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This study evaluated different herbage allowances from mid to late pregnancy on pre- and postpartum physiological responses, milk production, and the performance of Nellore cows and the preweaning growth of their female offspring. Sixty multiparous Nellore cows were blocked by their body weight (BW; 425 ± 36 kg) and body condition score (BCS; 3.67 ± 0.23, scale 1-5) and randomly allocated to twelve pastures. Treatments consisted of two different herbage allowances (HA) during pregnancy: low HA (LHA; 2.80 kg DM/kg of BW) and high HA (HHA; 7.60 kg DM/kg of BW). Both treatment groups were fed 1 g/kg BW of a protein supplement. After calving, all cow-calf pairs were combined in a single group. The effects of maternal treatment × day of the study were detected for herbage mass and allowance, the stocking rate and forage crude protein, and for cow BW, BCS, and carcass measures (p < 0.01). Milk yield corrected to 4% fat, while the levels of fat total solids and cow plasma IGF-1 and urea were different (p ≤ 0.04) between treatments. HHA offspring was heavier (p ≤ 0.05) at 120 days and at weaning. A high herbage allowance can be implemented from mid-gestation until calving to increase cow prepartum performance, post-partum milk yield and composition, and positively modulate female offspring preweaning growth.

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Two studies evaluated the productive characteristics of young Nellore heifers receiving different days on feed (DOF) to determine the biological slaughter endpoint. In Experiment 1 (Exp. 1), fifty-one Nellore heifers [324 ± 19.3 kg of body weight (BW); 16 ± 1 months] were split into three DOF lengths (45, 75, or 105 days), while in Experiment 2 (Exp. 2), thirty-six Nellore heifers (362 ± 25.5 kg of BW; 18 ± 1 months of age) were split into three DOF lengths (45, 90, or 135 days). In both studies, all animals were distributed in complete randomized blocks according to initial BW and stratified via carcass ultrasound. The diet was supplied ad libitum, allowing 3% of refusals. The point at which the animals achieved 25% of ether extract of shrunk body weight (EESBW) was defined as the biological endpoint. Thus, relationships were made between some characteristics obtained in both studies. Positive linear relationships were found between backfat thickness (BFT) vs. EESBW (p < 0.001, r = 0.84) and BFT vs. body weight (p < 0.001, r = 0.77). Our results suggest that the biological slaughter endpoint for young Nellore heifers is 6.97 mm of backfat thickness or 402 kg shrunk body weight, corresponding to around 75 DOF.

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The objective of this study was to evaluate the effect of the use of post-ruminal urea on performance, nitrogen metabolism and the ruminal environment of Nellore cattle reared on pasture during the dry season. In experiment 1 (Exp. 1), nine ruminal-cannulated Nellore steers, 30 ± 2 months old (651 ± 45 kg body weight (BW)), were allotted to a 3 × 3 Latin triple square. In experiment 2 (Exp. 2), 84 Nellore bulls, 18 ± 3 months old (315 ± 84 kg BW), were distributed in complete randomized blocks, by initial BW. Protein supplements were supplied daily, in the amount of 2 g/kg BW, and consisted of either CONT: protein + conventional urea (50% CP), PRU: protein + post ruminal urea (50% CP) and U + PRU: protein + urea conventional + post-ruminal urea (70% CP). The paddocks were composed of Urochloa brizantha cv. Marandu grass. In Exp. 1, there was no treatment effect for DM, OM, NDF, forage intake, and CP, but there was a higher intake for PRU (p < 0.005) and a higher digestibility for U+ PRU (p = 0.001). There was no effect on ruminal pH or NH3-N concentration (p ≥ 0.232), but there was an interaction between treatment and time for them (p < 0.039). Furthermore, there was a treatment effect on the total SCFA concentration, with CONT being higher than the others. A difference in the acetate:propionate ratio was found (p < 0.027), with a greater relationship for PRU and U + PRU. A treatment effect (p = 0.049) was found for the propionate proportion, with a higher proportion in the CONT. Nitrogen intake was consequently lower for the CONT and higher urinary excretion for the U + PRU (p = 0.002). Animals supplemented with CONT showed a tendency to have more Bacteria and fewer Archaea (p = 0.086). In Exp. 2, there was a treatment effect for the disappearance rate of the supplement (p < 0.001). Intake was faster for PRU and CONT, but performance was not affected by PRU (p = 0.311). The use of post-ruminal urea alters the microbial population, but does not affect performance. Therefore, supplementation with post-ruminal urea presented similar results compared to conventional urea. Ruminal and blood parameters and animal performance were not influenced by treatments.

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The objective was to evaluate the effects of urea with post-ruminal absorption in the supplementation of growing Nellore cattle reared on pasture during a seasonal period. For the study, two experiments were conducted. In experiment 1, rumen and blood parameters were evaluated using eight rumen-cannulated Nellore bulls with initial body weight (BW) of 763 ± 44 kg, distributed in a double Latin square 4 × 4. In experiment 2, 120 Nellore steers with initial BW of 380 ± 35 kg were used for performance evaluation, distributed in a randomized block design (blocking factor or initial BW). The evaluated treatments were 1: (TP-U) (control) = supplement with 24% crude protein (CP) containing urea as a source of non-protein nitrogen (NPN; 3%) and soybean meal, 2: (TP-PRU) = 24% CP supplement containing post-ruminal urea (PRU; 3.6%) and soybean meal; 3: (NPN-U-PRU) = 24% CP supplement containing urea + post-ruminal urea (U = 3% and PRU = 3.9%), without soybean meal; 4: (NPN-PRU) = supplement with 24% CP containing post-ruminal urea (7.5%), without soybean meal. The supplement was offered at 3 g/kg BW per animal, daily, once a day. All animals were kept on Urochloa brizantha cv. Marandu pasture. Statistical analyses were performed using the SAS PROC MIXED, and the data were evaluated by the following contrasts: C1 = TP-U/TP-PRU vs. NPN-U-PRU/NPN-PRU (Soybean meal replacement by NPN); C2 = TP-U vs. TP-PRU (conventional urea vs. post-immune urea); C3 = NPN-U-PRU vs. NPN-PRU (low and high post-ruminal urea-PRU level). The digestibility of dry matter, organic matter, and NDF was lower when soybean meal was replaced by non-protein nitrogen, also being different between the levels of post-ruminal urea used in the supplement. Ruminal pH was different when soybean meal was replaced by NPN (p = 0.003). Total concentration of short-chain fatty acids, concentrations of isobutyrate (p = 0.003), valerate (p = 0.001), and isovalerate (p = 0.001) were different, and blood urea was different when soybean meal was replaced by NPN (p = 0.006). Simpson's diversity index was higher in the rumen of animals supplemented with TP-U than in those supplemented with TP-PRU (p = 0.05). A total of 27 phyla, 234 families, and 488 genera were identified. Nitrospirota and Gemmatimonadota phyla were detected just in the rumen of steers supplemented with TP-PRU. The performance (final BW, weight gain and gain per area) of the animals was different, being higher (p = 0.04) in animals supplemented with soybean meal, compared to NPN. The removal of soybean meal from the supplement and its replacement with either conventional urea plus post-ruminal urea or only post-ruminal urea compromises the performance of the animals. The lower the post-ruminal urea inclusion level, the lower the apparent digestibility of dry matter, organic matter, and NDF, when compared to animals supplemented with higher levels.

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This study evaluated the effects of pelleted citrus pulp (PCP) added to orange peel on fermentative parameters and aerobic stability of orange peel silages. The treatments were based on different levels of PCP: 0 (control), 10% PCP, 20% PCP, and 30% PCP calculated according to the weight of orange peel (w/w), with five experimental silos per treatment stored for 60 days. Chemical composition, fermentative parameters, microbial population, and dry matter (DM) losses were performed in silages after opening the experimental silos. Furthermore, aerobic stability was evaluated for 12 days. Silages with 10 and 20% PCP presented suitable levels of DM, 226 and 302 g kg−1, respectively, and probably adequate water activity that benefited the lactic acid fermentation, but it jeopardized their aerobic stabilities. The inclusion of 10% PCP did not reduce the effluent loss compared with the control silages. Yet, 30% PCP silage showed the lowest effluent loss (93%), in contrast to the low lactic acid content (35 g kg−1) and short aerobic stability (49 h). Control silages remained stable for a longer period (115 h), but showed greater loss of N as NH3, and higher losses of DM through gas (354 g kg−1) and effluents (114 g kg−1). In short, we highlighted 20% PCP silage because of its high lactic acid bacteria (6.3 cfu g−1), high lactic acid:acetic acid ratio (1.41), low nitrogen degradation as NH3, and reduced gas (67%) and effluent (80%) productions. With the highest lactic acid (66.42 g kg−1), these well-preserved silages showed a more intense aerobic degradation, starting after 42h. The inclusion of PCP to orange peel improves the fermentation process probably due to the decrease of water activity, but decreases the aerobic stability of the silage as well.(AU)

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[This corrects the article DOI: 10.3389/fmicb.2019.00614.].

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This study investigated the long-term effects (13 months) of encapsulated nitrate supplementation (ENS) on enteric methane emissions, rumen fermentation parameters, ruminal bacteria, and diversity of archaea in grazing beef cattle. We used a total of thirty-two Nellore steers (initial BW of 197 ± 15.3 kg), 12 of which were fitted with rumen cannulas. For 13 months, the animals were maintained in 12 paddocks and fed a concentrate of ground corn, soybean meals, mineral supplements, and urea (URS) or encapsulated nitrate (EN) containing 70 g of EN/100 kg of BW (corresponding to 47 g NO3 -/100 kg BW). Encapsulated nitrate supplementation resulted in similar forage, supplement and total DMI values as URS (P > 0.05), but ENS tended to increase (+48 g/d; P = 0.055) average daily weight gain. Daily reductions in methane emissions (-9.54 g or 18.5%) were observed with ENS when expressed as g of CH4/kg of forage dry matter intake (fDMI) (P = 0.037). Lower concentrations of NH3-N and a higher ruminal pH were observed in ENS groups 6 h after supplementation (P < 0.05). Total VFA rumen concentration 6 h (P = 0.009) and 12 h after supplementation with EN resulted in lower acetate concentrations in the rumen (P = 0.041). Steers supplemented with EN had a greater ruminal abundance of Bacteroides, Barnesiella, Lactobacillus, Selenomonas, Veillonella, Succinimonas, Succinivibrio, and Duganella sp. (P < 0.05), but a lower abundance of Methanobrevibacter sp. (P = 0.007). Strong negative correlations were found between daily methane emissions and Proteobacteria, Erysipelotrichaceae, Prevotellaceae, and Roseburia, Kandleria, Selenomonas, Veillonella, and Succinivibrio sp. (P < 0.05) in the rumen of ENS steers. Encapsulated nitrate is a feed additive that persistently affects enteric methane emission in grazing steers, thereby decreasing Methanobrevibacter abundance in the rumen. In addition, ENS can promote fumarate-reducer and lactate-producer bacteria, thereby reducing acetate production during rumen fermentation.

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The objective of this survey was to identify what mycotoxins were present in ingredients used in diets offered to beef cattle in feedlots and their concentrations. The survey covered 30 Brazilian feedlots located in the five major beef-producing states. Samples of total mixed ration (TMR) and ingredients were collected and analyzed for mycotoxin using ultra-performance liquid chromatography coupled to tandem mass spectrometry. Mycotoxin concentrations were further interpreted according to known species-specific sensitivities and normalized according to the principles of toxic equivalent factors (risk equivalent quantities - REQ) expressed in µg kg−1 of aflatoxin B1-equivalent. Forty percent of the visited feedlots had apparent fungi in TMR. However, only one feedlot (3%) used a mycotoxin adsorbent. On the other hand, diets with high contamination presented no apparent fungi. One hundred percent of TMR was contaminated. All samples presented at least one mycotoxin contamination, with 65.5% considered low contamination, 27.6% medium contamination, and 6.90% high contamination. The toxins identified in TMR were fumonisins (most frequently), trichothecenes A, trichothecenes B, fusaric acid, aflatoxins, and ergot (mean concentration values: 2,330, 104.3, 79.5, 105, 10.5, and 5.5 µg kg−1, respectively). According to the contamination of TMR samples per region, Mato Grosso do Sul state presented the highest contaminations. Peanut meal was the most contaminated ingredient. One hundred percent of TMR in Brazilian feedlot is contaminated. Fumonisins were the mycotoxin most frequent and at highest concentrations in TMR samples. Moreover, mycotoxin concentrations have a distinct pattern among ingredients, TMR, and feedlots (local).(AU)

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There are no studies evaluating the virginiamycin (VM) doses under tropical conditions. So, the present study was conducted to evaluate the optimal dose of VM for growing Nellore bulls on tropical pasture. Two experiments were conducted. The first experiment, one hundred and two Nellore bulls (307 ± 25 kg body weight [BW]; 22 months) were used. Animal performance was evaluated using a randomized block design, with group as experimental unit (n = 8; 12 animals each). The second experiment, a double 4 × 4 Latin square, eight animals were used to evaluate the ruminal parameters. Four doses were evaluated: 0, 35, 55, and 75 mg VM per 100 kg BW. The average daily gain (P = 0.08) and carcass gain (P = 0.05) exhibited a trend of quadratic behavior. An increased dose of VM did not affect supplement intake (P = 0.64), rumen pH (P = 0.96), acetate: propionate ratio (P = 0.73), or the total concentration of volatile fatty acid (P = 0.63). The concentration of rumen ammonia nitrogen exhibited a quadratic effect (P = 0.01). A quadratic behavior was found for volatile fatty acid, except for propionate, which presented linear behavior (P = 0.03). In conclusion, the dose of 47 mg VM per 100 kg BW is recommend for growing Nellore bulls on tropical pasture.(AU)

Em condições tropicais não existem estudos avaliando doses de virginiamicina (VM). Dessa forma, o presente estudo foi conduzido para avaliar a dose ótima de VM para bovinos Nelore recriados em pasto tropical. Dois experimentos foram conduzidos. No Experimento 1 foram usados 102 bovinos Nelore não castrados, com peso corporal (PC) inicial de 307 ± 25 kg e 22 meses de idade. As variáveis de desempenho foram avaliadas em blocos inteiramente casualizados, sendo o grupo a unidade experimental (n = 8; 12 animais cada). No Experimento 2 foram utilizados 8 animais em quadrado latino duplo para avaliação dos parâmetros ruminais. Foram avaliadas 4 doses de VM: 0, 35, 55, e 75 mg VM para cada 100 kg PC. O ganho médio diário (P = 0.08) e o ganho em carcaça (P = 0.05) apresentaram tendência de comportamento quadrático. O aumento na dose de VM não afetou o consumo de suplemento (P = 0.64), pH ruminal (P = 0.96), relação acetato: propionato (P = 0.73) e a concentração total de ácidos graxos voláteis (P = 0.63). A concentração de nitrogênio amoniacal ruminal apresentou efeito quadrático (P = 0.01). Comportamento quadrático foi observado para todos os ácidos graxos voláteis, exceto propionato, o qual apresentou comportamento linear (P = 0.03). Em conclusão, a dose de 47 mg VM/100 kg PC é recomendada para bovinos Nelore recriados em pastos tropicais.(AU)

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There are no studies evaluating the virginiamycin (VM) doses under tropical conditions. So, the present study was conducted to evaluate the optimal dose of VM for growing Nellore bulls on tropical pasture. Two experiments were conducted. The first experiment, one hundred and two Nellore bulls (307 ± 25 kg body weight [BW]; 22 months) were used. Animal performance was evaluated using a randomized block design, with group as experimental unit (n = 8; 12 animals each). The second experiment, a double 4 × 4 Latin square, eight animals were used to evaluate the ruminal parameters. Four doses were evaluated: 0, 35, 55, and 75 mg VM per 100 kg BW. The average daily gain (P = 0.08) and carcass gain (P = 0.05) exhibited a trend of quadratic behavior. An increased dose of VM did not affect supplement intake (P = 0.64), rumen pH (P = 0.96), acetate: propionate ratio (P = 0.73), or the total concentration of volatile fatty acid (P = 0.63). The concentration of rumen ammonia nitrogen exhibited a quadratic effect (P = 0.01). A quadratic behavior was found for volatile fatty acid, except for propionate, which presented linear behavior (P = 0.03). In conclusion, the dose of 47 mg VM per 100 kg BW is recommend for growing Nellore bulls on tropical pasture.

Em condições tropicais não existem estudos avaliando doses de virginiamicina (VM). Dessa forma, o presente estudo foi conduzido para avaliar a dose ótima de VM para bovinos Nelore recriados em pasto tropical. Dois experimentos foram conduzidos. No Experimento 1 foram usados 102 bovinos Nelore não castrados, com peso corporal (PC) inicial de 307 ± 25 kg e 22 meses de idade. As variáveis de desempenho foram avaliadas em blocos inteiramente casualizados, sendo o grupo a unidade experimental (n = 8; 12 animais cada). No Experimento 2 foram utilizados 8 animais em quadrado latino duplo para avaliação dos parâmetros ruminais. Foram avaliadas 4 doses de VM: 0, 35, 55, e 75 mg VM para cada 100 kg PC. O ganho médio diário (P = 0.08) e o ganho em carcaça (P = 0.05) apresentaram tendência de comportamento quadrático. O aumento na dose de VM não afetou o consumo de suplemento (P = 0.64), pH ruminal (P = 0.96), relação acetato: propionato (P = 0.73) e a concentração total de ácidos graxos voláteis (P = 0.63). A concentração de nitrogênio amoniacal ruminal apresentou efeito quadrático (P = 0.01). Comportamento quadrático foi observado para todos os ácidos graxos voláteis, exceto propionato, o qual apresentou comportamento linear (P = 0.03). Em conclusão, a dose de 47 mg VM/100 kg PC é recomendada para bovinos Nelore recriados em pastos tropicais.

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This study evaluated the nutritional interrelationship between the growing and finishing phases of crossbred cattle in determining their performance. One hundred and eight animals were used (8 months old, body weight [BW] 211 ± 20 kg). During the dry season, the animals received one of the following supplements: a mineral plus urea supplement (ad libitum, MSD), a protein supplement (1 g/kg BW per day, PR1), or a protein-energy supplement (5 g/kg BW per day, PE). During the rainy season, the animals received one of the following supplements: a mineral without urea supplement (ad libitum, MSR), a protein supplement (1 g/kg BW per day, PR2), or PE (5 g/kg BW per day). The experimental design was completely randomized using a 3 × 3 factorial scheme (for the rainy season) and a 3 × 3 × 2 factorial scheme (for the finishing phase). The supplementation and finishing systems were considered to be the treatments, and the animals were considered to be the experimental units. Dry season supplementation did not affect the average daily gain (ADG) during the rainy season (P = 0.12) or the finishing phase (P = 0.73). An increase in the level of rainy season supplementation reduced ADG by 12% during the finishing phase (P < 0.06). Providing PE during the dry and rainy seasons led to the animals being slaughtered 17 (P = 0.06) and 30 (P < 0.01) days earlier, respectively. Our results indicate that supplementation during the dry season (under poor-quality pasture conditions) does not affect the performance during the rainy season or the finishing phase. Furthermore, while providing PE during the rainy season can reduce ADG during finishing, the higher BW at the beginning of the finishing phase is sufficient to reduce the time of the finishing period.

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The objective of this study was to evaluate the effect of increasing the supply of protein with different degradation rates on the performance and metabolism of growing Nellore cattle reared on Brachiaria brizantha cv. Marandu pasture during the transition period from the dry to rainy season. The experiment was installed on an area of 34 ha, divided into 12 paddocks with an average area of 2.85 ha. In the performance evaluation were utilized 72 recently weaned, non-castrated Nellore cattle with an initial body weight (BW) of 199 kg (SEM = 16). The following supplements were used: energy protein supplement containing 25% crude protein (CP) (C-25) and energy protein supplements containing 40% CP with one third highly degradable CP and two thirds poorly degradable CP (40-1/3NPN), one half highly degradable CP and one half poorly degradable CP (40-1/2NPN), and two thirds highly degradable CP and one third poorly degradable CP (40-2/3NPN). Higher protein degradation rates reduced supplement intake (P < 0.01). In the first period, animals consuming supplement 40-1/3NPN exhibited higher average daily gain (ADG) (0.30 kg/day), similar to that of animals receiving supplement 40-1/2NPN (P = 0.04). In the second period, supplement 40-2/3NPN resulted in lower ADG (0.19 kg/day less than the other supplements). There was no effect of supplement on animal performance in the third period (P > 0.10), when ADG was 0.56 kg/day. In conclusion, the response to supplementation is associated with interactions with characteristics of the forage canopy. Supplementation with a true protein source will be beneficial only during the early stage of the dry-rainy season transition period.

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This study evaluated the effect of using fresh sugar cane, sugar cane silage with or without Lactobacillus buchneri, and burnt sugar cane silage with or without L. buchneri on ingestive behavior, nitrogen balance and synthesis of microbial nitrogen compounds of dairy cows. Five ¾ Holstein x Gir crossbred cows, assigned to a 5 x 5 Latin square design, were given diets with a 60:40 forage: concentrate ratio on a dry matter basis, to meet an average body weight of 550 kg and production of 15 kg of milk per day. The treatment with fresh sugar cane showed higher values (p 0.05) for dry matter feed efficiency (3,133.3 vs 2,234.47 g DM h-1) and rumination (1,642.3 vs 1,222.93 g DM h-1) compared to the silages. There was a shorter total chewing time (58.7 vs 81.5 min. kg-1 DM) for fresh sugar cane when compared to silages without inoculum. The addition of microbial additive during ensiling of sugar cane did not alter (p > 0.05) the nitrogen intake and balance, but led to a greater (p 0.05) synthesis of microbial nitrogen. Microbial efficiency was not affected (p > 0.05), and showed an average value of 204.32 g microbial crude protein kg-1 total digestible nutrients.

Objetivou-se avaliar o efeito da utilização de cana-de-açúcar in natura, silagem de cana sem ou com Lactobacillus buchneri e cana queimada sem ou com L. buchneri sobre o comportamento ingestivo, balanço de nitrogênio e síntese de compostos nitrogenados microbianos em vacas lactantes. Foram utilizadas cinco vacas mestiças, ¾ Holandês x Gir, distribuídas em um quadrado latino 5 x 5 e alimentadas com dietas compostas por 60% de volumoso e 40% de concentrado na base da matéria seca, para atender um peso corporal médio de 550 kg e produção média de 15 kg de leite por dia. A cana-de-açúcar in natura proporcionou maiores valores (p 0,05) para eficiência de alimentação da matéria seca (3.133,3 vs 2.234,47 g MS h-1) e de ruminação (1.642,3 vs 1.222,93 g MS h-1) em relação às silagens. Observou-se menor tempo de mastigação total (58,7 vs 81,5 min. kg-1 de MS) para cana-de-açúcar in natura quando comparada às silagens sem inóculo. A utilização do aditivo microbiano na ensilagem da cana-de-açúcar não alterou (p > 0,05) o consumo e o balanço de nitrogênio, porém propiciou maior (p 0,05) síntese de nitrogênio microbiano. Não houve diferença entre as dietas (p > 0,05) para eficiência microbiana, cujo valor médio foi de 204,32 g PB microbiana kg-1 de TDN.

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This study evaluated the effect of using fresh sugar cane, sugar cane silage with or without Lactobacillus buchneri, and burnt sugar cane silage with or without L. buchneri on ingestive behavior, nitrogen balance and synthesis of microbial nitrogen compounds of dairy cows. Five ¾ Holstein x Gir crossbred cows, assigned to a 5 x 5 Latin square design, were given diets with a 60:40 forage: concentrate ratio on a dry matter basis, to meet an average body weight of 550 kg and production of 15 kg of milk per day. The treatment with fresh sugar cane showed higher values (p 0.05) for dry matter feed efficiency (3,133.3 vs 2,234.47 g DM h-1) and rumination (1,642.3 vs 1,222.93 g DM h-1) compared to the silages. There was a shorter total chewing time (58.7 vs 81.5 min. kg-1 DM) for fresh sugar cane when compared to silages without inoculum. The addition of microbial additive during ensiling of sugar cane did not alter (p > 0.05) the nitrogen intake and balance, but led to a greater (p 0.05) synthesis of microbial nitrogen. Microbial efficiency was not affected (p > 0.05), and showed an average value of 204.32 g microbial crude protein kg-1 total digestible nutrients.(AU)

Objetivou-se avaliar o efeito da utilização de cana-de-açúcar in natura, silagem de cana sem ou com Lactobacillus buchneri e cana queimada sem ou com L. buchneri sobre o comportamento ingestivo, balanço de nitrogênio e síntese de compostos nitrogenados microbianos em vacas lactantes. Foram utilizadas cinco vacas mestiças, ¾ Holandês x Gir, distribuídas em um quadrado latino 5 x 5 e alimentadas com dietas compostas por 60% de volumoso e 40% de concentrado na base da matéria seca, para atender um peso corporal médio de 550 kg e produção média de 15 kg de leite por dia. A cana-de-açúcar in natura proporcionou maiores valores (p 0,05) para eficiência de alimentação da matéria seca (3.133,3 vs 2.234,47 g MS h-1) e de ruminação (1.642,3 vs 1.222,93 g MS h-1) em relação às silagens. Observou-se menor tempo de mastigação total (58,7 vs 81,5 min. kg-1 de MS) para cana-de-açúcar in natura quando comparada às silagens sem inóculo. A utilização do aditivo microbiano na ensilagem da cana-de-açúcar não alterou (p > 0,05) o consumo e o balanço de nitrogênio, porém propiciou maior (p 0,05) síntese de nitrogênio microbiano. Não houve diferença entre as dietas (p > 0,05) para eficiência microbiana, cujo valor médio foi de 204,32 g PB microbiana kg-1 de TDN.(AU)

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Características agronômicas e bromatológicas de seis cultivares de girassol (Helianthus annuus L.), colhidas aos 95 e 110 dias após a semeadura, foram avaliadas para produção de silagem. Utilizaram-se os híbridos Cargill C 11, Braskallb DK 180, Braskallb DK 4040, Morgon M 92007, Morgon M 742 e a variedade V 2000 da EMBRAPA. O delineamento foi o de blocos casualizados, com quatro repetições, em esquema fatorial 2 x 6, sendo considerados como fatores a idade de corte e as cultivares. As plantas foram picadas mecanicamente em partículas de 2,0 a 3,0 cm de tamanho e ensiladas por 30 dias em silos de "PVC" com dez centímetros de diâmetro e quarenta centímetros de comprimento. Avaliaram-se as produções e os teores de matéria seca (MS), concentrações de proteína bruta (PB), extrato etéreo (EE), fibra em detergente neutro (FDN) e os valores de digestibilidade "in vitro" da matéria seca (DIVMS) e de pH das silagens. A maior produção de MS foi de 11,27 t/ha, enquanto a menor foi de 4,88 t/ha, respectivamente, das cultivares M 92007 e V 2000. Em relação a todas as características avaliadas das silagens, observou-se diferença significativa entre as duas idades de corte utilizadas. As cultivares apresentaram comportamento distinto para cada idade de corte analisada. Os resultados permitiram concluir que ocorrem diferenças bromatológicas nas silagens em função das cultivares e da idade de corte utilizada.

Agronomic and chemical characteristics of six cultivars of sunflower (Helianthus annus L.) harvested at 95 and 110 days after sowing, were evaluated for silage production. The hybrids Cargill C 11, Braskallb DK 180, Braskallb DK 4040, Morgon M 92007, Morgon M 742 and the variety V 2000 of EMBRAPA were studied. The experimental design used was a randomized complete block with four replications, in 2 x 6 factorial arrangement, being considered as factors cutting age and cultivars. Plants were mechanically chopped to reach 2.0 to 3.0 cm of particle size and ensiled for 30 days in PVC silos with ten centimeters of diameter and forty centimeters of length. Dry matter (DM) yield and content of moisture, crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), values of "in vitro'' dry matter disappearance (IVDMD) and pH of silages were measured. The highest dry matter production was 11.27 t/ha, and the lowest 4.88 t/ha, respectively, for the cultivars M-92007 and V2000. Based on analyzed characteristics of silages, a significant difference was observed between the two cutting ages tested. Cultivars showed different performance at each cutting age. In general, based on results it may be concluded that chemical differences in silages were related to the sunflower cultivars and cutting ages.