The experiment was conducted to assess the effects of maternal nutrition in late gestation on glycogen pools of newborn piglets of different birth weights and to assess how rapidly the glycogen pools in the liver and 3 muscles are mobilized during fasting. Until d 108 of gestation, 48 sows were fed a gestation standard diet (GSD) with low dietary fiber (DF, 17.1%), or 1 of 3 diets with high DF (32.3 to 40.4%) consisting of pectin residue (GPR), potato pulp (GPP), or sugar-beet pulp (GSP). From d 108 until farrowing, sows were fed 1 of 6 transition diets with low or high dietary fat: one group received a standard diet (TSD; control) containing 3% animal fat, another group received the TSD diet + 2.5 g/d of hydroxy-methyl butyrate as topdressing (THB), and 4 other groups received diets with 8% added fat from coconut oil (TCO), sunflower oil (TSO), fish oil (TFO), or 4% octanoic acid + 4% fish oil (TOA). Two piglets per litter (the second and fifth born) were blood sampled, and 1 was killed immediately after birth, whereas the other, depending on the litter, was killed after 12, 24, or 28.5 to 36 h (mean 32.5 h) of fasting. Samples of liver, LM, M. semimembranousus (SM), and M. diaphragm (DP) were collected and analyzed for glycogen concentration. No dietary effects (P > 0.20) on glycogen concentrations in liver, LM, SM, or DP were observed. The weight of the liver was affected by gestation diet (P < 0.05) and was greater in GSD and GSP piglets (36.7 and 36.3 g) than in GPR piglets (32.6 g), and intermediate (33.6 g) in GPP piglets. Liver weight, estimated muscle mass, and glycogen pools (P < 0.001) were affected by birth weight, whereas glycogen concentrations in liver and LM, SM, and DP muscles were not (P > 0.05). Liver weight; glycogen concentrations in liver, LM, SM, and DP; and glycogen pools in liver and muscles decreased (P < 0.001) with increasing duration of fasting, and at 32.5 h of fasting, glycogen concentration was reduced by 80% in liver, 64% in DP, 46% in SM, and 36% in LM. Based on a broken-line model, labile glycogen in SM, a locomotory muscle, was estimated to be depleted after 16.4 h of fasting. In conclusion, piglet size had a major impact on estimated glycogen pools, whereas sow nutrition in late gestation had a minor impact, if any. Furthermore, varying proportions of pools of glycogen present in liver and selected muscles were mobilized, and data indicate that newborn piglets are fatally depleted of energy after 16 h of fasting.
The objective was to study the effect of type of concentrate with varying starch and fibre content on growth and gastrointestinal development in preweaned dairy calves. Thirty-two newborn Danish Holstein male calves were allocated to four treatment groups in eight blocks of four calves. An experimental low-starch, high-molasses, high-fibre (EXP) concentrate or a traditional high-starch (TRA) concentrate were fed either at a high (HIGH; 2 3 3.2 kg/day) or a low (LOW; 2 3 1.6 kg/day) whole milk allowance in a 2 3 2 factorial design. TRA contained 350 and EXP 107 g starch/kg dry matter (DM), whereas the NDF content was 136 and 296 g/kg DM, respectively. Metabolizable energy (ME) was 11.2 and 12.2 MJ ME/kg DM in EXP and TRA, respectively. All calves had free access to artificially dried grass hay (9.8 MJ ME/kg DM). Four calves were culled during the experiment. The calves were euthanized either at 38 (12 calves) or 56 days (16 calves) of age. Evaluated across both slaughter ages, there was no difference between TRA and EXP in concentrate and hay intake, rumen weight and papillation. EXP resulted in increased villi number in duodenum and jejunum compared with TRA. Concentrate intake and reticulo-rumen weight was higher for LOW compared with HIGH milk allowance, whereas live weight gain was 20% lower. The results show that a low-starch, high-molasses, high-fibre concentrate with 8% lower ME content tended to reduce daily gain compared with a traditional calf starter concentrate, but resulted in similar ruminal development in preweaned calves both on a high and a low milk allowance fed along with grass hay. Furthermore, the results suggest that the experimental concentrate stimulated intestinal villi growth over that of the traditional concentrate.
Five ruminally cannulated lactating Holstein cows, fitted with permanent indwelling catheters in the mesenteric vein, hepatic vein, portal vein, and an artery were used to study intestinal absorption and net recycling of inorganic phosphate (P(i)) to the gastrointestinal tract. Treatments were low P (LP; 2.4 g of P/kg of DM) and high P (HP; 3.4 g of P/kg of DM). The dietary total P (tP) concentrations were obtained by replacing 0.50% calcium carbonate in the LP diet with 0.50% monocalcium phosphate in the HP diet. Diets were fed for 14 d and cows were sampled on d 14 in each period. Cows were fed restrictively, resulting in equal dry matter intakes as well as milk, fat, and protein yields between treatments. Net P(i) recycling (primarily salivary) was estimated as the difference between net portal plasma flux (net absorption of P(i)) and apparently digested tP (feed - fecal tP difference). Phosphorus intake, apparently digested tP, and fecal tP excretion decreased with LP. An effect of decreased tP intake on net portal plasma flux of P(i) could not be detected. However, despite numerically minute net fluxes across the liver, the net splanchnic flux of P(i) was less in LP compared with that in HP. Though arterial plasma P(i) concentration decreased, net P(i) recycling was not decreased when tP intake was decreased, and recycling of P(i) was maintained at the expense of deposition of P(i) in bones. Data are not consistent with salivary P(i) secretion being the primary regulator of P(i) homeostasis at low tP intakes. On the contrary, maintaining salivary P(i) recycling at low tP intakes indicates that rumen function was prioritized at the expense of bone P reserves.
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