Flávio Augusto Portela Santos

Performance of dairy cows fed high levels of acetic acid or ethanol

Ethanol and acetic acid are common end products from silages. The main objective of this study was to determine whether high concentrations of ethanol or acetic acid in total mixed ration would affect performance in dairy cows. Thirty mid-lactation Holstein cows were grouped in 10 blocks and fed one of the following diets for 7 wk: (1) control (33% Bermuda hay + 67% concentrates), (2) ethanol [control diet + 5% ethanol, dry matter (DM) basis], or (3) acetic acid (control diet + 5% acetic acid, DM basis). Ethanol and acetic acid were diluted in water (1:2) and sprayed onto total mixed rations twice daily before feeding. An equal amount of water was mixed with the control ration. To adapt animals to these treatments, cows were fed only half of the treatment dose during the first week of study. Cows fed ethanol yielded more milk (37.9 kg/d) than those fed the control (35.8 kg/d) or acetic acid (35.3 kg/d) diets, mainly due to the higher DM intake (DMI; 23.7, 22.2, and 21.6 kg/d, respectively). The significant diet × week interaction for DMI, mainly during wk 2 and 3 (when acetic acid reached the full dose), was related to the decrease in DMI observed for the acetic acid treatment. There was a diet × week interaction in excretion of milk energy per DMI during wk 2 and 3, due to cows fed acetic acid sustained milk yield despite lower DMI. Energy efficiency was similar across diets. Blood metabolites (glucose, insulin, nonesterified fatty acids, ethanol, and γ-glutamyl transferase activity) and sensory characteristics of milk were not affected by these treatments. Animal performance suggested similar energy value for the diet containing ethanol compared with other diets. Rumen conversion of ethanol to acetate and a concomitant increase in methane production might be a plausible explanation for the deviation of the predicted energy value based on the heat of combustion. Therefore, the loss of volatile compounds during the drying process in the laboratory should be considered when calculating energy content of fermented feedstuffs.

Desempenho de vacas em lactação recebendo dietas com diferentes teores de amido total, acrescidas ou não de levedura (Saccharomyces cerevisiae)

Trinta e seis vacas da raca Holandesa (258 dias em lactacao) foram utilizadas para se avaliar a suplementacao com levedura (Levucell SC 20 da Lallemand) em dietas para vacas leiteiras com dois teores de amido (22 vs 32%). O mais baixo teor de amido foi obtido com a substituicao parcial (50:50) de milho finamente moido por polpa de citrus peletizada. Utilizou-se quadrado latino 4 x 4 repetido, com quatro periodos de 24 dias. Os primeiros 20 dias foram destinados a adaptacao dos animais e os ultimos quatro, a coleta de dados. Os parâmetros avaliados foram a ingestao de materia seca, a producao e composicao do leite e as concentracoes de glicose e nitrogenio ureico no plasma sanguineo. A ingestao de materia seca, a producao e composicao do leite e a concentracao de glicose plasmatica nao foram afetadas pelos tratamentos. O nitrogenio ureico no leite foi maior nos animais sob suplementacao com aditivo microbiologico. O nitrogenio ureico no plasma foi reduzido com a substituicao parcial do milho pela polpa citrica, que nao teve efeito negativo sobre o desempenho de vacas produzindo, em media, 19 kg de leite/dia.

Processamento de milho (floculado vs. laminado a vapor) e adição de monensina para bezerras leiteiras, pré e pós-desmama precoce

The supplementation of more digestible starch sources and feed additives with coccidiostatic and growth promoting activities may improve pre and post weaning calves performance. The objective of this trial was to evaluate the effects of concentrates containing processed grains (steam-flaked vs. steam-rolled), with or without monensin, on intake, weight gain and blood parameters of baby calves, before and after weaning at six weeks of life. Thirty-two female calves were utilized on a completely randomized block, with a 2 x 2 factorial arrangement. The animals received concentrate ad libitum up to 2 kg/d, plus 4 L of milk. Calves had free access to water. After weaning, at the sixth week of life, calves received concentrate and chopped hay. The treatments did not affect concentrate or hay intake, final live weight, average daily gain, plasma glucose and NEFA cocentration. PUN was lower on calves fed steam-rolled corn and monensin. There was a significant effect of age on glucose, PUN, and NEFA concentrations. Only glucose and NEFA were affected by time after feeding. Addition of monensin or processed grain to dairy calves diet did not result on better performance, before or after weaning.

Produção e composição do leite de vacas mantidas em pastagens de capim-elefante submetidas a duas frequências de pastejo

Objetivou-se avaliar duas frequencias de pastejo em pastagens de capim-elefante (Pennisetum purpureum Schum. cv. Cameroon): uma variavel, determinada pela entrada dos animais na area a ser pastejada, quando o dossel atingisse 95% de interceptacao da radiacao fotossinteticamente ativa; e uma frequencia fixa, de 26 dias. Utilizaram-se oito vacas com media de 124 dias em lactacao, 516 kg de peso corporal e 17,5 kg de leite no inicio do experimento. O periodo experimental foi de 80 dias, divididos em quatro subperiodos de 20 dias. O delineamento experimental utilizado foi o cross-over. As frequencias de pastejo nao influenciaram a producao e composicao do leite, o nitrogenio ureico no plasma, o escore de condicao corporal e a variacao de peso corporal. Entretanto, a taxa de lotacao e a producao de leite por unidade de area foram maiores nas pastagens com intervalo de pastejo determinado pela interceptacao de 95% da radiacao fotossinteticamente ativa. Assim, a frequencia de pastejo definida em intervalos variaveis por meio da interceptacao da radiacao fotossinteticamente ativa resulta em maior producao de leite por unidade de area.

Metabolizable protein supply according to the nrc (2001) for dairy cows grazing elephant grass

Tropical pastures fertilized with nitrogen may have high crude protein (CP) contents with high rumen degradability. High crude protein concentrates offered to cows grazing these pastures may increase feed costs without positive effects on their performance. The objectives of this trial were to evaluate the effects of increasing metabolizable protein (MP) supply beyond the NRC (2001) recommendations for mid lactating dairy cows grazing elephant grass pasture (Pennisetum purpureum Schum. cv. Napier) managed with high stocking rates. Three concentrates (6.3 kg DM-1 cow-1 day-1) were evaluated: control (17%CP) was adjusted in relation to MP according to the NRC (2001); the other two contained extra soybean meal, to increase the CP content to 21.2% (CP) and 25.0% (CP). Twelve multiparous Holstein cows, averaging 150 days of milk production at a rate of 19.5 kg of milk day-1, were used in a 3 × 3 latin square design, replicated four times. Forage consumption was 11,270 kg DM ha-1 with 34% of green leaves and 12% CP. Milk production, corrected to 3.5% fat, milk fat, protein, lactose and total solids contents were not affected by treatments (P > 0.05). Milk urea nitrogen and plasma urea nitrogen increased linearly (P 0.05) body weight gain, body condition score, grazing time, ruminating time, resting time, rectal temperature and respiratory rate. Crude protein content in the concentrate formulated according to NRC (2001) is adequate for mid lactating cows grazing tropical pastures.

Parâmetros de fermentação e medidas morfométricas dos compartimentos ruminais de bezerros leiteiros suplementados com milho processado (Floculado vs. Laminado a vapor) e monensina

The objective of this study was the evaluation of the effects of grain processing (steam-rolled vs. steam-flaked) and monensin on ruminal parameters. Sixteen Holstein calves were ruminally canulated with 3 to 5 days of life, and utilized on a completely randomized design block with a 2 x 2 factorial arrangement. The animals received concentrate ad libitum up to 2 kg/d, plus 4 L/d of milk. Calves had free access to water. After weaning at the eight weeks of life, calves received concentrate and chopped hay. Animal performance, concentrate and hay intakes were lower than expected and not affected by treatments. The molar proportion of propionate was higher for steam-rolled concentrate. There was a tendency for higher total VFA (P = .11) and butyrate (P = .13) for steam-rolled corn. Monensin tended to reduce ruminal N-NH3 concentration (P = .12). Weight of reticulum-rumen (as % total tract) tended (P = .09) to be higher for calves on steam-rolled and monensin concentration. However, the capacity of reticulum-rumen was increased by steam-rolled and monensin feeding. Steam-flaked concentrate resulted on heavier abomasum, as % total tract.

Evaluation of external markers to estimate fecal excretion, intake, and digestibility in dairy cows

The objective of this study was to compare the use of an external marker titanium dioxide (TiO2) as an alternative to chromic oxide (Cr2O3) in dairy cows. Four dairy cows were allocated in individual pens and fed concentrate supplement and Pennisetum purpureum cv. Cameroon cut daily. Fecal excretion, forage and total dry matter (DM) intakes, and digestibility were measured and estimated with TiO2 and Cr2O3. Chromic oxide overestimated and TiO2 tended to overestimate fecal excretion compared with total fecal collection. Forage and total DM intakes were overestimated by Cr2O3. The apparent DM digestibility was underestimated by Cr2O3 and TiO2. The organic matter (OM) digestibility was underestimated by both markers. There were greater mean bias, mean squared prediction error, and root of the mean squared prediction errors for all parameters estimated with Cr2O3. In conclusion, estimates using TiO2 were more precise and accurate indicating that it can replace Cr2O3 as an external marker for grazing dairy cows.

Effect of protein supplementation on milk production and metabolism of dairy cows grazing tropical grass

The objectives of this study were to determine if midlactation dairy cows (Bos taurus L.) grazing intensively managed elephantgrass would have their protein requirement met exclusively with the pasture and an energy concentrate, making the use of protein ingredients unnecessary, as well as to determine the dietary crude protein (CP) content that would optimize the efficiency of N utilization (ENU). Thirty-three Holstein and crossbred (Holstein × Jersey) midlactation dairy cows, producing approximately 20 kg/d, were grouped within breed into 11 blocks according to milk yield and days in milk. Within blocks, cows were randomly assigned to 1 of 3 treatments and remained in the study for 11 wk. The control treatment contained only finely ground corn, minerals, and vitamins, and it was formulated to be 8.7% CP. Two higher levels of CP (formulated to be 13.4 and 18.1%) were achieved by replacing corn with solvent-extracted soybean meal (SSBM). Pasture was fertilized with 50 kg of N/ha after each grazing cycle and averaged 18.5% CP (dry matter basis). No differences were observed in milk yield or milk fat, protein, and casein content or casein yield. In addition, pasture intake was not different among treatments. Milk urea N increased linearly as the concentrate CP content increased. Cows fed the 8.7% CP concentrate had higher ENU. In another experiment, 4 ruminally cannulated Holstein dry cows were used in a metabolism trial designed in a 4×4 Latin square. Cows were fed the same treatments described as well as a fourth treatment with 13.4% CP in the concentrate, in which urea replaced SSBM as the main N source. Ruminal volatile fatty acid concentration and microbial synthesis were not affected by levels or sources of N in the concentrate. Ruminal NH(3)N content increased as the concentrate CP content increased. Inclusion of SSBM in the concentrate did not increase production and decreased the ENU of midlactation dairy cows grazing on tropical forage. Supplementation of an 8.7% CP concentrate, resulting in a diet with CP levels between 15.3 and 15.7% of dry matter, was sufficient to meet the protein requirements of such milk production, with the highest ENU (18.4%).

Diet crude protein content and sources for lactating dairy cattle

O fornecimento de dietas com maior teor de proteina para aumentar o fluxo de aminoacidos para o intestino pode aumentar o desempenho lactacional. Compararam-se dietas para vacas em lactacao contendo 16% de proteina bruta (PB), adequada em proteina degradavel no rumen (PDR) e proteina metabolizavel (PM) (NRC, 2001) com dietas com maiores teores de PB (17,5%) . Quarenta e duas vacas (27 primiparas e 15 multiparas, com 172 dias em lactacao) foram utilizadas em um delineamento do tipo Quadrado Latino 3 ´ 3, com 14 repeticoes. A dieta controle continha 16% de PB e era adequada em PDR e PM de acordo com o NRC (2001). O teor de PB das dietas foi aumentado para 17,5% atraves do aumento no fornecimento de farelo de soja e de algodao (SBCS-17,5) para aumentar a PM, ou ureia (U-17,5) para aumentar a PDR. O experimento teve duracao de 60 dias com tres subperiodos. Os animais foram alimentados em grupo com racao completa e ordenhados duas vezes ao dia. O consumo de materia seca foi maior para a dieta U-17,5 (p 0,05) pelos tratamentos. O teor de proteina foi reduzido (p < 0,01) pelo maior fornecimento de ureia (U-17,5); enquanto maior producao de proteina do leite (p < 0,01) foi observada para o tratamento SBCS-17,5. Para vacas produzindo em torno de 29 kg d-1, aumentar o teor de PB para 17,5%, por meio do maior fornecimento de farelo de soja e de algodao, acima das recomendacoes do NRC (2001) para PDR e PM, resultou em aumentos na producao de leite, leite corrigido para gordura e de proteina do leite.

Desempenho e desenvolvimento do trato digestório superior de bezerros leiteiros alimentados com concentrado de diferentes formas físicas

The physical form of concentrate on the performance and rumen development on dairy calves was evaluated in this experiment. Twenty-two Holstein male calves, with 42.3 kg initial body weight, were individually housed, fed 4 L/d of liquid diet and starter concentrate in two physical forms (pelleted or coarsely ground). Starter concentrate intake was monitored daily and calves were weighted weekly, always after the morning liquid diet feeding. After 10 weeks, four calves from each treatment were slaughtered and rumen samples were taken for pH, rumen short chain fatty acids (SCFA) and N-NH3 concentration. Morphometric measurement of the forestomach was also evaluated. There was no effect of the physical form on starter concentrate intake, body weight, and daily gain. The physical form of the concentrate also had no effects on pH, SCFA or N-NH3 rumen concentration, nor on the morphometric measurements of the forestomach, except for rumen capacity and abomasum weight, which were higher for animals fed pelleted starter concentrate. Coarsely ground starter concentrate may be an alternative to reduced production costs since the physical form of the concentrate had no effect on performance or in the development of forestomach of dairy calves.