K. M. Wood

Influence of feeding increasing levels of dry corn distillers grains plus solubles in whole corn grain-based finishing diets on total tract digestion, nutrient balance, and excretion in beef steers.

Four crossbred steers (average BW = 478 ± 33 kg) were used in a 4 × 4 Latin square design to determine the effects of dietary concentration of dry corn distillers grains plus solubles (DDGS) in whole corn-based finishing diets on total tract digestion and nutrient balance and excretion. The DDGS were fed at 0% (control), 16.7%, 33.3%, and 50% of dietary DM. All diets contained 10% (DM basis) alfalfa/grass haylage and were formulated to meet or exceed the estimated requirements for CP. Steers were fed the experimental diets ad libitum for a 14-d adaptation period followed by a 5-d period for fecal and urine collection. Increasing concentration of DDGS in diets from 0 to 50% of DM linearly decreased (P < 0.05) total tract DM and starch digestibility (from 77.8 to 72.9%, and 89.2 to 81.5%, respectively). Daily N and P intakes linearly increased (P = 0.06 and P = 0.01, respectively) with increasing DDGS concentration. Fecal and urinary N, P, S, Mg, and K excretion linearly increased (P < 0.05) with increasing DDGS concentration; however, Se and Na excretion did not differ (P > 0.38) among treatments. Retention (g/d; intake minus urinary and fecal excretion) of N did not differ (P > 0.16) among treatments. Retention of P tended (P = 0.07) to linearly increase and retention of S (g/d) linearly increased (P = 0.004), with increasing DDGS concentration. There were no effects (P > 0.16) of dietary treatment on digestion and retention of Se, Mg, K, and Na. Plasma P and S concentrations increased (P = 0.03 and 0.01, respectively) with increasing DDGS concentration. These data indicate that feeding DDGS up to 50% of dietary DM in whole corn grain-based finishing diets does not have a negative effect on nutrient retention but decreases digestibility. Total excretion of N, P, Ca, Mg, S, and K increased as DDGS concentration increased.

Effect of moderate dietary restriction on visceral organ weight, hepatic oxygen consumption, and metabolic proteins associated with energy balance in mature pregnant beef cows,

Twenty-two nonlactating multiparous pregnant beef cows (639 ± 68 kg) were used to investigate the effect of dietary restriction on the abundance of selected proteins regulating cellular energy metabolism. Cows were fed at either 85% (n = 11; LOW) or 140% (n = 11; HIGH) of total NE requirements. The diet consisted of a haylage-based total mixed ration containing 20% wheat straw. Cows were slaughtered by block (predicted date of parturition), beginning 83 d after the initiation of dietary treatments and every week thereafter for 6 wk, such that each block was slaughtered at approximately 250 d of gestation. Tissue samples from liver, kidney, sternomandibularis muscle, ruminal papilli (ventral sac), pancreas, and small intestinal muscosa were collected at slaughter and snap frozen in liquid N2. Western blots were conducted to quantify abundance of proliferating cell nuclear antigen (PCNA), ATP synthase, ubiquitin, and Na/K+ ATPase for all tissues; PPARγ, PPARγ coactivator 1 α (PGC-1α), and 5´-adenosine monophosphate-activated protein kinase (AMPK) and the activated form phosphorylated-AMPK (pAMPK) for liver, muscle, and rumen; phosphoenolpyruvate carboxykinase (PEPCK) for liver and kidney; and uncoupling protein 2 (UCP2) for liver. Statistical analysis was conducted using Proc Mixed in SAS and included the fixed effects of dietary treatment, cow age, block, and the random effect of pen. Dietary treatments resulted in cows fed HIGH having greater (P ≤ 0.04) ADG and final BW than cows fed LOW. Abundance of ubiquitin in muscle was greater (P = 0.009) in cows fed LOW, and PCG-1 α in liver was greater (P = 0.03) in cows fed HIGH. Hepatic O2 consumption was greater in HIGH (P ≤ 0.04). Feed intake can influence the abundance of important metabolic proteins and suggest that protein degradation may increase in muscle from moderately nutrient restricted cows and that energy metabolism in liver increases in cows fed above NE requirements.

Influence of feeding increasing levels of dry or modified wet corn distillers grains plus solubles in whole corn grain-based finishing cattle diets on pancreatic α-amylase and trypsin activity

Abstract: The objectives of this study were to determine the effect of dietary inclusion [0%-50% of diet dry matter (DM)] and form (dry and modified wet) of corn distillers grains plus solubles (DGS) on pancreatic α-amylase and trypsin activities in calves. Feeding up to 50% DGS did not negatively impact pancreatic exocrine function.

Effect of crop residues in haylage-based rations on the performance of pregnant beef cows

Seventy-one individually fed multiparous, pregnant crossbred beef cows [body weight (BW) ± SD; 730 ± 77.9 kg] were used to examine the effects of including crop residues in alfalfa/grass haylage-based rations on BW gain, fat deposition/loss and plasma metabolites. The haylage control ration (CON; n = 23) was modified to include either 40% (dry matter basis) wheat straw (WS; n = 24) or 40% corn stalklage (CS; n = 24). Cows were blocked by calving date and randomly assigned to each treatment and fed for 82 d leading up to the earliest calving date. On days 1, 40, and 82, cows were weighed, ultrasounded to measure subcutaneous backfat (BF) over the ribs, body condition scored (BCS) and plasma was collected. Calves from cows fed WS had greater (P = 0.02 ) weaning weights than cows fed CS, but did not differ (P = 0.23) from CON. CS cows had the lowest ADG (P < 0.03), lost the most body condition (P < 0.04), and had the lowest dry matter intake (P ≤ 0.001). These data indicate that diets containing crop residue...

Maternal nutrient restriction in mid-to-late gestation influences fetal mRNA expression in muscle tissues in beef cattle

BackgroundManipulating maternal nutrition during specific periods of gestation can result in re-programming of fetal and post-natal development. In this experiment we investigated how a feed restriction of 85% compared with 140% of total metabolizable energy requirements, fed to cows during mid-to-late gestation, influences phenotypic development of fetuses and mRNA expression of growth (Insulin-Like Growth Factor family and Insulin Receptor (INSR)), myogenic (Myogenic Differentiation 1 (MYOD1), Myogenin (MYOG), Myocyte Enhancer Factor 2A (MEF2A), Serum Response Factor (SRF)) and adipogenic (Peroxisome Proliferator Activated Receptor Gamma (PPARG)) genes in fetal longissimus dorsi (LD) and semitendinosus (ST) muscle. DNA methylation of imprinted genes, Insulin Like Growth Factor 2 (IGF2) and Insulin Like Growth Factor 2 Receptor (IGF2R), and micro RNA (miRNA) expression, were also examined as potential consequences of poor maternal nutrition, but also potential regulators of altered gene expression patterns.ResultsWhile the nutrient restriction impacted dam body weight, no differences were observed in phenotypic fetal measurements (weight, crown-rump length, or thorax circumference). Interestingly, LD and ST muscles responded differently to the differential pre-natal nutrient levels. While LD muscle of restricted fetal calves had greater mRNA abundances for Insulin Like Growth Factor 1 and its receptor (IGF1 and IGF1R), IGF2R, INSR, MYOD1, MYOG, and PPARG, no significant differences were observed for gene expression in ST muscle. Similarly, feed restriction had a greater impact on the methylation level of IGF2 Differentially Methylated Region 2 (DMR2) in LD muscle as compared to ST muscle between treatment groups. A negative correlation existed between IGF2 mRNA expression and IGF2 DMR2 methylation level in both LD and ST muscles. Differential expression of miRNAs 1 and 133a were also detected in LD muscle.ConclusionsOur data suggests that a nutrient restriction of 85% as compared to 140% of total metabolizable energy requirements during the 2nd half of gestation can alter the expression of growth, myogenic and adipogenic genes in fetal muscle without apparent differences in fetal phenotype. It also appears that the impact of feed restriction varies between muscles suggesting a priority for nutrient partitioning depending on muscle function and/or fiber composition. Differences in the methylation level in IGF2, a well-known imprinted gene, as well as differences in miRNA expression, may be functional mechanisms that precede the differences in gene expression observed, and could lead to trans-generational epigenetic programming.

The influence of pregnancy and plane of nutrition during pregnancy on pancreatic digestive enzymes and insulin-containing cell cluster morphology in beef cows

Abstract: To determine effects of pregnancy (experiment 1) and plane of nutrition during pregnancy (experiment 2) on pancreatic digestive enzymes and morphology of insulin-containing cell clusters, beef cows were slaughtered, and the pancreas collected 4 wk before parturition (if pregnant or similar time on feed for nonpregnant cows). In experiment 1, mature, nonlactating cows [717 ± 70 kg; nine pregnant (PREG) and nine nonpregnant (OPEN)] were used. In experiment 2, nonlactating, pregnant cows (639 ± 68 kg) were fed at 85% (n = 11; LOW) or 140% (n = 11; HIGH) of net energy (NE) requirements. Concentration (U g-1) and content (U kg-1 BW) of α-amylase and trypsin activities were greater (P ≤ 0.05) in OPEN than PREG cows. Pregnant cows had greater (P ≤ 0.03) insulin-cell cluster size and proportion of large insulin-containing cell clusters than OPEN cows. Concentration and content of α-amylase activity were greater (P ≤ 0.04) in HIGH than LOW cows. These data indicate that pregnancy status (PREG vs. OPEN) impacts pancreatic exocrine and endocrine functions and that plane of nutrition (85% vs. 140% of NE requirements) of pregnant cows may not greatly impact pancreatic exocrine and endocrine functions.

The effect of pregnancy on weight change, visceral organ mass and circulating serum metabolites in mature beef cows

During the last trimester of gestation, fetal growth dramatically increases and results in increased nutrient demand in order to support growth (NRC, 1996). Freetly et al. (2008) suggested that cows may be able to reduce maintenance energy costs in order to support the energetic demands of the conceptus. Although visceral organs account for approximately 10% of bodyweight (BW) they represent about 50% of total energy costs (Reynolds et al., 1991) and can be attributed to maintenance energy costs and energy expenditures (McBride and Kelly, 1990). Little is known about the effect of pregnancy in mature beef cows on visceral organ mass and metabolism. By better understanding the metabolic role of pregnancy, there may be opportunities to better understand maintenance energy costs and improve overall feed efficiency.