial approach to decrease feeding costs and stimulate puberty in Nellore heifers. Department of Nutrition and Animal Production College of Veterinary and Animal Science University of São Paulo, Duque de Caxias North Avenue, n 225 Department of Animal Science Federal University of Amazonas, Macurany Avenue, Jacareacanga Department of Animal Science Texas A&M University, 2471 TAMU Department of Animal Science College of Agriculture “Luiz de Queiroz” University of São Paulo, Pádua Dias Avenue, n 11, PO Box 09 College of Veterinary Medicine São Paulo State University (UNESP) College of Veterinary Medicine São Paulo State University (UNESP)

Two experiments were proposed to evaluate the addition of monensin for lambs fed diets containing a high level of mature ground flint corn. The experimental diets were as follows: no inclusion of monensin (M0) and inclusion of 8 (M8), 16 (M16) and 24 mg kg–1 of monensin (M24). In experiment 1, eight cannulated wethers were divided into a double 4 × 4 Latin square experimental design to evaluate nutrient digestibility, plasma parameters and rumen fermentation. The experiment lasted 112 days, divided into four periods of 28 days each. In experiment 2, ninety-two lambs were used in a randomized block design to evaluate the performance over 56 days. In experiment 1, doses of monensin had no effect on nutrient intake (p ≥ 0.07) and digestibility (p ≥ 0.09). There was a quadratic effect for acetate molar proportion (p = 0.01), acetate to propionate ratio (p = 0.04) and rumen pH (p < 0.01). However, there was no effect on the molar proportion of propionate and butyrate. The monensin decreased linearly the total SCFA concentration (p < 0.01). The inclusion of monensin increased glucose (p < 0.01) and decreased lactate concentration in plasma (p = 0.05). In experiment 2, monensin decreased dry matter intake (p = 0.04). However, there was a quadratic effect for average daily gain (p = 0.03) and feed efficiency (p < 0.01), with the greatest values observed for the M8 diet. Thus, the inclusion of 8 mg kg–1 of dry matter diet (DM) improves ruminal fermentation and plasma parameters, resulting in greater growth performance in lambs.

The study aimed to evaluate if the frequency of narasin supplementation impacts dry matter intake, ruminal fermentation parameters, and apparent digestibility of nutrient in Nellore (Bos indicus) steers fed forage-based diets. A total of 32 rumen-cannulated Nellore steers (initial body weight [BW] = 317 ± 27 kg; age =18 ± 1 mo) were assigned to individual pens in a randomized complete block design according to their initial shrunk BW. Within block, steers were randomly assigned to 1 of 4 treatments: 1) forage-based diet without the addition of narasin (CON; n = 8), 2) CON diet plus 13 ppm of narasin every 24 h (N24; n = 8), 3) CON diet plus 26 ppm of narasin every 48 hours (N48; n = 8), or 4) CON diet plus 39 ppm of narasin every 72 hours (N72; n = 8). The experimental period lasted 30 d, with 18 d for diet adaptation and 12 d for sample collection. The experimental diets contained 95% of Tifton-85 (Cynodon dactylon spp.) haylage and 5% ground corn used as a delivery vehicle for narasin. Ruminal fluid was obtained from d 25 to 30 at 6 h after feeding to determine ruminal fermentation parameters. Narasin supplementation frequency did not affect (P ≥ 0.22) nutrient intake and total tract apparent digestibility. Steers fed N24 and N48 had reduced (P = 0.02) ruminal acetate concentration compared with CON and N72. Daily supply of narasin increased (P = 0.01) the molar proportion of propionate compared with CON and N72, and it did not differ between N24 vs. N48, N48 vs. N72, and N72 vs. CON. Also, N48 steers had greater (P = 0.01) rumen propionate concentration compared with CON. The N24 treatment decreased the Ac:Prop (P = 0.01) and AcBut:Prop (P = 0.02) ratio compared with CON and N72, while N48 had reduced (P = 0.01) Ac:Prop and AcBut:Prop ratio when compared with CON steers. Steers fed N24 and N48 had greater (P = 0.04) ruminal short-chain fatty acids compared with CON, but it did not differ (P > 0.11) between N24, N48, and N72. Supplementing narasin to steers fed forage-based diets decreased (P < 0.01) ruminal ammonia concentration compared with CON steers regardless of supplementation frequency, being the least result observed for N24 steers. Collectively, narasin supplementation frequency affected fermentation parameters without altering the nutrient intake and total tract apparent digestibility. Hence, decreasing frequency of narasin supplementation to Nellore steers fed a forage-based diet did not reduce the capacity to modulate rumen fermentation parameters.

The aim of the present study was to evaluate the inclusion of narasin, salinomycin, or flavomycin for 140 d on ruminal fermentation parameters, apparent nutrient digestibility, and performance of Nellore cattle offered a forage-based diet. In experiment 1, 32 rumen-cannulated Bos indicus Nellore steers [initial body weight (BW) = 220 ± 12.6 kg] were assigned to individual pens in a randomized complete block design according to their initial shrunk BW. Within block, animals were randomly assigned to 1 of 4 treatments: (1) forage-based diet without feed additives (CON; n = 8), (2) CON diet plus 13 ppm of narasin (NAR; n = 8), (3) CON diet plus 20 ppm of salinomycin (SAL; n = 8), or (4) CON diet plus 3 ppm of flavomycin (FLA; n = 8). The experimental period lasted 140 d and was divided into 5 periods of 28 d each. The inclusion of feed additives did not impact (P ≥ 0.17) dry matter intake (DMI), nutrient intake, and apparent total tract digestibility of nutrients. Nonetheless, steers fed NAR had lower (P < 0.01) molar proportion of acetate compared with CON, SAL, and FLA steers, whereas ruminal acetate tended to be greater (P < 0.09) for SAL vs. CON and FLA, but did not differ (P = 0.68) between CON vs. FLA steers. Ruminal propionate was the highest (P < 0.01) for steers fed NAR and did not differ (P > 0.20) between CON, SAL, and FLA. Consequently, NAR steers had the lowest (P < 0.01) Ac:Pr ratio, whereas Ac:Pr did not differ (P > 0.18) among CON, SAL, and FLA. Total volatile fatty acids were greater (P < 0.04) for NAR and CON vs. SAL and FLA, but did not differ (P > 0.67) among NAR vs. CON and SAL vs. FLA. In experiment 2, 164 Nellore bulls (initial shrunk BW = 299 ± 2.5 kg) were assigned to feedlot pens for 140 d in a randomized complete block design. Within block (n = 10), animals were randomly assigned to the same treatments used in experiment 1. Average daily gain was greater (P < 0.01) in NAR vs. CON, SAL, and FLA bulls, and did not differ (P > 0.12) between CON, SAL, and FLA bulls. Bulls fed NAR had greater (P < 0.02) DMI (as kg/d or % BW) and final shrunk BW compared with CON, SAL, and FLA bulls, whereas DMI and final shrunk BW did not differ (P > 0.26) between CON, SAL, and FLA bulls. Feed efficiency, however, was not impacted (P = 0.51) by any feed additives used herein. Collectively, narasin was the only feed additive that benefited performance and ruminal fermentation of Nellore animals fed a forage-based diet.

This study aimed to evaluate the effect of polyunsaturated fatty acids (FA) sources (soybean oil, linseed oil and fish oil) on apparent nutrient digestibility, milk composition, and the FA profile in the arterial blood plasma and the milk from dairy goats. Four multiparous Saanen goats were assigned to receive the experimental diets: control diet (no additional oil, with 425 g/kg DM of corn), or a diet substituting 20 g/kg DM of corn by either soybean oil (SO), linseed oil (LO) or fish oil (FO), which were arranged in a 4 × 4 Latin square design. The goats were housed in individual tie stalls, where they received diets containing 400 g/kg DM of corn silage and 600 g/kg DM of concentrate. The corn substitution by FAs sources did not affect apparent nutrient digestibility and milk composition (macro compounds). The oil sources changed the plasma and milk fatty acids profile differently. The plasma concentration of vaccenic and rumenic acids were strongly increased (P

The changes promoted by feed additives in ruminal fermentation, especially increasing the availability of propionate, can improve the energy balance of an animal, which is of great importance in the lactation period. This trial aimed to evaluate the inclusion of narasin in the diet of lactating ewes on milk yield, composition, dry matter intake (DMI), and plasma metabolites of the ewes and growth rate of lambs. Thirty-two lactating ewes (59.0 ± 2.42 kg) were assigned to a randomized complete block design. The experimental diets contained 500 g/kg of dry matter (DM) of coast cross (Cynodon dactylon (L.) Pers) hay and 500 g/kg DM of concentrate, and the treatments were: N0—no narasin inclusion; N13—inclusion of 13 mg of narasin/kg DM. Once a week, from week 2 to 10 of lactation, ewes were separated from their lambs, injected with oxytocin, and milked mechanically to empty the udder. After 3 h, the milk production was recorded, using the same procedure, and sampled to evaluate the composition. The blood samples were taken weekly, 4 h after feeding. The average daily gain (ADG) and starter DMI of the lambs were evaluated weekly from week 2 to 12 of age. The inclusion of narasin did not affect (P = 0.93) DMI of ewes; however, it increased milk production (P < 0.01) and feed efficiency (P = 0.02; FE). Ewes fed N13 had a greater milk fat (P < 0.01), protein (P < 0.01), lactose (P = 0.04), and total solids production (P < 0.01). Narasin inclusion in ewe’s diet increased plasma glucose concentration (P = 0.05) at weeks 8, 9 and 10; however, there was no effect on plasma urea concentration (P = 0.96). The lambs of N0 ewes had a greater starter DMI (P < 0.01) at weeks 7, 8, 9, and 10; however, the ADG and body weight at weaning and after weaning were similar between treatments (P > 0.05). The results showed that the inclusion of 13 mg of narasin/kg DM improved the milk production and FE of the ewes without altering the composition of the milk. The lower initial consumption of concentrate by N13 lambs before weaning was caused by the higher production of milk. The results obtained in the present study demonstrate the possible productive gain with the inclusion of narasin in diets for lactating ewes.

Narasin is a feed additive used to alter ruminal fermentation and increase performance of cattle fed forage-based diets. The present study had two objectives: 1) to define the best dose of narasin for lambs fed forage-based diets; 2) evaluate whether the quality of the forage used can affect the action of narasin on performance of lambs. In Exp. 1, fifty-one crossbred ewe’s lambs [Dorper × Santa Ines; initial body weight (BW) = 25.9 ± 0.07 kg and 145 ± 2.1 d of age], were stratified by initial BW and randomly allotted in a tie-stall system in a randomized complete block design with 17 blocks and 3 treatments. The treatments for the 63-d feeding trial consisted of: 1) forage-based diet without narasin (CONT; n = 17), 2) CONT diet plus 13 ppm of narasin (13 N; n = 17), and 3) CONT diet plus 20 ppm of narasin (20 N; n = 17). Experimental diets were composed by 80 % of coastcross hay (Cynodon dactylon spp.) and 20 % of concentrate, which was used as delivery vehicle for the narasin treatments. Narasin inclusion increased (P 0.49) among hay quality and narasin inclusion for any variable analyzed. Hay with high CP increased (P

The objective of this work was to evaluate the effect of narasin inclusion in mineral and protein supplements on the performance and supplement intake of grazing beef yearlings. One hundred and fifty Nellore yearlings with 17.0±0.06 months of age and 219.7±1.62 kg initial body weight (BW) were allocated into 30 experimental units (EUs), with five animals each. The EUs were assigned to 16 paddocks, which were continuously stocked for 28 days, followed by 28 days of rest. A randomized complete block design was used. The experiment lasted 140 days, divided into five periods of 28 days each. The assessed treatments were: control mineral supplement (CON); CON + 1,800 (N1800) or 2,750 (N2750) mg narasin per kilogram of supplement; and protein mineral supplement (PROT) or PROT + 360 mg narasin per kilogram of supplement (PROT 360). The inclusion of narasin in the mineral supplement increased average daily gain (ADG) in the first period and decreased supplement intake in the first, second, and third periods, when compared with the CON treatment. The ADG and supplement intake were similar between the N1800 and N2750 treatments. Narasin has a positive effect on ADG up to 28 days of supplementation and controls mineral supplement intake, without compromising this gain. Resumo: O objetivo deste trabalho foi avaliar a inclusão de narasina em suplementos mineral e proteico sobre o desempenho e o consumo de suplemento de novilhos de corte em pastagem. Cento e cinquenta novilhos Nelore com 17,0±0,06 meses de idade e 219,7±1,62 kg de peso inicial foram distribuídos em 30 unidades experimentais (UEs), com cinco animais cada uma. As UEs foram dispostas em 60 piquetes, os quais foram pastejados continuamente por 28 dias, seguidos de 28 dias de descanso. Utilizou-se o delineamento de blocos ao acaso. O tempo de duração do experimento foi de 140 dias, dividido em cinco períodos experimentais de 28 dias cada um. Os tratamentos avaliados foram: suplemento mineral controle (CON); CON + 1.800 (N1800) ou 2.750 (N2750) mg de narasina por quilograma de suplemento; e suplemento mineral proteinado (PROT) ou PROT + 360 mg de narasina por quilograma de suplemento (PROT 360). A inclusão de narasina na mistura mineral aumentou o ganho médio diário (GMD) durante o primeiro período e reduziu o consumo de suplemento no primeiro, no segundo e no terceiro períodos, quando comparado ao tratamento CON. O GMD e o consumo de suplemento foram semelhantes entre os tratamentos N1800 e N2750. A narasina tem efeito positivo no GMD até 28 de suplementação e controla o consumo de suplemento mineral, sem comprometer esse ganho.

Made available in DSpace on 2021-06-25T11:20:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 The objectives were to evaluate the effects of two non-fibrous carbohydrate sources and the rate of body weight gain on puberty status in ewe lambs. Sixty ewe lambs (1/2 Dorper x 1/2 Santa Ines) with an initial body weight of 25.1 +/- 4.1 kg and 102.8 +/- 1.5 days old were distributed in a randomized complete block design with 10 blocks and 3 treatments. The trial lasted 119 days, in which performance was evaluated on days 28, 56, 84, and 119, and puberty status was every week evaluated by progesterone concentration. The treatments were characterized by the inclusion of different carbohydrate sources in the diets in order for ewe lambs to reach different rates of body weight gain: CORN, total diet containing 46% of corn (% DM); PCP, total diet containing 46% of pelleted citrus pulp (% DM); and HAY, total diet containing 80% of coastcross hay (% DM). The CORN- and PCP-based diets were formulated for an average daily gain (ADG) of 0.200 kg/day and a HAY-based diet for an ADG of 0.100 kg/day. There was an interaction between treatments and experimental periods for dry matter intake (DMI) (P < 0.01), in which lambs in the CORN treatment presented DMI similar to PCP in the first and second periods, but lambs from the PCP treatment presented lower DMI than the CORN treatment in subsequent periods. In all periods, the body weight, average daily gain, and feed efficiency of CORN lambs were similar to PCP lambs, but higher thanHAY lambs. The age at puberty was not affected by treatments; however, lambs fed with non-fibrous carbohydrate sources reached puberty heavier (P < 0.0001) than lambs from the HAY treatment. Despite the high increase in body weight for lambs fed with non-fibrous carbohydrate sources, it did not affect the age of puberty. Univ Sao Paulo, Dept Anim Sci, Coll Agr Luiz de Queiroz, Padua Dias Ave 11,POB 09, BR-13418900 Piracicaba, SP, Brazil Univ Fed Amazonas, Dept Anim Sci, Gen Rodrigo Octavio Ave 6200, BR-69152240 Manaus, Amazonas, Brazil Univ Estadual Ponta Grossa, Dept Anim Sci, Gen Carlos Cavalcanti Ave 4748, BR-84030900 Ponta Grossa, Parana, Brazil Univ Sao Paulo, Coll Vet & Anim Sci, Dept Nutr & Anim Prod, Duque Caxias North Ave 225, BR-13635000 Pirassununga, SP, Brazil Sao Paulo State Univ, Sch Engn, Brasil Ave 56, BR-SAO PAUL Ilha Solteira, SP, Brazil Sao Paulo State Univ, Sch Engn, Brasil Ave 56, BR-SAO PAUL Ilha Solteira, SP, Brazil

This trial aimed to evaluate the effects of thyme essential oils (EO) on rumen parameters, nutrient digestibility and nitrogen balance in wethers fed with high-concentrate diet. Twenty rumen-cannulated wethers were blocked according to body weight (BW= 64.0±2.1kg), and received one of the following treatments: 25mg of monensin/kg of dry matter (DM; MON) or doses of thyme EO (1.25, 2.50 or 3.75g/kg of DM). The diet was composed of 90% concentrate. Thyme EO was composed mainly by thymol (46.6% of DM) and p-cymene (38.9% of DM). The nutrient intake and apparent digestibility were similar among treatments. The inclusion of 3.75g of thyme EO tended (P= 0.07) to increase butyrate compared to MON and 1.25OE and wethers fed with 1.25g of thyme EO tended (P= 0.07) to decrease ruminal pH on the 14th day compared to MON. The treatments did not affect acetate:propionate ratio, total short chain fatty acids (SCFA) and nitrogen retention. Results from this study suggest that adding thyme EO to high-concentrate diets may be used as an alternative to monensin as feed additive in feedlot lambs.

The aim of this study was to evaluate three feed additives for rumen manipulation. Thirty-two rumen-fistulated animals were assigned to a completed randomized block design, according to their initial BW. Steers were fed with 99% of coastcross haylage and 1% of concentrate, used as vehicle for the additives. The forage and concentrate were offered separately, whereas the forage was offered after the entire consumption of the concentrate. The experimental diets consisted in: CON = Control (no feed additive); NAR = 13ppm of Narasin; SAL = 20ppm of Salinomycin; and FLA = 3ppm of Flavomycin. The experimental period lasted 140 d, divided on 5 periods of 28 d each. Rumen fluid was collected on d 0, 28, 56, 84, 112 and 140, at 0, 6 and 12 hours after feeding and combined as a pool for SCFA analysis. Data were analyzed using the MIXED procedure of SAS. Data obtained on d 0 were used as covariate. Tukey test 5% was used for comparisons. There was treatment effect on acetate (CON: 73.5ab; NAR: 73.0a; SAL: 73.9b and FLA: 73.6b mM/100mM, P = 0.01; SEM = 0.16), propionate (CON: 13.7b; NAR: 14.6a; SAL: 13.5b and FLA: 13.4b, P = 0.01; SEM = 0.11), butyrate (CON: 9.06a; NAR: 8.64b; SAL: 8.72ab and FLA: 8.96ab, P = 0.02; SEM = 0.10), isovalerate (CON: 1.51b; NAR: 1.61ab; SAL: 1.55ab and FLA: 1.67b, P = 0.03; SEM = 0.04) and ac:prop ratio (CON: 5.39a; NAR: 4.99b; SAL: 5.49a and FLA: 5.4a, P = 0.01; SEM = 0.05). Therefore, narasin improves energetic efficiency of ruminal fermentation compared to other additives.

The aim of this study was to compare the effects of three additives (narasin, lasalocid, and virginiamycin) on the performance of bulls fed a high-forage diet. One hundred and sixty Nellore (Bos indicus) yearling bulls were assigned to a randomized completed block design, according to initial BW (212.5 kg ± 3.1; 10 pen/treatment; 4 animals/pen). Yearling bulls were fed daily and diets were composed of 96% of coastcross haylage (12% CP) and 4% of concentrate, used as the delivery vehicle for the additives. Once a day, the concentrate and forage were offered separately. The forage was offered after the entire consumption of the concentrate. The experimental diets consisted of CON: Control (no additives); NAR: 13 ppm of narasin; LAS: 20 ppm of lasalocid; and VIR: 20 ppm of virginiamycin. The experimental period lasted 140 d and the yearling bulls were individually weighed at d 0, 28, 56, 84, 112 e 140 after 14h of feed and water restriction. The orts were recorded to determine the DMI. Data were analyzed as repeated measures over time using the MIXED procedure of SAS and the LSMEANS option was used to generate individual means. There was a treatment effect on DMI (CON: 5.26b: NAR: 5.69a; LAS: 5.16b; VIR: 5.11b kg/d; SEM = 0.14; P = 0.03), ADG (CON: 0.451b; NAR: 0.557a: LAS: 0.498ab; VIR:0.459b kg; SEM = 0.03; P = 0.04), FE (0.080c, 0.095a, 0.092ab and 0.085bc; SEM = 0.0044; P = 0.05) and final BW (CON: 273.9b; NAR: 287.8a; LAS: 277.1b; VIR: 275.7b kg SEM = 3.4; P = 0.03). In conclusion, the inclusion of 13 ppm of narasin improves the performance of yearling bulls fed high-forage diets.

The objective of this study was to determinate the effects of narasin on carcass characteristics of lambs fed a diet containing different levels. Forty-four lambs were allotted in a randomized complete block design, defined by initial body weight (BW), in a 2x2 factorial arrangement. The first factor was forage (coastcross hay) inclusion (10 or 20%, DM basis) and the second factor was narasin (0 or 13 ppm). The experimental diets were isonitrogenous (17.4%, DM basis). The experiment lasted 112 days. At the end of the experiment, the lambs were slaughtered to evaluate the carcass characteristics and meat composition. Data were analyzed using the MIXED procedure of SAS and the LSMEANS option was used to obtain the means. The effects were considered significant when P < 0.05. There was no interaction between forage levels and narasin inclusion. The experimental diets did not affect the slaughter BW (54.8 ± 1.6 kg), hot carcass weight (29.3 ± 0.96 kg), dressing percentage (53.5 ± 0.67%) and LM area (18.8 ± 0.89 cm2). The inclusion of narasin increased 12th-rib fat (2.10 vs 2.75 mm; P < 0.01) and BW thickness (16.9 vs 20.2 mm; P < 0.01). The inclusion of 20% of hay decreased BW thickness (19.21 vs 17.9 mm; P = 0.03). The experimental diets did not affect the moisture (74.2 ± 0.53%) and ash content in meat (1.27 ± 0.04%). Narasin inclusion increased the fat (2.81 vs 3.62%; P < 0.01) and decreased the CP (21.3 vs 20.7%; P = 0.02) in meat composition. The inclusion of 10% of hay increased the fat in meat (3.5 vs 2.9%; P = 0.03), however, did not affect the CP content. In conclusion, the narasin inclusion and levels of hay improve the carcass characteristics and change the meat composition.

This study evaluated the frequency of narasin supplementation on ruminal fermentation in lambs. Four male lambs (castrated and cannulated in the rumen) were used in a 4 x 4 Latin square experimental design. The experimental diets consisted of 95% coastcross hay (16% CP) and 5% ground corn (DM basis), used as the delivery vehicle for the narasin. The diet was fed daily. The treatments were: C (no additives), N24: narasin offered every 24 hours at 13 ppm; N48: narasin offered every 48 hours, being 26 ppm offered on the first day and ground corn without narasin on the second day; N72: narasin offered every 72 hours, being 39 ppm offered on the first day and ground corn without narasin on the second and third days. The trial lasted 4 periods of 36 days each. Between the 31st to 36th days of each period, the rumen fluid was collected (hours 0; 6 and 12). All data were analyzed using the MIXED procedure of SAS and the treatments were compared through the Tukey test at 5% probability. There was no effect at the molar concentration of acetate (76.25 ± 1.22 mM/100mM), butyrate (4.9 ± 0.59 mM/100mM), ammonia (15.17 ± 2.03 mg/dl) and pH (6.36 ± 0.13). There was an effect of the molar concentration of propionate (C = 15.88b; N24 = 17.35a; N48 = 16.91a; N72 = 16.57ab mM/100mM; P < 0.01), acetate:propionate ratio (C = 4.86; a N24 = 4.38 b; N48 = 4.53b; N72 = 4.66ab; P < 0.01) and the total SCFA (C = 88.96b; N24 = 107.43 a; N48 = 100.53a; N72 = 84.62b mM; P < 0.01). In conclusion, the daily supply of narasin and every 48 hours positively affected ruminal fermentation parameters in lambs, but this effect decreased when used every 72 hours.

The objective of this study was to determine the effects of forage levels and narasin inclusion in diets on the rumen parameters in feedlot lambs. Forty-four lambs were allotted in a randomized complete block design, defined by initial body weight, in a 2x2 factorial arrangement. The first factor was forage inclusion (10 or 20% of coastcross hay, DM basis) and the second factor was narasin (0 or 13 ppm). The experimental diets were isonitrogenous (17.4%, DM basis). At the end of the experimental period, the lambs were slaughtered without fasting, and the rumen fluid was collected to determinate pH and short chain fatty acid (SCFA). Data were analyzed using the MIXED procedure of SAS and the LSMEANS option was used to obtain the means. The effects were considered significant when P < 0.05. There was an interaction between hay and narasin on the molar proportion of propionate (P = 0.02) and the acetate:propionate ratio (P < 0.01). Narasin inclusion in diets containing 20% forage increased propionate (25.4 vs 37.1 mM/100mM; P = 0.02); however, there was no effect in diets containing 10% forage (35.9 ± 1.75 mM/100Mm). Consequently, the narasin decreased acetate:propionate ratio in diets containing 20% forage (2.57 vs 1.42; P < 0.01), and no effect was observed 10% forage diets (1.40 ± 0.14). The inclusion of narasin increased the total SCFA (86.2 vs 115.4 mM; P < 0.01), ruminal pH (6.26 vs 6.49; P = 0.05) and decreased acetate (55.6 vs 47.6 mM/100mM; P < 0.01). The inclusion of 20% forage increased acetate when compared with 10% hay (54.99 vs 48.19 mM/100mM; P < 0.01) and the pH ruminal (6.25 vs 6.49; P = 0.04). The experimental diets did not affect the butyrate. In summary, the narasin inclusion and forage levels content change rumen parameters in feedlot lambs.

The objective of this study was to determinate the effects of forage levels and narasin inclusion on the performance of feedlot lambs. Forty-four lambs were allotted in a randomized complete block design, defined by initial body weight (BW), in a 2x2 factorial arrangement. The first factor was forage (coastcross hay) inclusion (10 or 20%, DM basis) and the second factor was narasin (0 or 13 ppm). The experimental diets were isonitrogenous (17.4%, DM basis). The experiment lasted 112 days, divided into two periods of 56 d each. The lambs were weighed after a fasting period of 14 hours on days 0, 56, and 112. Average daily gain (ADG), dry matter intake (DMI) and feed efficiency (FE) were determined in each period. Data were analyzed as repeated measures over time using the MIXED procedure of SAS and the LSMEANS option was used to obtain the means. The effects were considered significant when P < 0.05. There was no interaction between forage levels and narasin inclusion. Narasin did not affect the DMI, ADG, and FE. There was hay levels and period interaction for DMI and ADG. Increase levels of hay did not affect the DMI during the first period; however, 20% of hay inclusion increased DMI in the second period (1.16 vs 1.30 kg/d; P = 0.01). The inclusion of 10% of hay increased the ADG in the first period (0.28 vs 0.24 kg/d; P < 0.01), however, there was no effect in the second period. Consequently, 10% of forage inclusion increased the FE (0.23 vs 0.21; P = 0.01). In summary, diets containing 10% of forage improves the FE, and narasin inclusion did not affect the lamb’s performance.

Essential oil (EO) from Brazilian red pepper fruit contains compounds with antimicrobial activity, and could be possible substitutes for the antibiotics commonly used in ruminant nutrition. Te objectives of the present study were to evaluate the efects of the Brazilian red pepper fruit EO (Schinus terebinthifolius) as a substitute for monensin on performance, carcass characteristics and meat of lambs fed high concentrate diets. Forty-eight lambs were used, 24 males (20 ½ Dorper × ½ Santa Inês and 4 Santa Inês) and 24 females (24 ½ Dorper × ½ Santa Inês), with 21.54 ± 0.88 kg of initial body weight (BW) and 78 ± 2.4 days of age, in a randomized complete block design. Te experiment lasted 56 days, divided into 2 periods of 28 days each. Te treatments were defned by the inclusion in diets of 8 ppm of monensin (MON), and the doses 0.14% (14EO), 0.28% (28EO) and 0.42% (42EO) of red pepper fruit EO. Te additives were included in a base diet with a 10:90 of forage to concentrate ratio. At the end of 56 days, 32 animals were slaughtered for the measurement of carcass parameters and meat composition. Tere was no interaction among treatments and periods for average daily gain (P = 0.08), DM intake (P = 0.36), feed efciency (P = 0.24) and oocyst of Eimeria ssp. in feces (P = 0.46). Te treatments did not afect (P > 0.05) the average daily gain (ADG), dry matter intake (DMI) and feed efciency. Lambs fed diets containing monensin had less (P < 0.01) oocyst/g compared with the diet 14EO. Tere was no efect of diets on carcass characteristics. Te treatments with higher doses of the Brazilian red pepper fruit EO had reduced mineral content of meat compared to monensin. Te red pepper fruit EO demonstrated the potential to replace monensin in feedlot lambs fed high concentrate diets, maintaining performance and carcass characteristics. However, the monensin has greater capacity to control coccidiosis in feedlot lambs. Os óleos essenciais (OE) dos frutos de aroeira possuem compostos com atividade antimicrobiana, sendo possíveis substitutos aos antibióticos comumente utilizados na nutrição de ruminantes. Os objetivos do presente estudo foram avaliar os efeitos da inclusão do óleo essencial de aroeira fruta (Schinus terebinthifolius) como substituto da monensina sobre o desempenho, características de carcaça e da carne de cordeiros alimentados com dietas contendo elevado teor de concentrado. Foram utilizados 48 cordeiros, 24 machos (20 ½ Dorper × ½ Santa Inês e 4 Santa Inês) e 24 fêmeas (24 ½ Dorper × ½ Santa Inês), com peso inicial de 21,54 ± 0,88 kg e 78 ± 2,4 dias de idade, em delineamento de blocos completos casualizados. O experimento teve duração de 56 dias, divididos em 2 períodos de 28 dias cada. Os tratamentos foram defnidos pela inclusão na dieta de 8 ppm de monensina sódica (MON) e as doses de 0,14% (14EO), 0,28% (28EO) e 0,42% (42EO) de óleo essencial dos frutos da aroeira. As dietas experimentais foram compostas por 10% de volumoso e 90% de concentrado. Ao fnal dos 56 dias, 32 animais foram abatidos para a mensuração dos parâmetros de carcaça e análise química da carne. Não houve interação entre tratamento e período para o ganho médio diário (P = 0,08), consumo de MS (P = 0,36), efciência alimentar (P = 0,24) e contagem de oocistos de Eimeria ssp. (P = 0,46). Não houve efeito (P > 0,05) dos tratamentos no ganho de peso médio diário (GMD), consumo de matéria seca (CMS) e efciência alimentar (EA). Cordeiros alimentados com dietas contendo monensina tiveram menor (P < 0,01) contagem de oocistos/g de fezes comparado com a dieta 14OE. Não houve efeito das dietas sobre as características de carcaça.A inclusão de 0,28 e 0,42% de OE de aroeira fruto reduziram a concentração de matéria mineral da carne dos cordeiros comparados ao tratamento MON. O OE dos frutos da aroeira demonstrou capacidade de substituir a monensina, apresentando resultados similares com relação ao desempenho e características de carcaça. Entretanto, a monensina apresentou maior capacidade no controle de coccidiose.

A puberdade de novilhas de corte é um fator limitante para o aumento da produtividade, sendo influenciada por diversos fatores. O objetivo desse estudo foi avaliar o ritmo de ganho de peso dos três aos sete meses de idade e a DEP do touro na puberdade de novilhas de corte. Foram utilizadas 60 novilhas F1 (Angus x Nelore) desmamadas precocemente (102 ± 4,3 dias; 103 ± 4,7 kg) em um experimento arranjado em esquema fatorial 2x2. O fator 1 foi o Ritmo de Ganho no período 1 (3 a 7 meses de idade) no qual as novilhas foram submetidas a Alto GMD, com CMS ad libitum (GA; GMD estimado em 1000 g/animal/dia, n = 30 novilhas) ou submetidas a Médio GMD, com CMS de 1,5% do peso corporal (GM; GMD estimado em 700 g/animal/dia, n = 30 novilhas). No período 2 (do 7o mês de idade até a puberdade), todas as novilhas receberam a dieta ad libitum. O fator 2 foi a DEP para circunferência escrotal (CE) do touro progenitor da novilha, sendo considerados sexualmente precoces os touros com DEP Positiva (DP) e tardios os touros com DEP Negativa (DN). Foram mensurados os GMD, CMS, EA ao final de cada período; peso aos sete meses; idade, peso e ECC na puberdade; taxa de puberdade e concentrações séricas de IGF-1 e insulina nos meses 3, 5, 7, 10 e 12. A análise estatística foi realizada pelo SAS 9.3. Houve interação entre os fatores apenas para CMS no período 1 (P = 0,02). Considerando o Ritmo de Ganho, novilhas do GA apresentaram maiores CMS (P < 0,0001) e GMD (P < 0,0001) no período 1 em relação a novilhas do GM. Em consequência, o peso aos sete meses também foi maior (P = 0,002). No período 2, as novilhas GM apresentaram GMD superior (P = 0,05) as novilhas GA. Considerando a DEP, novilhas de DP apresentaram maiores CMS (P = 0,03) e GMD (P = 0,07) no período 2, em relação a novilhas de DN. As novilhas DP foram mais pesadas aos sete meses (P = 0,02) e na puberdade (P = 0,0005). A taxa de puberdade aos 15 meses foi maior para as novilhas DP (P = 0,03). Não houve redução da idade à puberdade de novilhas Angus x Nelore pela diferença no Ritmo de Ganho dos 3 aos 7 meses. A DEP para CE de touros precoces aumentou a taxa de puberdade de novilhas Angus x Nelore aos 15 meses de idade. The puberty in beef heifers is a limiting factor for the increase of productivity, being influenced by several factors. The aim of this study was to evaluate the rate of weight gain from three to seven months of age and the EPD of the bull on puberty of beef heifers. Sixty F1 heifers (Angus x Nellore) weaned early (102 ± 4.3 days; 103 ± 4.7 kg) were used in an experiment arranged in a 2x2 factorial scheme. Factor 1 was the Rate of Gain in period 1 (3 to 7 months of age) in which heifers were submitted to High ADG, with DMI ad libitum (HG; ADG estimated at 1000 g / animal / day, n = 30 heifers ) or submitted to Medium ADG, with DMI of 1.5% of body weight (MG; GMD estimated at 700 g / animal / day, n = 30 heifers). In period 2 (from the 7th month of age until puberty), all heifers received the ad libitum diet. Factor 2 was the EPD for scrotal circumference (SC) of the sire: Positive EPD (PE) of the precocious sires and Negative EPD (NE) of the non-precocious sires. ADG, DMI and FE were measured at the end of each period; weight at seven months; age, weight and BCS at puberty; rate of puberty and serum concentrations of IGF-1 and insulin at months 3, 5, 7, 10 and 12. Statistical analysis were performed by SAS 9.3. There was interaction between factors only for CMS in period 1 (P = 0.02). Considering the Rate of Gain, HG heifers showed higher DMI (P

This study aimed to evaluate the effect of progesterone (P4) device reutilization in long and short protocols for transcervical timed artificial insemination (TAI) in Santa Ines ewes. A total of 275 multiparous lactating ewes were blocked according to body weight (BW, 49.1 ± 7.3 means ± SE), body condition score (BCS, 2.9 ± 0.4; scale of 1–5), and days postpartum (50 ± 8.2 days), and allocated to one of the treatments. The treatments were arranged in a factorial design, in which the factor 1 was the P4 device type (new or a device of 0.3 g of P4 previously used by 11 days), and the factor 2 was the short or long TAI protocol (P4 device remained by 7 or 11 days, respectively). At device removal, all ewes received 300 IU eCG and 6.70 mg of Dinoprost tromethamine. After TAI protocol, ewes remained with ram by 21 days. There was no interaction between factors in any variables. Ewes that received a new P4 device delayed (P = 0.05) to show estrus compared with ewes receiving a previously used P4 device, but it did not affect pregnancy rate. The long protocol tended to increase pregnancy rate compared with short protocol (33% vs. 24%, respectively; P = 0.07). However, the pregnancy rate at the end of reproductive period was similar in both groups (about 84%). Thus, the use of long protocols tended to improve reproductive performance, and the reused P4 device did not affect pregnancy rate.

Two experiments were conducted to evaluate the effect of thyme (Thymus vulgaris) essential oil (EO) doses on rumen fermentation, nutrient digestibility, and nitrogen metabolism, as well as performance and coccidia oocyst discharge. In experiment I, 20 rumen-cannulated wethers received the experimental diets containing 80% dry matter (DM) of haylage and 20% DM of concentrate. Treatments were 25mg of monensin/kg DM or doses of 1.25, 2.50, or 3.75g of thyme EO/kg DM. In experiment II, 50 ewe lambs received the same diets from experiment I, including a diet without feed additives. Wethers fed with diets containing 1.25g/kg DM of thyme EO had higher molar proportion of propionate (P= 0.03) and butyrate (P< 0.01), and lower (P= 0.04) acetate to propionate ratio than other treatments. Adding thyme EO to diets increased (P= 0.02) nitrogen retention compared to monensin. The performance of ewe lambs was not affected (P≥ 0.05) by treatments. However, lambs fed monensin had a lower (P= 0.04) number of coccidia oocyst discharge than others. Adding 1.25g/kg DM of thyme EO in high-forage diet improved ruminal fermentation. Thyme EO enhanced nitrogen metabolism, however, it did not improve performance.

This study aimed to evaluate the effect of progesterone (P4) device reutilization in long and short protocols for transcervical timed artificial insemination (TAI) in Santa Inês ewes. A total of 275 multiparous lactating ewes were blocked according to body weight (BW, 49.1 ± 7.3 means ± SE), body condition score (BCS, 2.9 ± 0.4; scale of 1-5), and days postpartum (50 ± 8.2 days), and allocated to one of the treatments. The treatments were arranged in a factorial design, in which the factor 1 was the P4 device type (new or a device of 0.3 g of P4 previously used by 11 days), and the factor 2 was the short or long TAI protocol (P4 device remained by 7 or 11 days, respectively). At device removal, all ewes received 300 IU eCG and 6.70 mg of Dinoprost tromethamine. After TAI protocol, ewes remained with ram by 21 days. There was no interaction between factors in any variables. Ewes that received a new P4 device delayed (P = 0.05) to show estrus compared with ewes receiving a previously used P4 device, but it did not affect pregnancy rate. The long protocol tended to increase pregnancy rate compared with short protocol (33% vs. 24%, respectively; P = 0.07). However, the pregnancy rate at the end of reproductive period was similar in both groups (about 84%). Thus, the use of long protocols tended to improve reproductive performance, and the reused P4 device did not affect pregnancy rate.

Narasin is an antibiotic ionophore that may change rumen fermentation; however, the effects on the post-rumen are unknown. The objective of this study was to determinate the effects of different levels of hay and narasin inclusion on the cecal parameters of lambs. Forty-four lambs were allotted in a randomized complete block design, defined by initial BW, in a 2x2 factorial treatment arrangement. The first factor was forage (coastcross hay) inclusion (10 or 20%, DM basis) and the second factor was narasin (0 or 13 ppm). The experimental diets were isonitrogenous (17.4%, DM basis) and the experiment lasted 112 days. At the end of the experimental period, the lambs were slaughtered without fasting, and the cecal fluid was collected to determinate pH and short chain fatty acid (SCFA). Data were analyzed using the MIXED procedure of SAS. The effects were considered significant when P < 0.05. There was no interaction between forage content and narasin inclusion. Narasin increased the molar concentration of propionate (N0: 19.4; N13: 21.4 mM/100mM; P = 0.02) and decreased isobutyrate (N0: 1.6; N13: 0.7 mM/100mM; P = 0.05) and acetate:propionate ratio (N0: 3.4; N13: 2.9; P = 0.03). The valerate was greater in diets with 10% hay when compared of diets 20% (H10: 2.0; H20: 1.3 mM/100mM; P < 0.01). The experimental diets not affect the molar proportion of acetate (62.7±1.3 mM/100mM), butyrate (12.9 ± 0.7 mM/100mM), isovalerate (1.3 ± 0.5 mM/100mM) total SCFA concentration (68.6 ± 8.5 mM) and cecal pH (6.2 ± 0.14). Therefore, the inclusion of 13 ppm of narasin changes the cecal fermentation in high concentrate diets. In addition, the inclusion of 10 or 20% of hay has a little influence on cecal fermentation.

High-grain diets have been used with great success in the feedlot systems for lambs production in Brazil. Then it became important to define the ideal dietary fiber content in the diet when the goal is to produce heavy lambs for early slaughter. The objective in this trial was to evaluate the levels of fiber on performance of lambs feed high-grain diet. Fifty-eight Dorper x Santa Inês ram lambs (initial BW 20.7 ± 1.19 kg and 75 ± 10.83 d old) were assigned to a randomized complete block design. The treatments were defined by the fiber (“Coastcross” hay) content in diets (CP: 16,12% ± 0.92): 0F: no forage diet (NDF: 10.4%); 5F: 5% of forage (NDF: 12.1%); 10F: 10% of forage (NDF: 15%); 15F: 15% of forage (NDF: 15.5%); 20F: 20% of forage (NDF: 20.8%) and 25F: 25% of forage (NDF: 23.5%). The experiment lasted 89 days and lambs were weighted after 16 hours fasting on days 0, 31, 57 and 89. DMI, ADG and FE were determined in each period. There was no interaction effect between diets and periods. There was a quadratic effect in DMI (0F: 0.96; 5F: 0.97; 10F: 1.04; 15F: 1.00; 20F: 1.02; 25F: 0.88 kg/d; P = 0.02), ADG (0F: 0.27; 5F: 0.26; 10F: 0.28; 15F: 0.28; 20F: 0.26; 25F: 0.21 kg/d; P = 0.01) and FE (0F: 0.28; 5F: 0.28; 10F: 0.28; 15F: 0.29; 20F: 0.26; 25F: 0.25; P = 0.05). Consequently, the increased levels of forage result in quadratic effect on final BW (0F: 44.5; 5F: 44.7; 10F: 46.1; 15F: 45.5; 20F: 43.9; 25F: 39.7 kg; P < 0.01). In conclusion, the inclusion of 10–15% of forage improves the performance of feedlot lambs feed high-concentrate diets, but it was proved the real possibility of finishing lambs with diet without forage source.

The aim of this study was evaluating the effects of different feed additives on performance of yearling bulls fed a high forage diet. One hundred and sixty-four Nellore (Bos indicus) yearling bulls were assigned to a complete randomized block design, according to of their initial body weight (BW) (298.95 ± 2.49; 10 pen/treatment; 4 animal/pen). Yearling bulls were fed daily and diets were composed of 96% of coastcross haylage and 4% of ground corn, used as the delivery vehicle for the additives. Once a day, the concentrate and forage were offered separately. The forage was offered after the entire consumption of the concentrate. The experimental diets consisted in: CON = Control (no feed additive); FLA = 3ppm of Flavomycin; NAR = 13ppm of Narasin; SAL = 20ppm of Salinomycin. The experimental period lasted 140 d and the yearling bulls were weighted at 0, 28, 56, 84, 112 and 140 d, after a 14h feed and water restriction. The orts were recorded to determine the dry matter intake (DMI). All data were analyzed using the MIXED procedure of SAS and the LSMEANS option was used to generate individual means. Tukey test 5% was used for comparisons. There was a treatment effect on DMI (CON: 6.59b; FLA: 6.53b; NAR: 7.1a; SAL: 6.42b kg/d; SEM = 0.19; P < 0.01), ADG (CON: 0.792b; FLA: 0.842b; NAR: 0.907a; SAL: 0.813b kg; SEM = 0.02; P < 0.01) and final BW (CON: 408.27b; FLA: 411.36b; NAR: 424.69a; SAL: 407.91b kg; SEM = 2.56; P < 0.01). There was no effect on feed efficiency (P = 0.41). In summary, the narasin inclusion increased DMI, ADG, and final BW in comparison with the other additives.

This study aimed to determine whether reproductive performance of ewes submitted to laparoscopic timed artificial insemination (TAI) would be similar to ante meridiem (AM)/post meridiem (PM) rule and assisted natural mating (NM), and whether GnRH may enhance the pregnancy rate in TAI. In experiment I, 191 non-lactating ewes were synchronized, then TAI was performed either 48 h after progesterone (P4) removal (TAI-48 h) or 12 h after estrus detection (AM/PM); moreover, some ewes were submitted to NM (NM) as control treatment. In experiment II, 247 non-lactating ewes were allocated in five treatments, a control (no-GnRH on protocol) and four treatments arranged in a factorial design 2 × 2. The factors were time and dose of GnRH: ewes that received either 10 μg (TAI-10 μg-36 h) or 25 μg of GnRH (TAI-25 μg-36 h) 36 h after P4 removal and ewes that received either 10 μg (TAI-10 μg-48 h) or 25 μg of GnRH (TAI-25 μg-48 h) at time of insemination, 48 h after P4 removal. In experiment I, pregnancy rate in TAI-48 h was lower (P = 0.03) than AM/PM and NM. Moreover, the probability of pregnancy in TAI-48 h was higher (P = 0.06) in ewes detected in estrus early. In experiment II, the use of GnRH in TAI protocols increased (P

The aim of this study was to evaluate the reproductive performance of 411 Nellore cows (198 nulliparous, 80 primiparous, and 133 multiparous) submitted to the 5dCO-Synch + P4 or 7dEB + P4 systems. The 5dCO-Synch + P4 system consisted of insertion of an intravaginal progesterone (P4) insert and 100 μg of GnRH (intramuscularly [i.m.]) on Day 0. On Day 5, the P4 insert was removed, and two doses of 25 mg of PGF2α (i.m.) were administered 6 hours apart. Cows not detected in estrus until 55 hours after insert removal received 100 μg of GnRH i.m. 17 hours later (i.e., 72 hours after P4 removal). The 7dEB + P4 system consisted of insertion of a P4 insert and 2 mg of estradiol benzoate (i.m.) on Day 0. On Day 7, the P4 insert was removed and 25 mg of PGF2α, 0.6 mg of estradiol cypionate, and 300 IU of eCG were administered i.m. In both systems, artificial insemination (AI) was performed according to estrus detection (i.e., cows detected in estrus until 55 hours after insert removal were inseminated at 55 hours and cows detected in estrus later or those not detected in estrus were inseminated at 72 hours). Estrus-detection risk was greater (P