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.
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 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.
The objective of this trial was to determine the effect of narasin inclusion into a protein supplement on the performance of grazing yearling bulls. One hundred and fifty Nellore yearling bulls were blocked by initial BW (332 ± 3.4 kg) and assigned to 30 paddocks (15 paddocks/treatment). Sixty paddocks of Brachiaria brizantha with 1 ha each were used, whereas each paddock was continuously grazed by 28 d, followed by a resting period of 28 d. Paddocks were rotated among treatments every 28 d to minimize possible paddock variation. The experimental period lasted 112 d, divided into 4 periods of 28 d each. The treatments were: 1) negative control (no narasin: 0N), and 2) 13 ppm of narasin/d (13N; Zimprova®; Elanco, São Paulo, Brazil). Narasin was added to the protein supplement by adjusting its concentration in each 28-d period, according to the supplement intake (SI) during the previous period. The SI was evaluated on a weekly basis. Forage mass in the paddocks was measured by choosing two points upon entry and exit of the lot from each pasture. All data were analyzed using the PROC MIXED procedure of SAS. The ADG and SI were analyzed as repeated measures over time. There was no treatment × period interaction for ADG (P = 0.06) and SI (P = 0.66). Narasin inclusion into the protein supplement did not affect SI (0N = 435.5, 13N = 431.3 g/d; SEM = 12.2; P = 0.74), increased the ADG (0N = 0.240, 13N = 0.284 kg; SEM = 0.017; P < 0.01) and the final BW of the yearling bulls (0N = 357.7, 13N = 363.0 kg; SEM = 3.43; P < 0.01). In conclusion, narasin inclusion into protein supplement improved the performance of grazing yearling bulls.
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.
RESUMO.-[Perfil metabólico ruminal e pH abomasal em ovinos tratados com ranitidina por via intravenosa.] A ovinocultura brasileira tem se intensificado, o que predispõe os animais à maior incidência de transtornos digestivos, como a úlcera de abomaso. A ranitidina é utilizada na prevenção e tratamento desta afecção, no entanto há pouca informação sobre a indicação parenteral deste fármaco para ruminantes adultos. São escassas as informações a respeito das alterações metabólicas e do comportamento do sistema digestório associados ao seu uso. Para este estudo foram utilizados cinco ovinos, machos, hígidos, providos de cânula ruminal e abomasal. O delineamento foi Quadrado Latino 5x5 com arranjo fatorial de tratamentos 2x2+1. Os ovinos tratados com as doses de 1 e 2mg/kg de ranitidina administrada por via intravenosa a cada 8 ou 12 horas foram comparados aos animais do grupo controle, Brazilian sheep production has intensified, predisposing sheep to an increased incidence of digestive disorders, such as abomasal ulcers. Ranitidine is used to prevent and treat this disease; however, there is little information on the parenteral use of this drug in adult ruminants. Few data exist on the concomitant metabolic changes and the behavior of the digestive system associated with its use. For this study, five healthy male sheep with ruminal and abomasal cannulas were used. A 5x5 Latin square experiment with a 2x2+1 factorial arrangement of the treatments was performed. Sheep treated with drug doses of 1 or 2mg/kg ranitidine administered intravenously every 8 or 12 hours were compared with the control group, was treated intravenously with 1 mL of physiological solution per 25 kg every 12 hours. Higher total protein concentrations, hemoglobin levels, as well as increased aspartate aminotransferase activity and increased abomasal pH for up to 150 min following drug administration were observed in all animals that received the drug, regardless of dose and frequency. The animals treated every 12 hours showed a decrease in leukocyte number compared with the control group and with the animals treated every 8 hours. Increased serum creatinine concentrations were observed in the animals treated every 8 hours. Treatments of 1mg/kg every 8 hours and 2mg/kg every 12 hours increased the red blood cell count and decreased the serum pepsinogen. All protocols studied were safe for healthy sheep, but 1mg/kg ranitidine every 8 hours and 2mg/kg ranitidine every 12 hours were the most effective protocols for gastric protection.
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