Objetivou-se com este trabalho avaliar a taxa de lotação e a produção de leite de vacas mestiças Holandês x Zebu em pastagens de Tifton 85 irrigadas e em sequeiro, em Uberaba-MG. Os dados foram analisados em um delineamento de blocos inteiramente ao acaso, com três repetições por tratamento, num esquema fatorial 2x10 (dois tratamentos e 10 épocas). Foi utilizado um lote de 11 vacas em lactação por tratamento para avaliação do desempenho animal. As médias foram comparadas por meio do teste de Scott-Knott ao nível de 5% de probabilidade (P<0,05). A pastagem foi manejada em sistema de pastejo rotacionado com três e cinco dias de ocupação e 21 e 35 dias de descanso no período das águas e da seca, respectivamente. A taxa de lotação média do sistema irrigado, no período avaliado, foi de 4,6 UA.ha-1, valor superior (P<0,05) à taxa média de 2,2 UA.ha-1 observada para o sistema de sequeiro. Não houve diferenças nas produções diárias de leite das vacas (P<0,05). A produção de leite média obtida no sistema irrigado foi de 51,7 litros. ha-1.dia-1. A irrigação possibilitou uma considerável intensificação do sistema, na medida em que proporcionou uma taxa de lotação bastante superior ao sistema de sequeiro.

2020) Effect of tannins and monensin on feeding behaviour, feed intake, digestive parameters and microbial efficiency of nellore cowsABSTRACT This study aimed to evaluate the associative effect of monensin and tannins on intake, feeding behaviour, digestibility, rumen kinetics, microbial protein synthesis and nitrogen balance. In a 2 Â 4 factorial arrangement, 8 rumen cannulated Nellore cows were distributed in 2 contemporary 4 Â 4 Latin squares and received 8 diets that differed in the level of tannins (0.00, 0.75, 1.50 and 2.25% DM) and presence of monensin. Monensin was daily administered to each cow in one square (about 32 mg/kg DM). No interaction between monensin and tannins was observed (p > .05). Tannins linearly reduced feed intake, but linearly increased daily eating time (p < .05), although these did not alter the number of meals. Monensin increased CP digestibility by 6% (p ¼ .0387) while tannins linearly reduced digestibility of DM, CP, OM and TDN, whereas the reduction was quadratic for ADF and NDF. Tannins linearly reduced the rumen disappearance rate by linearly reducing both passage and digestion rates. Tannins also linearly reduced urinary urea, though neither additive affected microbial protein synthesis. Monensin reduced the proportion of N excreted in faeces, whereas tannins linearly increased faecal N and linearly reduced both urinary and retained N. Monensin and tannins have shown independent effects on feeding behaviour, feed intake, digestive parameters, microbial protein synthesis and N balance, but they did not improve nutrient usage, although monensin alone has shown to have potential to promote N utilisation. Tannins may play an important role in reducing the excretion of N in urine. HIGHLIGHTSTannins reduce the efficiency of nutrient usage in cattle. Tannins change the pathway of the excretion of the feeding nitrogen. The emission of N 2 O from the urine may be reduced by the use of tannins in cattle feeding. ARTICLE HISTORYpromoting the production of propionate (Duffield et al., 2008a). This may alter the feeding behaviour and reduce DMI by a metabolic-feedback effect. The meta-analysis of Duffield et al. (2012) shows that monensin reduces DMI and improves average daily gain through improvement of feed efficiency. But other studies, such as of Hamilton et al. (2010), Mullins et al. (2012) and Perna Junior et al. (2017 found no effect, suggesting that the effect may vary among studies. Monensin also reduces rumen protein digestion with a consequent reduction of rumen ammonia production CONTACT Dr.

This study aimed to evaluate the effects of immunocastration on the performance, testosterone concentration, carcass traits and meat quality of feedlot-finished Nellore cattle. Fifty-eight males (430 ± 36 kg bodyweight; 24 months old) were separated into three groups in a randomised complete design: surgically castration (n = 15), immunocastrated (anti-gonadotropin-releasing hormone (Bopriva®) vaccine, n = 21) and non-castrated (n = 22). The animals were housed in individual pens and fed ad libitum for 90 days with a common diet comprising 70% concentrate and 30% roughage (corn silage). The non-castrated animals had a greater average daily gain, feed efficiency, hot carcass weight and carcass yield than the surgically castrated and immunocastrated animals (P &lt; 0.05). Surgically castrated cattle grew faster and more efficiently than those castrated immunologically (P &lt; 0.05). The surgically castrated and immunocastrated animals had higher colour values L*, a* and b* and cooking loss than non-castrated animals (P &lt; 0.05). In conclusion, immunocastration decreased cattle performance compared with surgically castrated or non-castrated animals. However, immunocastration resulted in better meat quality compared with non-castrated, making it an alternative to surgical castration with no negative effects on animal welfare.

SENE, G.A. Organic additives for cattle fed high concentrate diets. 2017. 65f.

No abstract

Aimed to evaluate the association between essential oils (Next Enhance 300®), exogenous enzymes (Allzyme SSF®), and monensin for the rumen fermentation manipulation, especially reduction of rumen methane in Nellore cattle. Eight cows weighing 480 ± 55 kg and cannulated in the rumen were used in two 4x4 Latin squares, into a 2x2x2 factorial arrangement, which one of the factors being analyzed by the squared effect. The animals fed the same basal diet using a corn silage: concentrate ratio of 60:40. The factors used were: 300 mg/animal/d, 10 g/animal/d, 300 mg/animal/d for essential oils, exogenous enzyme, and monensin, respectively. Each experimental period lasted 26 days. Sixteen days were used for adaptation to the experimental diets, while from D16 to D21 for evaluation of DMI and D22 to evaluate rumen fermentation (0, 3, 6, 9, and 12h after feeding) through the ex situ technique, which consists of incubating ruminal content in conditions similar to those of the rumen allowing the measurement of rumen production (SCFA and methane). Differences were considered significant when P-value was below 0,05 through analysis of variance using mixed procedure. No significant difference (P &gt; 0.05) was observed for DMI Monensin decreased (P &lt; 0.05) the concentration of acetic, butyric and total SCFA. However, the production of acetic acid, propionic acid, total SCFA and acetate:propionate ratio was not altered (P &gt; 0,05). Significant interaction (P &lt; 0.05) between enzyme and monensin was observed for butyric acid production, indicating the enzyme used alone did not alter the production of these acid, but when associated with monensin, a reduction was observed. The enzyme reduced (P &lt; 0.05) methane concentration, and when associated with monensin this reduction was increased. However methane production was not affected (P &gt; 0.05). The feed additives evaluated do not reduce the rumen production of methane, but reduced butyric acid production.

This study aimed to evaluate the use of essential oils, exogenous enzymes, sodium monensin, and their associations as a nutritional strategy to mitigate ruminal CH4 emissions from Nellore cows and their impacts on the anaerobic biodigestion of manure.The thesis was structured in two studies. In study 1, eight cannulated Nellore cows (480 ± 55 kg) were used, distributed in a duplicated 4 x 4 Latin square design, in a 2 x 2 x 2 factorial scheme (4 periods of 28 days) totaling 4 repetitions (32 experimental units). The animals received a basal diet composed of 60% corn silage and 40% concentrate, with the daily supply being adjusted as a function of DMI. The factors were composed by the presence or absence of exogenous enzyme (1027 mg/kg DM), essential oil (31.7 mg/kg DM), and monensin (30.6 mg/kg DM) in the diet. Data were analyzed using SAS PROC MIXED and differences were declared significant at 5%. The association between the additives promoted alterations in the DMI, being antagonistic on the microbial efficiency, on the digestible energy lost in the form of ruminal CH4, and on the gross energy released in the intestine. However, no associative effects were observed between the additives on the production of SCFA. In study 2, experimental anaerobic batch-type biodigesters were used in a completely randomized design (32 experimental units) to evaluate the anaerobic biodigestion of waste from Nellore cows fed with sodium monensin, exogenous enzyme, essential oil, and their combinations. Data were also analyzed using SAS PROC MIXED and differences were declared significant at 5%. The association between the tested additives did not change the biodigestion process, however, the use of sodium monensin has been shown to reduce the biogas production potency and the concentration of nutrients in the biofertilizer. Thus, the association between the tested additives as a nutritional strategy did not prove to be able to reduce ruminal CH4 emissions, with no effect on the anaerobic biodigestion of manure.

The objective of this experiment was to evaluate the association between different feed additives on ruminal fermentation parameters especially ruminal methane on cannulated beef cattle. Five Nellore cows, 480 ± 55 kg, ruminally cannulated were used. The experimental was a 5 x 5 Latin square design and the experimental unit was the animal within each period (n = 25 experimental units). The diets offered differed only by the inclusion or not of monensin, calcium nitrate or tannin, totaling five treatments: Control (without addition of additives), Monensin (30 ppm in the diet), Nitrate (3.0% of DM), Tannin (1.5% of DM) and Pool (combination of the three additives), being supplied in a basal diet with a concentrate: roughage (corn silage) ratio of 60:40. The study was divided into five periods, each one with 26 days. Sixteen days were used for adaptation to the experimental diets; ruminal fluid samples were collected at 0, 3, 6, 9 and 12h after feeding at 22nd day. To evaluate CH4 production and ammoniacal nitrogen balance, samples were incubated ex situ on equality ruminal conditions and then analyzed by gas chromatography and UV spectrophotometric, respectively. Data were analyzed using PROC MIXED of SAS and differences were declared significant at 5%. There was interaction between sampling time and treatment (P &lt; 0001) and all the additives were efficient in decreasing the methane production in mol/g/hour (P &lt; 0001), mol/kg/day (P &lt; 0001) and g/kg/day (P &lt; 0001). Comparing to the Control all additives decreased CH4 production, and decreases were 9.5% for monensin, 18.75% for tannin, 19.8% for calcium nitrate and 28.8% for the Pool (monensin, nitrate and tannin). Concentration and balance of rumen NH3-N was not affected by any treatments. It was possible to conclude that association of additives of different mechanism of action presented a partial additive effect.