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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)

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.

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.

The objective of this study was to determine the effects of narasin on rumen fermentation of steers fed a high-forage diet. Thirty rumen-fistulated Nellore steers were assigned to a randomized completed block design, defined by initial BW. Steers were fed daily and diets were composed of 99% of coastcross haylage and 1% of concentrate, used as delivery vehicle for the narasin. The concentrate was offered separately, and the forage was offered after the total consumption of concentrate. The experimental diets were: N0 = concentrate without narasin; N13: inclusion of 13 ppm of narasin; and N20 = inclusion of 20 ppm of narasin. The trial lasted 140 days, divided on 5 periods of 28 days each. Rumen fluid was collected on days 0, 28, 56, 84, 112 and 140, starting 6 hours after feeding, in order to evaluate rumen pH and SCFA. Data were analyzed as repeated measures over time using the MIXED procedure of SAS and the LSMEANS option was used to generate individual means. Data obtained on d 0 were used as covariate. Orthogonal polynomials were determined by linear and quadratic effect. There was no treatment and day interaction for any of the parameters evaluated (P > 0.05). There was a quadratic effect on acetate (73.9, 72.6, and 72.6 mM/100mM; P < 0.01), propionate (13.9, 15.9, and 15.3 mM/100mM; P < 0.01), butyrate (9.1, 8.7, and 9.0 mM/100mM; P < 0.01), valerate (1.0, 0.9, and 1.0 mM/100mM; P = 0.01), and Ac:Pr ratio (5.3, 4.6, and 4.8; P < 0.01). The narasin inclusion linearly increased total SCFA (93.1, 98.9, and 104.4 mM; P < 0.01), whereas no effects were noted on rumen pH (6.69 ± 0.05; P = 0.23). Hence, the inclusion of 13 ppm of narasin increased propionate and decreased the Ac:Pr ratio. Key Words

Narasin is a coccidiostatic and antibacterial agent that may change rumen fermentation, improving ruminants performance. The objective of this trial was evaluate the effects of narasin inclusion on diets over the milk production and composition of ewes, and performance of their lambs. Thirty lactating ewes were allotted in a randomized complete block design, defined by body weight, offspring number and sex. Diets were formulated to be isonitrogenous (14% CP, DM basis), composed of 50% coastcross hay and 50% concentrate, fed once a day, ad libitum. The treatments were determined by no inclusion (N0) or inclusion of 13 ppm of narasin (N13). From the 2nd until the 10th week of lactation, DMI was measured, whereas in the same period, once a week, the ewes were separated from their lambs, and mechanically milked after intravenous administration of 10 IU of synthetic oxytocin. Three hours after the first milking, the ewes were milked again for milk production and composition evaluation. Data were analyzed as repeated measures over time using the MIXED procedure of SAS and the LSMEANS option was used to obtain the means. Narasin did not affect DMI (2.52 for N0 and 2.71 kg/d for N13 [SEM 0.10, P = 0.16]), however, it increased milk production (153.69 for N0 and 187.83 g/3h for N13 [SEM 12.43, P = 0.04]). Narasin supplementation decreased protein concentration (5.41 for N0 and 5.07% for N13 [SEM 0.09, P < 0.01]), but had no effect on fat, lactose and total solids composition (%, p > 0.05), or fat, protein, lactose and total solids production (g/3h, p > 0.05). In conclusion, narasin administration at 13 ppm improved the lactation performance in ewes offered a 50 % concentrate diet.

The aim of this study was to determine the effects of three additives (Narasin, Lasalocid and Virginiamycin) on rumen fermentation characteristics of steers fed high-forage diet. Thirty-two rumen-fistulated Nellore steers were assigned to a randomized completed block design, according to their initial BW. Steers were fed daily and diets were composed of 99% of coastcross haylage and 1% of concentrate, used as delivery vehicle for the additives. The concentrate and forage were offered separately, whereas the forage was offered after the entire consumption of the concentrate. The experimental diets consisted of: CON = Control; NAR: 13 ppm of narasin; LAS = 20 ppm of lasalocid; and VIR: 20 ppm of virginiamycin. 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 as repeated measures over time using the MIXED procedure of SAS and the LSMEANS option was used to generate individual means. Data obtained on d 0 were used as covariate. Orthogonal contrasts were determined to mean comparisons (C1: CON vs NAR, LAS, VIR; C2: NAR and LAS vs VIR; C3: NAR vs LAS). There was a treatment effect on total SCFA (87.13, 105.42, 88.64 and 90.35 mM/100mM; C1: P = 0.02; C2: 0.06; C3: P < 0.01), propionate (14.47, 15.74, 14,77 and 14,50 mM/100mM; C1: P = 0.04; C2: P = 0.01; C3: P < 0.01), and Ac:Pr ratio (5.19, 4.50, 5.05 and 5.23; C1: P < 0.01; C2: P < 0.01; C3: P < 0.01). Therefore, the inclusion of narasin increased propionate, total SCFA and decreased the Ac:Pr ratio compared to the other feed additives.

The objective in this trial was to determine the effects of partial replacement of ground corn by citrus pulp or soybean hulls on performance and carcass characteristics of feedlot goat kids. Twenty one Boer x Saanen kids (initial BW 15.8 ± 0.7kg), nine males and 12 females, were distributed in a complete randomized block design, according to sex and initial body weight. Treatments were set by replacing 50% of ground corn (DM basis) for citrus pulp or soybean hulls; whereas, forage concentrate ratio was of 10:90. Partial replacement of corn by citrus pulp or soybean hulls increased dry matter intake, average daily gain and final body weight, but feed efficiency was not affected. There was no difference between citrus pulp or soybean hulls. Inclusion of coproducts increased slaughter weight, hot and cold carcass weight and longissimus muscle area, with no difference between citrus pulp and soybean hulls. Subcutaneous fat thickness, hot and cold carcass yields, shrink after chilling and body wall thickness were not affected by treatments. Citrus pulp and soybean hulls can replace 50% of ground corn (DM basis) increasing dry matter intake and weight gain in goat kids enabling higher slaughter weight at earlier age. RESUMO: O objetivo neste estudo foi avaliar a substituição parcial do milho pela polpa cítrica (PC) ou casca de soja (CS) sobre o desempenho e as características de carcaça de cabritos confinados. Foram utilizados 21 cabritos Boer x Saanen (PC inicial de 15,8±0,7kg), sendo nove machos e 12 fêmeas, distribuídos em delineamento experimental de blocos completos casualizados (7 blocos e 3 tratamentos). Os tratamentos foram definidos pela substituição de 50% do milho pela PC ou CS (% da MS). As dietas continham 90% de concentrado e 10% de volumoso. A substituição parcial do milho pela PC ou CS aumentou o consumo de matéria seca (CMS), o ganho médio diário de peso corporal (GMD) e o peso corporal final, porém a eficiência alimentar não foi alterada. A inclusão dos coprodutos aumentou o peso corporal ao abate (PCA), o peso de carcaça quente (PCQ) e fria (PCF) e a área de olho de lombo (AOL). Não houve diferença entre os coprodutos com relação ao desempenho e às características de carcaça. A substituição de 50% do milho (64,2% de MS) pela polpa cítrica ou casca de soja, em dietas com alto concentrado, aumenta o consumo de matéria seca e o ganho médio diário de peso dos cabritos, possibilitando maior peso ao abate com idade menor.