Forty cows and twenty heifers were used to study the effects of dietary energy density during late gestation and early lactation on lactation performance and ruminal parameters. A 2 x 2 factorial arrangement of treatments was used. During prepartum (-28 d to calving), animals were fed a low energy density diet [DL; 1.58 Mcal of net energy for lactation (NE(L))/kg, 40% neutral detergent fiber (NDF) and 38% nonfiber carbohydrate (NFC)] or a high energy diet (DH; 1.70 Mcal NE(L)/kg, 32% NDF and 44% NFC). After calving, half of the cows from each prepartum treatment group were assigned to a low energy density diet (L; 1.57 Mcal NE(L)/kg, 30% NDF and 41% NFC) or a high energy density diet (H; 1.63 Mcal NE(L)/kg, 25% NDF and 47% NFC) until d 20 postpartum. After d 20, all cows were fed H until d 70. Animals fed DH had 19.8% greater dry matter intake (DMI; % of body weight) and 21.5% greater energy intake than animals fed DL prepartum and the response was greater for cows compared to heifers. Animals fed DH had lower ruminal pH compared to animals fed DL, but no major changes in volatile fatty acid concentrations were observed. Effects of dietary energy density during prepartum on postpartum production responses were dependent on parity. Primiparous cows fed DL had higher 3.5% fat-corrected milk yield and milk fat production and percentage during the first 10 wk of lactation than those fed DH. Prepartum diet did not affect lactation performance of multiparous cows. Cows fed H had higher DMI and energy intake for the first 20 d of lactation compared to cows fed L. Diets did not affect DMI after the third wk of lactation. Milk production increased faster for cows fed H compared to cows fed L. Animals fed DL-L sequence of treatments tended to have the lowest energy intake during the first 10 wk of lactation. Prepartum treatments did not affect ruminal fermentation characteristics postpartum. Cows fed H had lower ruminal pH and higher propionate concentrations than cows fed L. No prepartum x postpartum interactions were observed for ruminal fermentation parameters. The effects of DH on prepartum DMI did not carry over to the postpartum period or influence early postpartum production. Increasing concentrate content of the diet immediately postpartum instead of delaying the increase until d 21 postpartum is associated with a higher rate of increase.in milk production and higher DMI.

Effects of dietary energy density during late gestation and early lactation on metabolic status of periparturient cows were studied. Four weeks before expected calving, animals were fed a low (DL; 1.58 Mcal of NEL/kg) or high energy density diet (DH; 1.70 Mcal of NEL/kg). After calving, half of the cows from each prepartum treatment were assigned to a low (L; 1.57 Mcal of NEL/kg) or high energy density diet (H; 1.63 Mcal of NEL/kg) until d 20 postpartum. After d 20, all animals were fed H until d 70. Animals fed DH had a more positive energy balance during the prepartum period. Animals fed DH had higher plasma concentrations of glucose and insulin and lower concentrations of plasma nonesterified fatty acid (NEFA) on d -7 relative to calving compared with animals fed DL. No differences in blood concentrations of metabolites, insulin and liver triglycerides (TG) content were observed on d 1. Liver TG content at d 1 and 21 were more related to magnitude of change in energy intake prepartum than to energy intake in the last week of gestation. Cows fed H had higher concentrations of plasma glucose and insulin, but similar plasma NEFA during the postpartum period compared with cows fed L. Plasma concentrations of beta-hydroxybutyrate (BHBA) and liver TG content on d 21 were 46 and 30% lower, respectively, for cows fed H compared with cows fed L. Interactions between prepartum and postpartum treatments indicated that negative effects of delaying higher concentrate feeding until d 21 postpartum can be partially offset by increasing concentrate in the diet before calving. Cows fed L had a higher increase in white line hemorrhage scores between prepartum and 10 wk postpartum compared with cows fed H. Energy density of prepartum diets had a minor influence on metabolic status of cows postpartum. A more favorable metabolic profile occurs when increasing the concentrate content of the diet immediately postpartum compared with delaying the increase until d 21 postpartum.

The objective of this trial was to compare the effects of increasing dietary energy density from 1.51 to 1.65 Mcal/kg of dry matter (DM) by replacing forage with concentrate or by further increasing concentrate via the substitution of corn silage and alfalfa silage by a mixture of straw, starch, and soybean meal. Our hypothesis was that the latter diet would be more glucogenic while increasing rumen fill and be potentially desirable for transition cows. Nine far-off dry cows (greater than 3 wk before parturition at the end of the trial) were fed three diets: low energy diet, [LE, 1.51 Mcal/kg of DM, 14.0% crude protein (CP) and 35% nonfiber carbohydrates (NFC)], high energy diet, (HE, 1.65 Mcal/kg of DM, 13.9% CP and 39.5% NFC) and high energy diet, where a portion of alfalfa and corn silage was replaced by straw, soybean meal, and cornstarch (HES, 1.65 Mcal/kg of DM, 13.5% CP and 40.5% NFC). The experiment was a replicated 3 x 3 Latin square design with 21-d periods. Six cows from two squares were used to examine kinetics of DM disappearance from nylon bags suspended in the rumen. Two contrasts of interest were: LE versus HE, HES (effects of energy density) and HE versus HES (method of increasing energy density). Increasing energy density increased the potentially degradable (B) and decreased the undergradable (C) DM fractions of the diets. Because HES had greater B and a faster rate of degradation of fraction B (k), effective rumen degradable DM (ERDDM) was higher in HES compared to HE. Cows fed high energy diets had greater DM intake. No differences in DM intake were observed between HE and HES. Rumen volume or DM pool sizes were not affected by treatment. High energy diets increased total ruminal fluid volatile fatty acid concentration compared with LE. Propionate concentration was higher in cows fed high energy diets compared with cows fed LE. The partial replacement of alfalfa and corn silage by straw, soybean meal, and cornstarch further increased propionate concentration. The greatest increase in serum insulin concentration following feeding was observed in cows fed HE. Cows consuming high energy diets had lower plasma nonesterified fatty acids (NEFA) before and after feeding. The HES diet was less effective in decreasing plasma NEFA concentration after feeding compared to HE. In conclusion, increasing diet energy density of far-off dry cows positively affected DMI, ruminal propionate, serum insulin, and plasma NEFA. Increasing energy density with a blend of feeds that represent extremes in rates of carbohydrate fermentation may be a strategy to provide greater amounts of glucogenic precursors. Applicability of this strategy should be examined in transition cows.

-Forty Holstein cows, with previous reproductive problems, empty, at second or more lactations, with an average milk production of 9,200 kg in the previous lactation and a dry period over than 50 days were distruibuted in two groups to evaluate two protocols of milking induction. It was given to group 1, on days one, eight and 21 recombinant bovine somatotropin-bSTr (500 mg); from day two to eight, estradiol cypionate (0.075 mg/kg BW) and medroxi progesterone acetate (0.25 mg/kg BW); from days nine to 15, estradiol cypionate (0.037 mg/kg BW); on day 19, prostaglandin F2α (0.530 mg) and from days 19 to 21, isoflupredone acetate (0.05 mg/kg BW). Group two was given, on days one, eight and 21, bSTr (500 mg), from days 2 to 15, estradiol benzoate (0.071 mg/kg BW), from days two to eight, acetate of medroxi progesterone (0.25 mg/kg BW), day 19, prostaglandin F2α(0.530 mg) and from days 19 to 21 isoflupredone acetate, (0.05 mg/kg BW). Teats and udders of all cows were massaged for five minutes from day 17 to 21.Milking were carried out from the 22 nd day of induction. After beginning of lactation, both groups were given bsTr (500 mg) every 14 days. It was used a complete random design with 20 replicates per treatment and a split-plot scheme.Evaluation of the protocols was carried out by using analyses of variance using Fisher´s test at 5% and production of milking per day using regression analyses. Milking was successfully induced in 85% of the animals. Animals from group 2 showed production mean 21.9 ± 12.9 kg of milk/day which was higher than group 1 mean 18.9 ± 11.5 kg of milk/day. There was no difference for milk composition in either groups. Twenty-nine cows were inseminated and 41.1% became pregnant.Key Words: estradiol benzoate, estradiol cypionate, milk production, somatotropin Indução artificial de lactação em bovinosRESUMO -Quarenta vacas holandesas, com problemas reprodutivos prévios, vazias, de segunda ou mais lactações, com produção média de 9.200 kg na lactação anterior, e período seco superior a 50 dias foram distribuídas em dois grupos para avaliar dois protocolos de indução da lactação. O grupo 1 recebeu nos dias um, oito e 21 somatotropina bovina recombinante -bSTr (500 mg); nos dias dois a oito cipionato de estradiol (0,075 mg/kg PV) e acetato de medroxi progesterona (0,25 mg/kg PV), do dia nove ao 15 cipionato de estradiol (0,037 mg/kg PV); no dia 19 prostaglandina F2α (0,530 mg) e dias 19 a 21 acetato de isoflupredona (0,05 mg/kg PV). O grupo 2 recebeu, nos dias um, oito e 21 bSTr (500 mg), nos dias dois a 15 benzoato de estradiol (0,071 mg/kg PV), do dia dois ao oito acetato de medroxi progesterona (0,25 mg/kg PV), no dia 19 prostaglandina F2α (0,530 mg), e dias 19 a 21 acetato de isoflupredona (0,05 mg/kg PV). Todos os animais tiveram o úbere e tetos massageados do dia 17 a 21 por cinco minutos. As ordenhas foram realizadas a partir do 22 o dia da indução. Após o início da lactação, os dois grupos receberam bSTr (500 mg) a cada 14 dias. Utilizou-se delineamento inteiramente ao acaso, co...

Quarenta e oito bezerras da raça Holandesa, de um a 60 dias de idade, foram utilizadas para avaliar os efeitos da adição ou não de Lactobacillus acidophillus, Bifidobacterium bifidum e Enterococus faecium ao leite sem resíduo de antimicrobiano (L) e ao leite de vacas em tratamento de mastite (LTM), sobre o consumo de alimentos, ganho de peso e incidência e duração de diarréia. O consumo de concentrado e água foi medido diariamente, e o ganho de peso semanalmente. Utilizou-se um delineamento inteiramente ao acaso, em esquema de parcelas subdivididas, com 12 repetições. Os tratamentos consistiram de um arranjo fatorial 2 x 2 (L ou LTM e ausência ou presença de probiótico). A adição de probiótico reduziu o número de dias com diarréia no grupo de animais que recebeu leite sem resíduo de antimicrobiano (P<0,05), mas não houve efeito sobre os animais que receberam leite de vacas em tratamento de mastite. Também não houve efeito do probiótico sobre os consumos de concentrado e de água, e sobre o ganho de peso e a incidência de diarréia.