Orchardgrass Hay Research Articles

Effect of Biochar Type and Size on<i> in Vitro </i>Rumen Fermentation of Orchard Grass Hay

Biochar, a byproduct from the biofuels industry, may be a potential feed additive in ruminant diets due to possible improvements in microbial fermentation. Therefore, the objective of this study was to determine the nutritive value, in vitro digestibility, volatile fatty acid (VFA) production, and gas production of biochar inclusion to an orchard grass (Dactylis glomerata) basal diet. The study was designed as a 3 × 2 factorial arrangement with 3 different biochar sources and 2 biochar processed sizes as the main effects factors. Experimental treatments were biochar from 3 different tree types: 1) Chestnut Oak (Quercus prinus L.; CO), 2) Yellow Poplar (Liriodendron tulipifera; YP), or 3) White Pine (Pinus strobus L.; WP), and processed at 2 different biochar particle sizes: a) 178 μm (Coarse). Biochar was added to the basal diet of orchard grass hay (872.35 g/kg of DM, 98.31 g/kg of CP, and 704.02 g/kg of aNDF, DM basis) at a rate of 81 g/kg DM. Biochar residual ash content was greater (P P P = 0.01) with lower aNDF content in both WP sizes compared with their respective biochar type and size. Gas production was not influenced (P = 0.23) by biochar tree type; however, gas production was increased (P = 0.05) by Fine particle size compared with Coarse biochar. The in vitro true digestibility (IVTD) of orchard grass hay was increased (P = 0.01) by the inclusion of Fine biochar particle size compared with Coarse particle size. Additionally, in vitro CP true digestibility (DCP) exhibited a type × size interaction (P = 0.01). Crude protein digestibility was lower for Fine particle-sized CO and WP biochar sources compared with Coarse particle-sized CO and WP (P ≤ 0.004). However, DCP was not different between Coarse and Fine particle-sized YP biochar (P = 0.70). Volatile fatty acids (acetate, propionate, and butyrate) were not altered by biochar type (P ≥ 0.66) or particle size (P ≥ 0.19). These results indicate that both tree type and particle size of biochar may need to be carefully considered before incorporating into a ruminant diet. Furthermore, Fine particle-sized biochar may be the most effective to incorporate as a feed additive in a ruminant diet based on digestibility parameters.

Injecting Poultry Litter into Orchardgrass Hay

ABSTRACTTraditional surface application of poultry litter leaves nutrients vulnerable to loss through volatilization and runoff. However, injection can increase capture of these nutrients in agricultural fields. Therefore, a field experiment was conducted to determine the effects of poultry litter injection on orchardgrass (Dactylis glomerata L.) hay yield and quality. Poultry litter was injected or surface applied using the Subsurfer poultry litter injector at the recommended agronomic rate (high) and half that rate (low) in 2012 and 2013 in an established field of orchardgrass. Soil was sampled to 15 cm and analyzed for soil nitrate. No significant differences in soil nitrate were detected between treatments. Although not always statistically significant, first cutting orchardgrass yields tended to be greater with surface litter application. Injected treatments had greater protein concentrations than their respective surface treatment, showing greater nitrogen uptake, when protein was weighted by yield. Protein was the same for high surface and low injected treatments showing that similar nitrogen (N) uptake was achieved.

Alfalfa hay induced primary photosensitization in horses

Photosensitization, also known as photodermatitis, occurs when phototoxic or photoactive substances accumulate in the skin and interact with sunlight to result in an often severe, crusting, itching or painful dermatitis in unpigmented and/or lightly haired areas of the skin. Primary photosensitization, caused by direct ingestion of photosensitizing agents, has been reported anecdotally in horses after ingestion of alfalfa hay. Between 2004 and 2014, several large outbreaks of primary photosensitization in horses fed primarily alfalfa hay were investigated in California. Alfalfa hay samples were collected and carefully examined for the presence of known photosensitizing plants and pesticide residues but none were identified. Select hay samples were evaluated for unusual fungal infestation and for phototoxicity assay using a specific Candida albicans assay; results were negative. In the 2004 outbreak, a feeding study was conducted with three horses exclusively fed alfalfa hay that was suspected to have caused the outbreak. Two weeks after ingestion of alfalfa hay, two horses developed several lesions in non-pigmented skin characterized as chronic ulcerative and necrotizing dermatitis with superficial vasculitis, which was consistent with photosensitization. In the 2014 outbreak, seven different implicated alfalfa hay samples were analyzed for chlorophyll a and b, and pheophorbide a. These compounds had been suspected to play a role in alfalfa-induced primary photosensitization. The chlorophyll contents ranged from 0.90 to 2.30 mg/g in the alfalfa hay samples, compared to 1.37 and 2.94 mg/g in locally grown alfalfa and orchard grass hay. The pheophorbide a levels ranged from 3.36 to 89.87 µg/g in alfalfa samples compared to 81.39 and 42.33 µg/g in control alfalfa and orchard grass hay samples. These findings eliminate chlorophyll a, chlorophyll b, and pheophorbide a as possible causes for alfalfa-hay induced primary photosensitization.

Ensiling characteristics of distillers wet grains with corn stalks and determination of the feeding potential for dairy heifers

ABSTRACT The characteristics and feeding potential of corn distillers wet grains with solubles ensiled with corn stalks were evaluated in a 2-part experiment. Six individual batches of 66.7% distillers wet grains with solubles and 33.3% corn stalks (on an as-fed basis) were mixed and ensiled in 2 plastic silage bags. A set of 3 batches was left untreated (UNT), and the other set of 3 batches was treated (TRT) with a silage additive. Silos were sampled for analysis on d 0, 7, 14, and 21 after ensiling. The ensiling study was followed by a 6-wk randomized complete block design feeding study using 12 dairy heifers (initial BW of 213.8 ± 3.03 kg) with 3 diets. Treatment diets were (1) control (CON) consisting of 30.3% grain mixture and 69.7% alfalfa and orchard grass hay, (2) 99% UNT blend and 1% mineral premix, and (3) 99% TRT blend and 1% mineral premix on a DM basis. In the ensiling study, blends were similar in DM, CP, ADF, pH, lactic acid, and acetic acid. In the feeding study, body frame measurements and ADG were similar among heifers fed all diets. Dry matter intakes were greater and G:F was less (P

Orchardgrass die‐off: How harvest management and heat stress may be reducing the persistence of orchardgrass hay stands

Orchardgrass die‐off: How harvest management and heat stress may be reducing the persistence of orchardgrass hay stands

Effects of grass hay proportion in a corn silage-based diet on rumen digesta kinetics and digestibility in dairy cows.

In this study, we aimed to evaluate the effects of six levels of orchardgrass hay (GH) proportion (0%, 10%, 20%, 30%, 40% or 50% of dry matter) in finely chopped corn silage (CS)-based diets on digesta kinetics of CS and GH in the rumen. Six non-lactating, rumen-cannulated Holstein cows were used in a 6 × 6 Latin square design. Ruminal digesta kinetics was measured by ruminal dosing of feed particle markers (dysprosium for CS, erbium for GH) followed by fecal sampling. The increase of GH proportion had a quadratic effect (P < 0.01) on total tract digestibility of neutral detergent fiber (NDF) and acid detergent fiber. The proportion of GH did not affect the particle size distribution of rumen digesta, total weight of dry matter or NDF in the rumen. The rates of large particle size reduction in the rumen for CS tended to increase linearly with increasing GH proportion (P = 0.077). A quadratic effect (P < 0.05) was found with increasing the GH proportion for the ruminal passage rate of small GH particles, but not for CS particles. The results suggested that associative effects between CS and GH could be generated on rumen digesta kinetics when cows were fed a CS-based diet with an increased proportion of GH.

Bacterial communities in the rumen of Holstein heifers differ when fed orchardgrass as pasture vs. hay.

The rich and diverse microbiota of the rumen provides ruminant animals the capacity to utilize highly fibrous feedstuffs as their energy source, but there is surprisingly little information on the composition of the microbiome of ruminants fed all-forage diets, despite the importance of such agricultural production systems worldwide. In three 28-day periods, three ruminally-cannulated Holstein heifers sequentially grazed orchardgrass pasture (OP), then were fed orchardgrass hay (OH), then returned to OP. These heifers displayed greater shifts in ruminal bacterial community composition (determined by automated ribosomal intergenic spacer analysis and by pyrotag sequencing of 16S rRNA genes) than did two other heifers maintained 84 d on the same OP. Phyla Firmicutes and Bacteroidetes dominated all ruminal samples, and quantitative PCR indicated that members of the genus Prevotella averaged 23% of the 16S rRNA gene copies, well below levels previously reported with cows fed total mixed rations. Differences in bacterial community composition and ruminal volatile fatty acid (VFA) profiles were observed between the OP and OH despite similarities in gross chemical composition. Compared to OP, feeding OH increased the molar proportion of ruminal acetate (P = 0.02) and decreased the proportion of ruminal butyrate (P < 0.01), branched-chain VFA (P < 0.01) and the relative population size of the abundant genus Butyrivibrio (P < 0.001), as determined by pyrotag sequencing. Despite the low numbers of animals examined, the observed changes in VFA profile in the rumens of heifers on OP vs. OH are consistent with the shifts in Butyrivibrio abundance and its known physiology as a butyrate producer that ferments both carbohydrates and proteins.

Vasoconstrictive responses by the carotid and auricular arteries in goats to ergot alkaloid exposure.

A fungal endophyte (Neotyphodium coenophialum) infects most plants of “Kentucky 31” tall fescue (Lolium arundinaceum) and produces ergot alkaloids that cause persistent constriction of the vascular system in grazing livestock. Consequently, animals undergoing this toxicosis cannot regulate core body temperature and are vulnerable to heat and cold stresses. An experiment was conducted to determine if the caudal and auricular arteries in goats (Capra aegagrus hircus) vasoconstrict in response to ergot alkaloids. Seven, rumen fistulated goats were fed ad libitum orchardgrass (Dactylis glomeratia) hay and ruminally infused with endophtye-free seed (E−) for a 7-day adjustment period. Two periods followed with E− and endophyte-infected (E+) seed being randomly assigned to the 2 goat groups in period 1 and then switching treatments between groups in period 2. Infused E+ and E− seed were in equal proportions to the hay such that concentrations of ergovaline and ergovalanine were 0.80 μg per g dry matter for the E+ treatment. Cross-sections of both arteries were imaged using Doppler ultrasonography on days 0, 2, 4, 6, 8, and 12 in period 1 and on days 0, 1, 2, 3, 6, 7, and 9 in period 2. Differences from average baseline areas were used to determine presence or absence of alkaloid-induced vasoconstriction. Carotid arteries initiated constriction on imaging day 2 in both periods, and auricular arteries initiated constriction on imaging day 2 in period 1 and on day 6 in period 2. Luminal areas of the carotid arteries in E+ goats were 46% less than baseline areas in both periods after vasoconstriction occurred, whereas auricular arteries in E+ goats were 52% less than baseline areas in period 1 and 38% in period 2. Both arteries in E+ goats in period 1 relaxed relative to baseline areas by imaging day 2 after they were switched to the E− treatment. Results indicated that goats can vasoconstrict when exposed to ergot alkaloids that could disrupt their thermoregulation.

Effect of corn silage particle size and supplemental hay on rumen pH and feed preference by dairy cows fed high-starch diets

The objectives of this experiment were to determine the effects of corn silage particle size and supplemental hay on rumen pH and feed preference in lactating dairy cows experiencing a bout of subacute ruminal acidosis (SARA). In this study, 12 lactating (8 ruminally cannulated), multiparous Holstein cows averaging 91±40d in milk and weighing 695±95kg (mean ± SD) were randomly assigned to a replicated 4×4 Latin square. During each of the four 21-d periods, animals were offered 1 of 4 diets that were chemically similar but varied in corn silage particle size and supplemental second cutting orchardgrass hay: short corn silage total mixed ration (TMR; ST); short corn silage TMR with 5.6% supplemental hay (SH); long corn silage TMR (L); and long corn silage TMR with 5.6% supplemental hay (LH). Cows were allowed to adapt to this feeding scheme for 14d, and cannulated cows were then subjected to a rumen challenge to induce a bout of SARA by restricting feed before the challenge and providing 4kg of ground wheat via the rumen cannula. Although baseline pH was low, the SARA challenge lowered ruminal pH further for all cows regardless of diet. Daily average rumen pH decreased from 5.44 and 5.45 to 5.33 and 5.38 for ST and SH, respectively, and from 5.64 and 5.54 to 5.47 and 5.39 for L and LH, respectively, from baseline to challenge phase. Following the rumen challenge, rumen concentrations of acetate, propionate, butyrate, and valerate increased. Decreasing corn silage particle size significantly increased TMR and total DMI during all phases of the model. Feeding short corn silage TMR increased milk, protein, and lactose yields. Cows fed supplemental hay had increased fat yield and protein concentration in the milk and responded minimally to the effects of particle size selection when challenged with SARA. Cows consuming short corn silage TMR changed feed preference for longer forage particles during the course of the SARA challenge. During the recovery phase, however, cows refused an average of 13.5% of the offered TMR and 78.7% of the supplemental hay. These results indicate that cows did not prefer the supplemental hay regardless of corn silage particle size during a bout of SARA, which may have been due to the possible adaptation of a low ruminal pH throughout the study.

Breakeven Cost of Irrigating Bermudagrass, Tall Fescue, and Orchardgrass Hay Production in Tennessee

Little is known about the economic feasibility of irrigating cool‐ and warm‐season grass species for hay production in the southeastern United States. The objective of this study was to determine the breakeven cost of irrigating bermudagrass [Cynodon dactylon (L.) Pers.], tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., formerly Festuca arundinacea Schreb.], and orchardgrass (Dactylis glomerata L.) for hay production in Tennessee. Yield response to three irrigation levels during three harvest periods was estimated for the three grass species using data obtained from a 5‐yr study in a mixed model analysis. Partial budgets were developed to calculate annual net returns for irrigated and unirrigated hay production and to calculate the annual breakeven cost of irrigation for each grass. Orchardgrass and tall fescue hay yields negatively responded to irrigation during the spring harvest but positively responded for the summer and fall harvests. Similarly, bermudagrass hay yield positively responded to irrigation during the summer and fall harvests. For all three grass species, hay yield was greatest at the highest irrigation level (3.05 cm wk−1) during the fall harvest only. The breakeven costs of irrigation for hay production ranged between US$59 and US$87 ha−1 for orchardgrass, between US$66 and US$136 ha−1 for tall fescue, and between US$222 and US$335 ha−1 for bermudagrass. Results suggest that a producer would be more likely to increase net returns by irrigating bermudagrass than irrigating cool‐season grass species in the southeastern United States.

Transcriptional regulators transforming growth factor-β1 and estrogen-related receptor-α identified as putative mediators of calf rumen epithelial tissue development and function during weaning

Molecular mechanisms regulating rumen epithelial development remain largely unknown. To identify gene networks and regulatory factors controlling rumen development, Holstein bull calves (n=18) were fed milk replacer only (MRO) until 42d of age. Three calves each were euthanized at 14 and 42d of age for tissue collection to represent preweaning, and the remaining calves were provided diets of either milk replacer + orchard grass hay (MH; n=6) to initiate weaning without development of rumen papillae, or milk replacer + calf starter (MG; n=6) to initiate weaning and development of rumen papillae. At 56 and 70d of age, 3 calves from the MH and MG groups were euthanized for collection of rumen epithelium. Total RNA and protein were extracted for microarray analysis and to validate detected changes in selected protein expression, respectively. As expected, calves fed MRO had no rumen papillae and development of papillae was greater in MG versus MH calves. Differentially expressed genes between the MRO diet at d 42 (preweaning) versus the MG or MH diets at d 56 (during weaning) were identified using permutation analysis of differential expression. Expression of 345 and 519 transcripts was uniquely responsive to MG and MH feeding, respectively. Ingenuity Pathway Analysis (Qiagen, Redwood City, CA) indicated that the top-ranked biological function affected by the MG diet was the cell cycle, and TFGB1, FBOX01, and PPARA were identified as key transcriptional regulators of genes responsive to the MG diet and associated with development of rumen papillae. Increased expressions of TGFB1 mRNA and protein in response to the MG diet were confirmed by subsequent analyses. The top-ranking biological function affected by the MH diet was energy production. Receptors for IGF-1 and insulin, ESRRA, and PPARD were identified by ingenuity pathway analysis as transcriptional regulators of genes responsive to the MH diet. Further analysis of TGFB1 and ESRRA mRNA expression in rumen epithelium obtained from a separate ontogenic study of Holstein calves (n=26) euthanized every 7d from birth to 42d of age showed increases in transcript expression with advancing age, supporting their roles in mediating rumen epithelial development and function during weaning. Additional evaluation of gene expression in the rumen epithelium of adult cows ruminally infused with butyrate also suggested that observed changes in ESRRA mRNA expression in developing calf rumen may be mediated by increased butyrate concentration. Our results identify TGFB1 and ESRRA as likely transcriptional regulators of rumen epithelial development and energy metabolism, respectively, and provide targets for modulation of rumen development and function in the growing calf.

Fibre digestibility, abundance of faecal bacteria and plasma acetate concentrations in overweight adult mares.

The purpose of the present study was to compare digestibility of grass hay, faecal and plasma volatile fatty acid (VFA) concentrations, and faecal bacterial abundance in overweight and moderate-condition mares. Five overweight adult mixed-breed mares and five adult mixed-breed mares in moderate condition were housed individually and limit-fed orchard grass (Dactylis glomerata) hay at 20g/kg body weight (as fed) daily for 14 d. Forage DM and fibre digestibility were determined using AOAC methods; digestible energy was measured using bomb calorimetry; plasma and faecal VFA concentrations were determined by use of GC and MS; faecal Firmicutes, Bacteroidetes, Fibrobacter succinogenes, Ruminococcus flavefaciens and total bacteria abundance was determined by quantitative real-time PCR using previously designed phylum-specific 16S ribosomal RNA gene primers. No differences in hay digestibility, faecal VFA concentrations or faecal bacterial abundance were detected between overweight and moderate-condition mares. Mean plasma acetate concentrations were higher (P=0·03) in overweight (1·55 (range 1·43-1·65) mmol/l) v. moderate-condition (1·39 (range 1·22-1·47) mmol/l) mares. We conclude that the higher plasma acetate in overweight mares should be further investigated as a potential link between gut microbes and obesity in horses.

Influence of drinking water with quebracho tannin on intake of endophyte-infected tall fescue by cattle

Endophyte-infected tall fescue (TF) contains alkaloids that can adversely affect the productivity and health of livestock. These effects are exacerbated when livestock forage on TF grown in monoculture, but they are mitigated when livestock forage on pastures that contain TF in mixture with tannin-containing plants, evidently because tannins bind to the steroidal and protein-like alkaloids found in TF. Cattle and sheep will drink water that contains up to 20g/L condensed tannins. We hypothesized that cattle (n=8) offered water containing quebracho tannins (10g/L) would eat more TF than cattle (n=8) offered plain water. During the trial, cattle were offered 9kg/(animal*d) of freshly harvested TF. Cattle drank less water with than without tannins (17.7kg/d vs. 24.6kg/d; P<0.005), and they tended to eat less TF (4.3kg/d vs. 5.1kg/d; P=0.10). No differences in weight change occurred during the trial (P=0.83) or between groups (P=0.70). The negative impacts of tannins on water intake likely depressed intake of TF, but the lower intakes of tannin water and TF did not adversely affect BW. On the one hand, water restriction and dehydration reduce food intake and any agent that limits intake of water will adversely affect food intake and animal performance. On the other hand, while cattle with fresh water maintained BW during the trial, so did cattle with tannin water, which suggests the tannin may have benefited the cattle fed a diet of orchard grass hay and TF. Further studies are required to assess the role of tannins in water on both the intake and performance of livestock eating TF.

Interrelationships among selenium status, antioxidant capacity and oxidative stress in the horse

Interrelationships among selenium status, antioxidant capacity and oxidative stress in the horse

Eicosapentaenoic and docosahexaenoic acids increase insulin sensitivity in growing steers1

An experiment was conducted to determine the effect of dietary n-3 long chain PUFA on insulin sensitivity in growing steers. Steers (n = 12, initial BW = 336.3 kg, SEM = 7.7) were adapted to a basal diet that was 70% concentrate mix and 30% orchardgrass hay. Steers were fed a daily amount of 0.26 Mcal ME per kg BW (0.75). After 3 wk steers were transitioned to 1 of 2 treatment (Trt) diets (n = 6 per diet) containing added Ca salts of fatty acids at 4% of DM using a source of fat that was enriched in n-3 fatty acids, including eicosapentaenoic acid and docosahexaenoic acid (FOFA), or a source of fat without n-3 fatty acids and a greater percentage of C16:0 and C18:1 (LCFA). Three intravenous (i.v.) glucose tolerance tests (IVGTT) were conducted, 1 during the basal diet, and 2 after transition to treatment diets at time 1 (T1; d 4 Trt) and time 2 (T2; d 39 Trt). Three i.v. insulin challenge tests (IC) were conducted the day after each IVGTT. Measurements on the basal diet were used as covariates. For IVGTT, there was a diet by time interaction (P < 0.05) for glucose area under the response curve (AUC). The AUC50 (mM glucose × 50 min) at T1 was less (P = 0.02) for LCFA (126.2) than FOFA (151.8), AUC50 at T2 tended to be greater (P = 0.07) for LCFA (165.9) than FOFA (146.0). Preinfusion insulin concentration was greater (P < 0.001) before the IVGTT and IC for steers fed LCFA (40.4 and 40.2 µIU/mL) than for steers fed FOFA (23.7 and 27.1 µIU/mL), respectively. Glucose clearance did not differ between treatments. For IC, minimum glucose concentration was greater (P = 0.02) and glucose AUC150 was less (P < 0.01) for steers fed LCFA than for steers fed FOFA. Values for glucose concentration were 1.8 mM and 1.5 mM and for AUC150 (mM glucose × 150 min) were 203.1 and 263.6 for steers fed LCFA and FOFA, respectively. Insulin clearance (fraction/min) was greater (P < 0.01) for steers fed LCFA (0.121) than FOFA (0.101). The insulin AUC60 (µIU/mL × 60 min) postinfusion was less for LCFA (17,674) than FOFA (19,997), and tended to be greater (P = 0.06) at T1 (19,552) than T2 (18,119). Plasma NEFA concentrations at T2 during IVGTT were greater (P < 0.05) in steers fed FOFA than in steers fed LCFA. The results indicated that supplementing with long-chain n-3 PUFA (FOFA) increased insulin sensitivity in growing steers compared with feeding a supplement with greater concentration of SFA (LCFA).

Addition of high concentration of inorganic selenium in orchardgrass (Dactylis glomerata L.) hay diet does not interfere with microbial fermentation in mixed ruminal microorganisms in continuous cultures

ABSTRACT The current literature lacks information on ruminal microbial metabolism in response to high selenium (Se) concentration in the diet. The current study was performed to investigate changes in ruminal fermentation when high concentration of Se was administered in mixed ruminal cultures in fermentors. Two mature beef cows, fitted with a rumen cannula, were grazed on tall-fescue pasture and used as donor animals for ruminal contents. Filtered ruminal contents were allowed 11 d of adaptation to diets followed by 3 d of data collection. A dual-flow continuous culture system was used in a completely randomized design (n = 4) to test 2 dietary treatments: control (no Se addition) and 50 mg/kg of Se addition. Orchardgrass hay (20 g of DM/d) containing 0.12 mg/kg of Se was added to the fermentors in 2 equal portions at 0800 and 1700 h. Selenium (sodium selenate) was added to the Se-addition treatment by gradually increasing the concentration from 2 to 50 mg/kg over the 11-d adaptation period. Culture pH averaged 6.04 and was not affected by treatment. Total VFA concentration averaged 52.2 and 55.5 mM in the control and Se treatment cultures, respectively, and addition of Se did not affect the total VFA concentration. Molar proportions of acetate and propionate did not differ because of Se addition, resulting in a similar acetate-to-propionate ratio. However, addition of Se tended to increase (P = 0.09) ammonia-N concentration and methane production (P = 0.10). Selenate-respiring microorganisms were detected by the most probable number enumeration technique in 3 of the 4 replications receiving Se. Addition of 50 mg/kg of Se in orchardgrass-hay diet had no negative effects on ruminal fermentation, as was observed in similar culture pH and VFA concentration. However, addition of Se affected microbial metabolism in the mixed cultures by increasing ammonia-N concentration and methane production. Overall data in this study suggest that the addition of Se up to 50 mg/kg would not interfere with in vitro ruminal metabolism by microbiota and that some adaptation of Se-reducing microbes may occur.

Gene expression in bovine rumen epithelium during weaning identifies molecular regulators of rumen development and growth

During weaning, epithelial cell function in the rumen transitions in response to conversion from a pre-ruminant to a true ruminant environment to ensure efficient nutrient absorption and metabolism. To identify gene networks affected by weaning in bovine rumen, Holstein bull calves were fed commercial milk replacer only (MRO) until 42days of age, then were provided diets of either milk + orchardgrass hay (MH) or milk + grain-based calf starter (MG). Rumen epithelial RNA was extracted from calves sacrificed at four time points: day 14 (n = 3) and day 42 (n = 3) of age while fed the MRO diet and day 56 (n = 3/diet) and day 70 (n = 3/diet) while fed the MH and MG diets for transcript profiling by microarray hybridization. Five two-group comparisons were made using Permutation Analysis of Differential Expression® to identify differentially expressed genes over time and developmental stage between days 14 and 42 within the MRO diet, between day 42 on the MRO diet and day 56 on the MG or MH diets, and between the MG and MH diets at days 56 and 70. Ingenuity Pathway Analysis (IPA) of differentially expressed genes during weaning indicated the top 5 gene networks involving molecules participating in lipid metabolism, cell morphology and death, cellular growth and proliferation, molecular transport, and the cell cycle. Putative genes functioning in the establishment of the rumen microbial population and associated rumen epithelial inflammation during weaning were identified. Activation of transcription factor PPAR-α was identified by IPA software as an important regulator of molecular changes in rumen epithelium that function in papillary development and fatty acid oxidation during the transition from pre-rumination to rumination. Thus, molecular markers of rumen development and gene networks regulating differentiation and growth of rumen epithelium were identified for selecting targets and methods for improving and assessing rumen development and function, particularly in the growing calf.

Effects of feeding wheat straw or orchardgrass at ad libitum or restricted intake during the dry period on postpartum performance and lipid metabolism

The objectives of this study were to investigate the effects of forage source [wheat straw (WS) or orchardgrass hay (OG)] and total amount of diet dry matter fed [ad libitum or restricted to 70% of predicted dry matter intake (DMI)] prepartum on postpartum performance. The study design was a 2×2 factorial design with 10 cows per treatment. Treatments were WS total mixed ration (TMR) ad libitum, OG TMR ad libitum, WS TMR restricted, and OG TMR restricted. The WS TMR (dry matter basis) contained 30% WS, 20.7% corn silage, 10.0% alfalfa hay, 18.2% ground corn, 16.8% soybean meal, and 4.3% molasses mineral mix (14.7% CP, 1.5Mcal/kg of net energy for lactation, 37.0% neutral detergent fiber). The OG TMR contained 30% OG, 46.2% corn silage, 10.0% alfalfa hay, 9.5% soybean meal, and 4.3% molasses (14.2% CP, 1.5Mcal/kg of net energy for lactation, 41.0% neutral detergent fiber). Cows received 1 lactation diet after calving (17.7% CP, 1.6Mcal/kg of net energy for lactation, 27.3% neutral detergent fiber). Total diet DMI prepartum was higher for ad libitum than for restricted as designed, but forage source had no effect on DMI. Total tract apparent digestibilities of DM and NDF were greater for OG than for WS. Postpartum DMI expressed as a percentage of body weight for the first week of lactation was higher for ad libitum than for restricted diets. Postpartum DMI during the first 30d of lactation was higher for OG than for WS, but no effect was observed for the amount fed prepartum. Milk yield during the first week of lactation was higher for OG than for WS; however, during the first 30d, 3.5% fat-corrected milk yield and yield of milk fat were highest for OG TMR restricted and WS TMR ad libitum. Prepartum treatments had a limited effect on pre- and postpartum lipid metabolism; however, cows fed WS TMR ad libitum had the highest postpartum β-hydroxybutyrate. Eating behavior was observed by 10-min video scans of 24-h video surveillance for 5d pre- and postpartum. Prepartum eating time and eating bouts tended to be greater by WS than for OG, and postpartum eating time per kilogram of neutral detergent fiber intake tended to be greater for WS than for OG. Results indicate that forage source and amount of DM fed prepartum affected postpartum performance and tended to alter the behavior of cows in tie-stall barns.

Postweaning performance of heifers fed starter with and without hay during the milk-feeding period

This study assessed the carryover effects of providing forage during the milk-feeding period on postweaning feed intake and growth of heifers. At 11wk of age, heifers previously (3 to 77d of age) reared on starter (n=8) or starter plus grass hay (n=8) were switched to a single diet consisting of restricted amounts of concentrate [60% of the starter required to support daily body weight (BW) gain of 800g] with ad libitum access to coarsely chopped orchardgrass hay. Feed intake and growth were measured from 11 to 18wk of age. Starter dry matter (DM) intake averaged 2.14±0.15kg/d for both treatments. Forage consumption and total (starter plus hay) DM, neutral detergent fiber, crude protein, and metabolizable energy intakes were greater in heifers previously fed forage compared with those provided no forage. Initial and final BW were similar for the 2 treatments (108.2±9.1 and 149.6±9.3kg, respectively). Overall average daily gain in heifers previously fed starter alone (0.92±0.05,kg/d) tended to be greater than those previously fed starter plus hay (0.79±0.06,kg/d). Total DM intake (starter plus hay) was lower in heifers previously fed starter alone than those fed starter plus hay (3.55±0.13 vs. 4.08±0.15kg/d, respectively). Feed efficiency (BW gain/DM intake) after switching to a common diet was greater in calves previously fed starter alone than in those previously fed starter plus hay (0.26±0.01 vs. 0.19±0.01, respectively). However, heifers provided access to hay had a smaller body barrel (an indicator of gut fill) at 15wk (127.7±1.7 vs. 134.3±2.7cm) and 17wk (132.4±1.9 vs. 141.0±2.2cm) of age and had greater blood β-hydroxybutyrate (0.22±0.04 vs. 0.32±0.04mmol/L) compared with heifers that did not have access to hay earlier in life. These results indicate that provision of hay early in life promotes forage intake when heifers are switched to a high forage diet. However, greater feed consumption did not translate into live BW gain. Higher feed efficiency after switching to a common diet in heifers previously fed starter alone compared with those fed starter plus hay must be viewed with caution because intestinal content likely varied between treatment groups.

The Effect of Soaking on Protein and Mineral Loss in Orchardgrass and Alfalfa Hay

Nonstructural carbohydrates are usually targeted for reduction during hay soaking, however, other essential nutrients may also be lost. The objectives of this research were to determine the impact of water temperature and time of soaking on reduction of protein and minerals from alfalfa and orchardgrass hay. The experimental design was a randomized complete block with six replications (n = 192). Hay types included bud and flowering alfalfa (Medicago sativa L) and vegetative and flowering orchardgrass (Dactylis glomerata L). Flakes were soaked for 15, 30, and 60 minutes in 25 L of cold (22°C) and warm (39°C) water, and for 12 hours in cold water. Changes in crude protein concentration after soaking had no effect (P > .05) on alfalfa-bud or flowering orchardgrass hay. However, crude protein concentration increased (P = .02) as soaking length increased in vegetative orchardgrass, and decreased as soaking length increased (P < .001) in flowering alfalfa hay. Soaking did not affect (P > .05) calcium (Ca) concentrations in flowering alfalfa and orchardgrass; however, Ca (P < .001) was reduced as soaking length increased in alfalfa-bud and vegetative orchardgrass hay. Reductions in phosphorus (P), potassium, and magnesium concentrations occurred with longer soaking times, resulting in high Ca:P ratios after 12 hours of soaking (P < .001). Soaking for 15-60 minutes did not result in nutrient deficiencies based on the requirements of a 500-kg horse in light work. However, supplementation of P after feeding hay soaked for 12 hours would be necessary to address high Ca:P ratios.