We hypothesized that gestational nutrition would affect calf feed efficiency and small intestinal biology, which would be correlated with feed efficiency. Multiparous beef cows (n = 36) were individually fed 1 of 3 diets from d 45 to 185 of gestation: native grass hay and supplement to meet NRC recommendations (control [CON]), 70% of CON NEm (nutrient restricted [NR]), or a NR diet with a RUP supplement (NR+RUP) to provide similar essential AA as CON. After d 185 of gestation, cows were managed as a single group, and calf individual feed intake was measured with the GrowSafe System during finishing. At slaughter, the small intestine was dissected and sampled. Data were analyzed with calf sex as a block. There was no effect (P ≥ 0.33) of maternal treatment on residual feed intake, G:F, DMI, ADG, or final BW. Small intestinal mass did not differ (P ≥ 0.38) among treatments, although calf small intestinal length tended (P = 0.07) to be greater for NR than NR+RUP. There were no differences (P ≥ 0.20) in calf small intestinal density or jejunal cellularity, proliferation, or vascularity among treatments. Jejunal soluble guanylate cyclase mRNA was greater (P < 0.03) for NR+RUP than CON and NR. Residual feed intake was positively correlated (P ≤ 0.09) with small intestinal mass and relative mass and jejunal RNA content but was negatively correlated (P ≤ 0.09) with jejunal mucosal density and DNA concentration. Gain:feed was positively correlated (P ≤ 0.09) with jejunal mucosal density, DNA, protein, and total cells and was negatively correlated (P ≤ 0.05) with small intestinal relative mass, jejunal RNA, and RNA:DNA. Dry matter intake was positively correlated (P ≤ 0.09) with small intestinal mass, relative mass, length, and density as well as jejunal DNA and protein content, total cells, total vascularity, and kinase insert domain receptor and endothelial nitric oxide synthase 3 mRNA and was negatively correlated (P = 0.02) with relative small intestinal length. In this study, calf performance and efficiency during finishing as well as most measures of small intestinal growth were not affected by maternal nutrient restriction during early and midgestation. Results indicate that offspring small intestinal gene expression may be affected by gestational nutrition even when apparent tissue growth is unchanged. Furthermore, small intestinal size and growth may explain some variation in efficiency of nutrient utilization in feedlot cattle.

The study evaluated the effects of calf management system after earlyweaning (EW) on performance and liver gene expression of beef heifers. On d 0, Brahman × British heifers (n = 40; BW = 83 ± 10 kg; age = 69 ± 9 d) were stratified by age and BW, and randomly assigned to a control treatment that was normally weaned (NW) on d 177, or 1 of 3 EW treatments, (1) EW and grazed on ryegrass pastures for 67 d then on bahiagrass pastures until NW (Ryegrass), (2) EW and fed a highconcentrate diet in drylot until NW (Drylot), or (3) EW and metabolically imprinted by feeding a high-concentrate diet for 94 d then grazed on bahiagrass pastures until NW (MI). Heifers were assigned to 1 of 2 pens per treatment. On d 177, heifers were grouped by treatment and grazed on bahiagrass pastures until the start of breeding season (d 335). Heifers on pastures were supplemented at 1.0% BW until NW and 1.5% BW from NW to d 335. On d 177 and 335, Ryegrass heifers were lightest (P < 0.01) and Drytlot heifers heaviest (P < 0.001) compared with all other treatments and Control and MI heifer BW did not differ (P ≥ 0.64; BW = 212 and 300, 178 and 264, 216 and 302, and 261 and 333 for Control, Ryegrass, MI, and Drylot on d 177 and 335, respectively; SEM = 7.8). On d 94, liver GHR-1A mRNA was greatest (P < 0.01) for Control, but similar (P = 0.64) among the other treatments, whereas liver IGF-1 mRNA was least (P = 0.004) for Ryegrass, but similar (P > 0.90) among the other treatments. On d 177, liver GHR-1A was greater for Control and Drylot (P < 0.03) than Ryegrass and MI, whereas liver IGF-1 mRNA was greatest for Drylot than all other treatments and greater (P < 0.07) for Control than Ryegrass and MI. On d 260, liver GHR-1A mRNA was least (P < 0.08) for Ryegrass, whereas liver IGF-1 was greater (P < 0.04) for Drylot compared with Ryegrass. Thus, heifer management systems following EW result in significant differences on BW at NW and at the start of breeding season. These impacts appear to affect liver gene mRNA expression, which may persist despite placing heifers on a same plane of nutrition.

Chapter 13 Epigenetics and Effects on the Neonate That May Impact Feed Efficiency Allison M. Meyer, Allison M. Meyer University of Wyoming, USASearch for more papers by this authorJoel S. Caton, Joel S. Caton North Dakota State University, USASearch for more papers by this authorBret W. Hess, Bret W. Hess University of Wyoming, USASearch for more papers by this authorStephen P. Ford, Stephen P. Ford University of Wyoming, USASearch for more papers by this authorLawrence P. Reynolds, Lawrence P. Reynolds North Dakota State University, USASearch for more papers by this author Allison M. Meyer, Allison M. Meyer University of Wyoming, USASearch for more papers by this authorJoel S. Caton, Joel S. Caton North Dakota State University, USASearch for more papers by this authorBret W. Hess, Bret W. Hess University of Wyoming, USASearch for more papers by this authorStephen P. Ford, Stephen P. Ford University of Wyoming, USASearch for more papers by this authorLawrence P. Reynolds, Lawrence P. Reynolds North Dakota State University, USASearch for more papers by this author Book Editor(s):Rodney A. Hill, Rodney A. Hill University of Idaho, USASearch for more papers by this author First published: 10 July 2012 https://doi.org/10.1002/9781118392331.ch13Citations: 6 AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary This chapter contains sections titled: Introduction Developmental Programming Epigenetics Programming of Feed Efficiency Conclusions References Citing Literature Feed Efficiency in the Beef Industry RelatedInformation

Two experiments were conducted to evaluate the effects of rumen-protected fat (RPF) supplementation after or during estrus synchronization on plasma fatty acid concentrations and reproductive performance of lactating beef cows. In Exp. 1, primiparous (n = 59; 495 ± 50 kg) and multiparous cows (n = 43; 552 ± 64 kg) were used in a randomized complete block design. On d -10, cows were stratified by BW and age to receive either a beet-pulp-based supplement fed at 1.8 kg/d per cow (control) or a beet-pulp-based supplement containing RPF at 1.4 kg/d per cow. Cows were estrus synchronized from d –10 to -3, with timed AI on d 0. On d 0, cows were transferred to bromegrass pastures and supplemented for 30 d. In Exp. 2, multiparous cows (n = 168; 525 ± 62 kg) were used in a randomized complete design and estrus synchronized similarly as in Exp. 1. However, cows were supplemented from d –10 to 10 after timed AI. In Exp. 1, plasma concentrations of 18:2n-6 tended to be greater (P = 0.07) for cows fed RPF than for control cows after 30 d. In Exp. 2, plasma concentrations of 18:2n-6 and total fatty acids were greater (P ≤ 0.002) for cows fed RPF after 20 d of supplementation. In Exp. 1 and 2, reproductive performance was similar (P ≥ 0.72) between treatments. Rumen-protected fat fed to lactating beef cows during and after estrus synchronization increased plasma fatty acid status; however, the increased fatty acid status was not sufficient to improve reproductive performance of lactating beef cows.

ABSTRACTChanges in commodity pricing and environmental concerns are changing animal agriculture throughout the United States. Adopting multispecies grazing as an alternative production system could result in improved forage utilization, increased animal performance, and reduced production costs, and thereby improve the financial stability of livestock operations. This study focused on the Silver Spur Ranch near Saratoga, Wyoming, a historical cattle ranch where sheep grazing is being integrated into irrigated and rangeland pastures. The overall objectives of this study were to evaluate the effect of multispecies grazing on changes in botanical composition and nutrient availability following grazing in subirrigated pasture. Forage DM followed the general dietary patterns of animals that were last stocked in the pasture. There were fewer forbs in the north pasture, where sheep grazing followed cattle grazing, and fewer graminoids in the south pasture, where cattle grazing followed sheep grazing. Relative depletion of CP and digestible DM was highest for forbs grazed by sheep after cattle. At the end of the first grazing period, the small north pasture (cattle grazing) had 9.7 d of grazing remaining at the current stocking rate. However, at the end of the second grazing period (sheep following cattle), the small north pasture had 14.7 d of grazing remaining. This represents a 52% increase in days of grazing remaining over the first period. The small south pasture (sheep followed by cattle) had little change from the first grazing period to the second (13.4 vs. 13.0 d).

Background: Both maternal obesity and inflammatory bowel diseases (IBDs) are increasing. It was hypothesized that maternal obesity induces an inflammatory response in the fetal large intestine, predisposing offspring to IBDs.Methods: Nonpregnant ewes were assigned to a control (Con, 100% of National Research Council [NRC] recommendations) or obesogenic (OB, 150% of NRC) diet from 60 days before conception. The large intestine was sampled from fetuses at 135 clays (term 150 clays) after conception and from offspring lambs at 22.5 +/- 0.5 months of age.Results: Maternal obesity enhanced mRNA expression tumor necrosis factor (TNF)alpha, interleukin (IL)1 alpha, IL1 beta, IL6, IL8, and monocyte/macrophage chemotactic protein-1 (MCP1), as well as macrophage markers, CD11b, CD14, and CD68 in fetal gut. mRNA expression of Toll-like receptor (TLR) 2 and TLR4 was increased in OB versus Con fetuses; correspondingly, inflammatory NF-kappa B and JNK signaling pathways were also upregulated. Both mRNA expression and protein content of transforming growth factor (TGF) beta was increased. The IL-17A mRNA expression and protein content was higher in OB compared to Con samples, which was associated with fibrosis in the large intestine of OB fetuses. Similar inflammatory responses and enhanced fibrosis were detected in OB compared to Con offspring.Conclusions: Maternal obesity induced inflammation and enhanced expression of proinflammatory cytokines in fetal and offspring large intestine, which correlated with increased TGF beta and IL 17 expression. These data show that maternal obesity may predispose offspring gut to IBDs.

Angus × Gelbvieh cows with 2 to 3 previous pregnancies were used to evaluate effects of maternal nutrient restriction on offspring adipose tissue morphology at standard production endpoints. At 45 d after AI to a single sire, pregnancy was confirmed and cows randomly allotted into groups and fed a control (Con, 100% of NRC recommendations), nutrient-restricted (NR, 70% of Con diet), or nutrient-restricted + protein-supplemented (NRP, 70% of Con + essential AA supply to the small intestine equal to Con) diet. At d 185 of gestation, cows were commingled and received the Con diet thereafter. Bull calves were castrated at 2 mo of age. Calves were weaned at 210 d, backgrounded for 28 d, and then placed in the feedlot for 195 d. Steers and heifers were slaughtered at an average 12th-rib fat thickness of 7.6 mm. Adipose tissue from selected depots was collected for adipocyte size analysis. There was no significant difference in BW or BCS between Con, NRP, and NR cows at d 45 of gestation, which averaged 489.7 ± 17.7 kg and 5.35 ± 0.13, respectively. At d 185 of gestation, Con and NRP groups had similar BW (566.1 ± 14.8 and 550.2 ± 14.8 kg) and BCS (6.34 ± 0.27 and 5.59 ± 0.27), but NR cows exhibited reduced (P < 0.05) BW (517.9 ± 14.8 kg) and BCS (4.81 ± 0.27). Among offspring (steers and heifers) at slaughter, there were no significant differences in BW or organ weights among treatment groups. Yield grade was reduced (P < 0.05) and semitendinosus weight/HCW tended (P = 0.09) to be reduced in NR offspring compared with Con and NRP offspring. Average adipocyte diameter was increased (P < 0.05) in subcutaneous, mesenteric, and omental adipose tissue and tended (P = 0.09) to increase in perirenal adipose tissue in NR compared with Con offspring with NRP offspring adipocyte diameter being either intermediate or similar to Con calves. The adipocyte size alterations observed in NR offspring were confirmed by DNA concentration of the adipose tissue depots. There also was an increased mRNA expression (P < 0.05) of fatty acid transporter 1 in subcutaneous adipose tissue from NR offspring compared with Con and NRP offspring. Nutritional restriction during early and mid gestation increased or tended to increase (P < 0.09) adipocyte diameter in all adipose tissue depots in finished steer and heifer calves.

Two experiments were conducted to compare ruminal, physiological, and performance responses of forage-fed cattle consuming grain-based supplements without (NF) or with the inclusion (10%; DM basis) of a rumen-protected PUFA (PF) or SFA source (SF). Supplements were offered and consumed at 0.6% of BW/animal daily (DM basis). In Exp. 1, DMI and ruminal in situ forage degradability were evaluated in 3 Angus × Hereford cows fitted with ruminal cannulas and allocated to a 3 × 3 Latin square design. Within each experimental period, hay was offered in amounts to ensure ad libitum access from d 1 to 13, DMI was recorded from d 8 to 13, and cows were limited to receive 90% of their average hay DMI (d 1 to 13) from d 14 to 21. On d 16, polyester bags containing 4 g of ground hay (DM basis) were incubated within the rumen of each cow for 0, 4, 8, 12, 24, 36, 48, 72, and 96 h. Hay and total DMI were reduced (P < 0.05) in cows receiving PF compared with cows receiving SF and NF. No treatment effects were detected (P > 0.48) for ruminal disappearance rate and effective ruminal degradability of hay DM and NDF. In Exp. 2, preconditioning DMI, ADG, carcass traits, and plasma concentrations of cortisol, fatty acids, acute-phase proteins, and proinflammatory cytokines were assessed in 72 Angus × Hereford steers receiving supplement treatments during a 28-d preconditioning period. All steers were transported to a commercial growing lot after preconditioning (d 1) and were later moved to an adjacent commercial finishing yard (d 144), where they remained until slaughter. No treatment effects were detected (P ≥ 0.52) for preconditioning ADG and G:F, but DMI tended (P = 0.09) to be reduced in steers receiving PF compared with those receiving NF and SF. Plasma PUFA concentrations were greater in steers receiving PF compared with those receiving NF and SF (P = 0.01). After transportation, concentration of tumor necrosis factor-α increased for steers receiving NF, did not change for steers receiving SF, but decreased for steers receiving PF (treatment × day interaction, P < 0.01). Steers fed PF had greater (P = 0.02) ADG compared with those fed NF during the growing phase. Carcass yield grade and marbling were greater (P < 0.05) for steers fed PF compared with those fed NF. In conclusion, PUFA supplementation did not affect ruminal forage degradability but did impair DMI in beef cows. Further, PUFA supplementation to steers during preconditioning reduced plasma concentrations of tumor necrosis factor-α after transportation, and benefited growing lot ADG and carcass marbling.

Multiparous ewes received 100% (control, C, n = 13) or 50% (nutrient restricted, NR, n = 14) of NRC dietary requirements from d28-d78 of gestation. On d78, 5 C and 6 NR ewes were necropsied. The remaining 8 C and 8 NR ewes were fed to 100% of NRC from d78-d135 and necropsied. Maternal blood was collected at both necropsies and at weekly intervals for assay of glucose, insulin and leptin. Fetal blood was collected at d78 and d135 necropsies for assay of glucose and lipids. Cotyledonary (COT) tissue was evaluated for protein and mRNA expression [fatty acid transporter (FATP)1, FATP4, CD36, glucose transporter (GLUT)1 and GLUT3], mRNA expression only [placenta fatty acid binding protein (FABPpm) and lipoprotein lipase (LPL)], or expression of phosphorylated and total protein forms [AMP kinase (AMPK)α, acetyl-CoA carboxylase (ACC), extracellular signal-regulated kinase (Erk)1/2, mammalian target of rapamycin (mTOR) and protein kinase B (Akt)]. On d78, but not d135, placental and fetal weights were reduced (P < 0.05) in NR vs. C ewes. Maternal circulating glucose, insulin and leptin levels were decreased in NR vs. C ewes on d78 (P < 0.05) but similar at d135. Fetal blood glucose and triglyceride levels were lower in NR vs. C ewes (P < 0.05) on d78, but similar on d135. On d78, GLUT1, FATP4, CD36 mRNA and protein expression levels, FABPpm mRNA level, and leptin protein level were all increased (P < 0.05) in COT of NR vs. C ewes. AMPK, ACC, and Erk1/2 activities were also increased (P < 0.05) in NR vs. C COT on d78. In contrast, only FATP4 was increased (P < 0.05) at both the mRNA and protein levels in COT of NR realimented vs. C ewes on d135. These data demonstrate placental adaptation to maternal NR through increasing nutrient transporter production and growth signaling activity.

Under- and over-nutrition during gestation may influence fetal hypothalamic development resulting in individuals predisposed to adverse health effects. This study examined fetuses from obese and control ewes to determine whether dam obesity alters hypothalamic expression of fetal appetite regulatory genes. A second objective was to contrast the expression of appetite regulatory genes in ewes that become the most obese to those that remained in moderate body condition on the same energy-rich diet. Multiparous, western white-faced ewes were weighed and individually fed 100% (control) or 150% (obese) of National Research Council requirements from day 60 before mating until day 75 of gestation. At day 75 of gestation, fetuses were collected and weighed. Hypothalamic tissue from fetal lambs and dams was collected and frozen for mRNA extraction. Dam obesity (P ⩾ 0.16), fetal sex (P ⩾ 0.44) or their interaction (P ⩾ 0.42) did not affect the relative expression of fetal hypothalamic regulators of appetite, including neuropeptide Y, agouti-related protein, pro-opiomelanocortin, cocaine- and amphetamine-regulated transcript and receptors for leptin. Maternal obesity at day 75 of gestation in ewes did not affect developmental mechanisms responsible for the expression of fetal appetite regulatory genes and would not be expected to predispose offspring to adult-onset obesity through disrupted appetite regulation at this developmental time point. In the ewe, appetite regulatory genes did not differ (P > 0.20) with ewe adiposity; however, expression of estrogen receptor α, but not β (P = 0.37), in the medial basal hypothalamus was greater (P = 0.04) in obese than in control ewes.

Angus × Gelbvieh rotationally crossbred yearling heifers (n = 99, yr 1; n = 105, yr 2) were used in a 2-yr randomized complete block design experiment with repeated measures to determine the effect of feeding camelina biodiesel coproducts (meal and crude glycerin) on serum concentrations of triiodothyronine, thyroxine, insulin, β-hydroxybutyrate, and glucose, as well as on growth and reproductive performance. Heifers were assigned to 1 of 15 pens, and pens were assigned initially to receive 7.03 k·•heifer(-1)·d(-1) of bromegrass hay plus 0.95 kg·heifer(-1)·d(-1) of 1 of 3 supplements for 60 d before breeding: 1) control (50% ground corn and 50% soybean meal, as-fed basis); 2) mechanically extracted camelina meal; or 3) crude glycerin (50% soybean meal, 33% ground corn, 15% crude glycerin, 2% corn gluten meal; as-fed basis). Preprandial blood samples were collected via the jugular vein on d 0, 30, and 60 of the feeding period. A 2-injection PGF(2α) protocol (d 60 and 70 of the study) was used to synchronize estrus. Heifers were artificially inseminated 12 h after estrus was first detected. Heifers not detected in estrus within 66 h received a GnRH injection and were artificially inseminated. Dietary treatment × sampling period interactions were not detected (P = 0.17 to 0.87). Dietary treatment did not affect BW (P = 0.44 to 0.59) or serum concentrations of thyroxine (P = 0.96), β-hydroxybutyrate (P = 0.46), glucose (P = 0.59), or insulin (P = 0.44). Serum concentrations of triiodothyronine were greater (P = 0.05) in heifers fed camelina meal. Additionally, dietary treatment did not affect the percentage of heifers detected in estrus before timed AI (P = 0.83), first-service pregnancy rates of those heifers detected in estrus (P = 0.97), or overall first-service pregnancy rates (P = 0.58). Heifers fed camelina meal, however, had greater (P = 0.05) first-service pregnancy rates to timed AI than did heifers fed the control and crude glycerin supplements. The cost per pregnancy was similar for heifers fed the crude glycerin or the control supplement, whereas the cost per pregnancy was the least for heifers fed camelina meal. We conclude that camelina coproducts can replace conventional corn-soybean meal supplements in the diets of developing replacement beef heifers.

We hypothesized that body condition score (BCS) at parturition and day of lactation will alter transcript abundance of mammary and adipose tissue lipogenic enzymes, as well as adipose tissue protein concentrations of lipogenic and transcription factors during early lactation in beef cows fed supplemental fat. Beginning 3d postpartum three-year-old Angus×Gelbvieh beef cows nutritionally managed to achieve a BCS of 4±0.07 (BW=479±36kg; n=18) or 6±0.07 (BW=579±53kg; n=18) at parturition were assigned to a hay diet plus low-fat control supplement or high-fat supplements (isonitrogenous and isocaloric with 5% of DMI as fat) until day 60 of lactation. At day 30 and day 60 of lactation, somatic cells from 300mL of milk were collected for ribonuclease protection assay as a measure mammary transcript abundance for lipoprotein lipase (LPL), acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and stearoyl-CoA desaturase (SCD). Abundance of mRNA was greater for FAS (P=0.02) and SCD (P=0.04) in cows of BCS 4 compared with 6. By using RT-PCR to quantify mRNA in biopsies of adipose tissue we determined that BCS 4 cows had less mRNA for LPL (P<0.001) and hormone sensitive lipase (HSL) (P=0.05) compared with BCS 6 cows. Abundance of LPL mRNA was lower (P=0.001) at day 30 postpartum compared to day 60; whereas, HSL mRNA was greater at day 30 (P<0.001). Concentration of CD36 protein was greater (P=0.03) in the BCS 6 cow adipose tissue. Both signal transducer and activator of transcription-subtype 5 (STAT-5) (P<0.001) and peroxisome-proliferator activated receptor-subtype gamma (PPAR-λ) (P=0.05) were greater at day 30 compared to day 60 postpartum. We conclude that abundance of mammary gland lipogenic enzyme mRNA was mainly affected by BCS at parturition; whereas, in adipose tissue, mRNA for enzymes for fatty acid uptake and mobilization, as well as fatty acid transport were affected by both BCS and day of lactation. Also, data suggest there was a shift in nutrient partitioning away from the mammary gland to subcutaneous adipose tissue at 60d postpartum in beef cows.

The Cell Biology Symposium on “Redox Regulation of Cell Function” was held at the Joint Annual Meeting of the American Society of Animal Science (ASAS), the American Dairy Science Association, and the Canadian Society of Animal Science in Montreal, Quebec, Canada, July 12 to 16, 2009. The ASAS Board-sponsored symposium was organized to encourage participation by scientists working in cell biology. The intent was to bring scientists involved in basic physiology and cell biology into ASAS as active participants and provide a platform to increase interactions between basic and applied scientists. The Cell Biology Symposium Committee elected to focus on reduction-oxidation (redox) regulation of cell function because the topic is relevant and has widespread application among the various disciplines within animal science. The program was organized to have the first speaker introduce the topic with subsequent speakers covering tissue-specific aspects of cellular redox reactions. The symposium began with a presentation by Guttmann (2010) discussing the maintenance of the redox state in regulation of cysteine-dependent enzymes. Cysteine-containing proteins are important to cell function because they are able to participate in a variety of reactions due, in large part, to the ability of cysteine to exist in many different oxidation states. The thiol side-chain of cysteine is a primary target of oxidation because it is particularly sensitive to all types of oxidizing agents. The major reason that cysteine is sensitive to oxidation is its ability to form anionic sulfur at physiological pH. Examples of redox-regulated enzymes were presented, and cellular mechanisms to protect against oxidative damage were discussed (Guttmann, 2010). The presentation concluded with a discussion of the relevance of redox homeostasis to animal science, which included experimental considerations, animal nutrition, aging of animals, and oxidative stress in postmortem changes of meat.

The objective of this study was to examine whether the plane of nutrition of cows at a critical time for fetal skeletal muscle and adipose tissue development would affect meat quality and carcass composition of offspring. To alter maternal nutrition, beef cows were placed on improved pasture (IP) or native range (NR) pasture from 120 to 150 through 180 to 210days of gestation. Esophageal extrusa samples collected from cows grazing IP varied from 11.1% crude protein of organic matter early in the test period to 6.0% crude protein of organic matter at the end of the grazing period; whereas, extrusa samples of cows grazing NR ranged from 6.5% crude protein of organic matter during early grazing to 5.4% crude protein of organic matter at the end of the grazing period. Steers were slaughtered and carcass characteristics were collected. Warner–Bratzler shear force was performed on longissumus steaks, western blotting was used to measure proteolysis, and myosin isoform typing was performed. Improved pasture steers had heavier live and hot carcass weights. Tenderness was greater in IP compared to NR steers. No difference in calpastatin content and troponin-T degradation was observed between treatments. The 12th rib fat thickness was greater for IP than for NR steers. Subcutaneous adipose tissue of IP steers tended to have a greater number of cells per field of view than NR steers. Data show improving nutritional status of cows during mid to late gestation affects tenderness, adipose tissue deposition and growth in steers.

The objectives were to evaluate effects of maternal nutrient restriction and stage of gestation on maternal and fetal visceral organ mass and indices of jejunal growth and vascularity in beef cows. Thirty multiparous beef cows (BW = 571 +/- 63 kg; BCS = 5.4 +/- 0.7) carrying female fetuses (d 30 of gestation) were allocated to receive a diet of native grass hay (CON; 12.1% CP, 70.7% IVDMD, DM basis) to meet NRC recommendations for BW gain during early gestation or a nutrient-restricted diet of millet straw (NR; 9.9% CP, 54.5% IVDMD, DM basis) to provide 68.1% of NE(m) and 86.7% of MP estimated requirements. On d 125 of gestation, 10 CON and 10 NR cows were killed and necropsied. Five remaining CON cows received the CON diet, and 5 NR cows were realimented with a concentrate supplement (13.2% CP, 77.6% IVDMD, DM basis) and the CON hay to achieve a BCS similar to CON cows by d 220 of gestation. Remaining cows were necropsied on d 245 of gestation. Cow BW and eviscerated BW (EBW) were less (P < 0.01) for NR than CON at d 125 but did not differ (P > 0.63) at d 245. Cows fed the CON diet had greater (P < 0.09) total gastrointestinal (GI) tract, omasal, and pancreatic weights. Stomach complex, ruminal, and liver weights were greater for CON than NR cows (P < 0.09) on d 125. Total GI, stomach complex, and pancreatic weights increased (P < 0.001) with day of gestation. Restricted cows had decreased (P = 0.09) duodenal RNA:DNA compared with CON. Duodenal DNA was less (P = 0.01) and jejunal RNA:DNA (P = 0.09) was greater for cows at d 125 vs. 245. Cow jejunal capillary area density increased with day of gestation (P = 0.02). Fetal BW and EBW were unaffected by dietary treatment (P > or = 0.32). Total GI tract and all components increased in mass with day of gestation (P < 0.001). Fetuses from NR dams had greater (P = 0.003) reticular mass at d 245 than CON fetuses. Fetuses from NR cows had greater (P = 0.02) percent jejunal proliferation at d 125 and greater (P = 0.03) total intestinal vascularity (mL) at d 245. Fetal jejunal DNA decreased (P = 0.09), RNA:DNA increased (P = 0.05), and total jejunal proliferating cells increased (P < 0.001) with day of gestation. Jejunal capillary area density, number density, and surface density were greater (P < 0.008) during late gestation. Results indicate that maternal and fetal intestines undergo changes during gestation, which can be affected by nutrient restriction and may partially explain differences observed in fetal development and postnatal performance.

Our aim in this study was to evaluate short-term (2 years) responses of several attributes of small mammal populations (species richness, abundance, diversity, and similarity) and plant community dynamics (species richness, canopy cover, above-ground biomass production, and diversity) to the mechanical disturbance associated with interseeding. Small mammal live trapping and vegetation sampling were conducted in 2004 and 2005 on replicated 1 ha study plots in a native Wyoming big sagebrush (Artemisia tridentata Nutt ssp. wyomingensis Beetle & Young)-grassland that were: 1) mechanically disturbed in April 2003 and rested from grazing during the study (mechanical); 2) rested from grazing (rested); and 3) moderately grazed by cattle (grazed). Deer mice (Peromyscus maniculatus), northern grasshopper mouse (Onychomys leucogaster), and sagebrush vole (Lemmiscus curtatus) were the primary small mammal species captured during 7776 trap nights in 2004 and 2005. Small mammal diversity was greater for the mechanical (H′ = 1.22) than the rested (H′ = 0.85) treatment with the grazed treatment intermediate. Plant community variables of species richness, diversity, similarity, and above-ground biomass production did not differ among treatments. Canopy cover of the dominant species, Wyoming big sagebrush, was reduced 20–34% by the mechanical disturbance (6.9% ± 1.0) compared to rested (8.6% ± 0.6) and grazed (10.4% ± 1.0) plots. The mechanical disturbance affected approximately 10.5% of the ground surface area but this had little impact on short-term small mammal or plant community dynamics in this rangeland ecosystem.

The objective was to compare ADG, DMI, and acute-phase response of steers supplemented or not with PUFA for 30 d prior to shipping to the feedyard. Seventy-two Angus steers weaned at 7 mo of age (d -55) were stratified by BW on d -30 of the study, and randomly allocated to 18 drylot pens (4 steers/pen). Pens were assigned to receive a grain-based supplement (avg. 1.5 kg/steer/d) without (CO) or with 0.15 kg/steer/d of a PUFA source (PF; Megalac-R, Church and Dwight, Princeton, NJ) or a SFA source (SF; Megalac, Church and Dwight). Treatment intakes were formulated to be iso-caloric, isonitrogenous, and offered daily from d -30 to d 0. Mixed alfalfa-grass hay was offered in amounts to ensure ad libitum access during the same period. On d 0, steers were loaded onto a commercial livestock trailer and transported for approximately 350 km over a 6 h period. However, steers remained in the truck for a total of 24 h before unloaded into a commercial growing lot (d 1), where steers were maintained in a single pen, managed similarly, and received a diet not containing PF or SF. Forage DMI was evaluated daily from d -30 to d -1. Shrunk BW was collected on d -33, 1, and 144 for preconditioning and growing lot ADG calculation. Blood samples were collected on d 0, 1, and 3, and analyzed for plasma concentrations of interleukin 1 and 6, tumor necrosis factor (TNF)-α, haptoglobin, ceruloplasmin, cortisol, and fatty acids. No treatment effects were detected for preconditioning ADG (P = 0.54) or G:F (P = 0.56), but DMI was often reduced for PF steers compared with CO and SF (treatment × day interaction; P < 0.01). Concentrations of PUFA were greater in PF steers compared to CO and SF prior to and after transportation (treatment × day interaction P < 0.01). Following transportation, concentration of TNF-α increased for CO, did not change for SF, but decreased for PF steers (treatment × day interaction, P < 0.01). During the growing lot, PF steers tended to have greater ADG compared to CO steers (P = 0.06) In conclusion, PUFA supplementation during preconditioning had detrimental effects on DMI, but reduced plasma concentrations of TNF-α following transportation, and improved growing lot ADG.