Starch levels on performance, milk composition and energy balance of lactating dairy cows.

The objective of this experiment was to evaluate the effects of starch levels in diets with the replacement of citrus pulp for corn on milk yield, milk composition, and energy balance of lactating dairy cows. Twenty-eight multiparous Holstein cows were used in seven 4 × 4 Latin squares conducted concurrently, and each experimental period consisted of 20 days (16 days for adaptation and 4 days for sampling). The experimental treatments comprised four starch levels: 15, 20, 25, and 30% in the diet. The dry matter intake increased linearly with increasing starch levels. The milk yield and 3.5% fat-corrected milk yield showed quadratic response to increasing starch levels. The milk protein content and milk total solids content responded linearly to increasing starch levels. The feed efficiency, milk lactose content, milk urea nitrogen, plasma urea nitrogen, and plasma glucose concentration were not affected by starch levels. The estimated net energy for lactation (NEL) intake increased linearly as the starch level was raised. Although the milk NEL output per kilogram of milk was not affected by starch, the milk NEL output daily responded quadratically to starch levels. In addition, the NEL in body weight gain also responded quadratically to increasing starch levels. The efficiency of energy use for milk yield and the NEL efficiency for production also responded quadratically to increasing starch levels. Diets for mid-lactating dairy cows producing around 30 kg/day of milk should be formulated to provide around 25% starch to optimize performance.

Diet crude protein reduction on follicular fluid and cumulus-oocyte complexes of mid-lactating Girolando cows.

This study evaluated the effect of crude protein (CP) reduction in four diets (156, 139, 132, and 127 g Kg-1 DM) maintaining constant metabolizable protein (188 g/day) on the follicular fluid and cumulus-oocyte complexes of mid-lactating Girolando cows. Twenty-two Girolando cows with average of 21.55 ±3.19 L daily milk yield, 105.30 ±22.62 days in lactation and 3.22 ±0.03 body condition score were selected. To reduce CP in diets and maintain constant metabolizable protein, urea and soybean meal were gradually replaced by lignosulfonate-treated soybean meal (SoyPass®, Cargill), resulting in an increase in rumen-undegradable protein and a reduction in rumen degradable protein. A linear and quadratic reduction was observed in the plasma and follicular fluid urea nitrogen concentration following CP reduction, with the most intense reduction occurring in the 127 g Kg-1 DM group (p<0.001). As CP reduced, there was a tendency for a linear increase in the follicular growth rate (P=0.0696), on the number and proportion of viable oocytes (P<0.09), and also a linear increase for the number (P=0.0397) and proportion (P<0.09) of grade I viable oocytes. Plus, there was a linear effect for the number of cumulus oophorus cells. Cows fed with the lowest amount of CP had cumulus-oocyte complexes with higher numbers of cumulus oophorus cells (P=0.0238). Also, the reduction of diet crude protein was followed by a decrease in the probability of oocytes' DNA degradation. In conclusion, the reduction of CP in the diet of mid-lactating Girolando cows, reduces urea nitrogen concentration in both blood plasma and follicular fluid, and, as a consequence, increases the viability of oocytes and the number of cumulus oophorus cells while reducing oocytes' DNA degradation of follicular included cumulus-oocyte complex. The reduction on dietary CP may improve in vivo oocytes' embryo development impacting fertility of lactating dairy cows.

Diet crude protein reduction on follicular fluid and cumulus-oocyte complexes of mid-lactating Girolando cows

This study evaluated the effect of crude protein (CP) reduction in four diets (156, 139, 132, and 127 g Kg-1 DM) maintaining constant metabolizable protein (188 g/day) on the follicular fluid and cumulus-oocyte complexes of mid-lactating Girolando cows. Twenty-two Girolando cows with average of 21.55 ±3.19 L daily milk yield, 105.30 ±22.62 days in lactation and 3.22 ±0.03 body condition score were selected. To reduce CP in diets and maintain constant metabolizable protein, urea and soybean meal were gradually replaced by lignosulfonate-treated soybean meal (SoyPass®, Cargill), resulting in an increase in rumen-undegradable protein and a reduction in rumen degradable protein. A linear and quadratic reduction was observed in the plasma and follicular fluid urea nitrogen concentration following CP reduction, with the most intense reduction occurring in the 127 g Kg-1 DM group (p<0.001). As CP reduced, there was a tendency for a linear increase in the follicular growth rate (P=0.0696), on the number and proportion of viable oocytes (P<0.09), and also a linear increase for the number (P=0.0397) and proportion (P<0.09) of grade I viable oocytes. Plus, there was a linear effect for the number of cumulus oophorus cells. Cows fed with the lowest amount of CP had cumulus-oocyte complexes with higher numbers of cumulus oophorus cells (P=0.0238). Also, the reduction of diet crude protein was followed by a decrease in the probability of oocytes' DNA degradation. In conclusion, the reduction of CP in the diet of mid-lactating Girolando cows, reduces urea nitrogen concentration in both blood plasma and follicular fluid, and, as a consequence, increases the viability of oocytes and the number of cumulus oophorus cells while reducing oocytes' DNA degradation of follicular included cumulus-oocyte complex. The reduction on dietary CP may improve in vivo oocytes' embryo development impacting fertility of lactating dairy cows.(AU)

Substituição do milho em grãos por subprodutos da agroindústria na ração de vacas leiteiras em confinamento / Substitution of Byproducts for Corn Grain in Confined Lactating Cows Diets

Com o intuito de avaliar a substituição do milho em grãos por alimentos alternativos em rações de vacas em lactação, foram conduzidos três experimentos iguais, em que a única diferença foi o alimento testado: No experimento 1 avaliou-se a inclusão do farelo de glúten de milho 21 (FGM-21) em três níveis (0, 10 e 20% da MS) em substituição ao milho moído das rações. A ingestão diária de MS (21,19 kg/an), a produção de leite (24,88 kg/an), a produção de leite corrigido para 3,5% de gordura (25,34 kg/an), o teor de gordura (3,62%), e o teor de sólidos totais (11,86%) não foram afetados pelos tratamentos (P>0,05). A inclusão do FGM-21 afetou os teores de proteína e lactose do leite e a concentração de nitrogênio uréico do leite (P>0,05). No experimento 2 avaliou-se a inclusão da casca de soja (CS) em três níveis (0, 10 e 20% da MS) em substituição ao milho moído das rações. A inclusão da CS não afetou o consumo de matéria seca (22,84 kg/d), nem a produção de leite (28,33 kg/d) e produção de leite corrigido para gordura (28,48 kd/d) (P>0,05). No entanto a inclusão do subproduto aumentou linearmente a produção total de gordura (P<0,05) e a concentração de nitrogênio uréico (P<0,01) no leite. No experimento 3 avaliou-se a inclusão do farelo de trigo (FT) em três níveis (0, 10 e 20% da MS) em substituição ao milho moído das rações. A inclusão do FT reduziu (P<0,05) o consumo de matéria seca (média de 22,20 kg/d) e a produção de leite (P<0,01) (média de 31,65 kg/d), a produção de leite corrigido para 3,5% de gordura (média de 27,44 kg/d), a produção de proteína, gordura e lactose do leite (P<0,05), e consequentemente, a produção de sólidos totais do leite (P<0,05). No entanto os teores dos componentes do leite não foram afetados pelos tratamentos. A inclusão do subproduto causou aumento no teor de nitrogênio uréico no leite (P<0,01)

Four identical experiments were conducted to evaluate the substitution of some byproducts for corn grain in confined lactating cows diets. The only source of variation among them was the byproduct tested. In trial 1 the inclusion of three doses of corn gluten feed (FGM-21) (0, 10 and 20% DM) in substitution for ground corn was evaluated. Treatments did not affect (P>0.10) daily dry matter intake (DMI) (21.19 kg/cow), milk yield (24.88 kg/cow), 3,5% fat corrected milk yield (FCM) (25.34 kg/cow), milk fat content (3.62%), and milk total solids (11.86%). Inclusion of corn gluten feed affected milk protein, lactose and urea concentrations (P<0.05). In trial 2 the inclusion of three doses of soy hulls (0, 10 and 20% DM) in substitution for ground corn was evaluated. Inclusion of soy hulls had no effect on daily dry matter intake (DMI) (22.84 kg/d), milk yield (28.33 kg/d) or fat corrected milk (FCM) yield (28.48 kd/d) (P>0.05). However, inclusion of CS linearly increased total milk fat yield (P<0,05) and linearly decreased MUN (P<0,01). In trial 3 the inclusion of three doses of wheat middlings (FT) (0, 10 and 20% DM) in substitution for ground corn was evaluated. Inclusion of FT reduced (P<0,05) dry matter intake (22.20 kg/d average) and milk yield (P<0,01) (31.65 kg/d average), FCM yield (27.44 kg/d average), total milk fat, protein and lactose, and milk total solids (P<0,05). Milk components concentration was not affected by treatments. Inclusion of the byproduct increased MUN concentration (P<0,01)