Estimation of metabolisable energy and net energy of rice straw and wheat straw for beef cattle by indirect calorimetry.

Two experiments were conducted to estimate the metabolisable energy (ME) and net energy (NE) of rice straw and wheat straw for beef cattle. In each experiment, 16 Wandong bulls (Chinese indigenous yellow cattle) were assigned to 4 dietary treatments in a completely randomised design. Four dietary treatments included one corn silage-concentrate basal diet and three test diets in which the basal diet was partly substituted by rice straw (Exp. 1) or wheat straw (Exp. 2) at 100, 300 and 600 g/kg. Total collection of faeces and urine was conducted for 5 consecutive days after a 2-week adaption period, followed by a 4-d period where gas exchange measurements were measured by an open-circuit respiratory cage. Linear regression equations of rice straw- or wheat straw-associated ME and NE contribution in test diets against rice straw or wheat straw substitution amount were developed to predict the ME and NE values of rice straw and wheat straw. These regression equations resulted in ME and NE values (dry matter basis) of 6.76 and 3.42 MJ/kg for rice straw and 6.43 and 3.28 MJ/kg for wheat straw, respectively. The NE and ME requirement for maintenance of Wandong cattle fed a straw-based diet were 357 and 562 kJ·kg-0.75·d-1, respectively. The regression-derived ME and NE have lower standard errors and coefficients of variation than those estimated by any single substitution ratio. Our study found that the regression method based on multiple point substitution is more reliable than the substitution method for energy evaluation of feedstuffs for beef cattle.

The Effects of Maternal Obesity on Porcine Placental Efficiency and Proteome.

Maternal obesity is associated with impaired maternal metabolism and affects the developmental programming of the fetus. The placenta is dysfunctional when exposed to an obese intrauterine environment and can transduce and mediate detrimental maternal impacts to the fetus through mechanisms that remain largely unknown. The main objective of this study was to investigate the effects of maternal obesity on the porcine placental proteome and to analyze the deregulated proteins and potential pathways predicted to be disturbed in obese placentas, using sows with high backfat as a model of obese pregnancy. The sows were divided into two groups based on their backfat thickness: normal backfat (NBF, 17-22 mm; n = 30) and high backfat (HBF, ≥23 mm; n = 30) as the maternal obesity group. The placental tissues used for the proteomic and biochemical analyses were obtained through vaginal delivery, and the maternal blood samples used to determine the metabolic parameters were collected at day 107 of pregnancy. Our study demonstrated that HBF sows had significantly decreased placental efficiency, increased plasma-free fatty acids and triglyceride levels, and increased proinflammatory cytokines plasma levels (p < 0.05). HBF placentas had significantly higher malondialdehyde level, lower total antioxidant capacity and antioxidase activity, increased triglyceride content and enhanced proinflammatory tumor necrosis factor- α (TNF-α) and interleukin-6 (IL-6) contents (p < 0.05). Among the 4652 proteins identified using the proteomic method, 343 were quantified as differentially abundant proteins, which were involved in many vital biological processes. Based on our bioinformatic and placental biochemical analyses, we concluded that maternal obesity is associated with abnormal carbohydrate and lipid metabolism, mitochondrial dysfunction, decreased steroid hormone biosynthesis, and increased oxidative stress and inflammation in the placenta. The results of this study are undoubtedly valuable to other researchers.