Alfalfa Hay Cubes Research Articles

The mitigating effect of feeding lucerne hay cubes supplemented with an optimal combination of nitrate with l-cysteine on enteric methane emission in sheep

The combination of optimal nitrate and l-cysteine to safely mitigate rumen methane (CH4) emissions in ruminants was studied in an open-circuit respiration head-hood system using four rumen-fistulated Suffolk wethers in a 4 × 4 Latin square design. Four treatments were set up Control: fed on lucerne hay cubes without nitrate and l-cysteine, Nitrate: fed on lucerne hay cubes with 0.18 % NO3−-N in dry matter (DM)), N + Cys-H: fed on lucerne hay cubes supplemented with 0.18 % NO3−-N and 0.74 % l-cysteine (equivalent to half the upper limit of effective S requirement in DM), and N + Cys-Q: fed on lucerne hay cubes supplemented with 0.18 % NO3−-N and 0.37 % l-cysteine (equivalent to 1/4 of the upper limit of effective S requirement in DM). In this experiment, the ingested nitrate at a subclinical concentration/s (0.18 % in DM) increased by 11.2 % mean methemoglobin value and alleviated rumen methanogenesis by 47 %. Administration of l-cysteine set at 0.74 % and 0.37 % in DM reduced by 68 % and 58 % methemoglobin formed by nitrate alone, respectively (P < 0.05). However, daily mitigation of CH4 emissions decreased by 35 % with the addition of l-cysteine at both addition concentration/s compared with Control.The results of this study suggest that mitigation of enteric methane emissions by the combination of nitrate and l-cysteine can be achieved by feeding diets in which the nitrate content is maintained at around 0.18 % NO3−-N in DM and l-cysteine addition is adjusted to 0.37–0.74 % in DM. This method would be recommended as a safe, efficient, and practical way to mitigate enteric CH4 emissions leading to increased productivity while reducing the increased N excretion that causes N2O emissions.

PS-3 Effects of Feeding Rates on Diflubenzuron Efficacy Against Filth Flies (Diptera: Muscidae) in Manure of Beef Heifers

Abstract The objective of the current study is to determine the effect of feeding rates on the efficacy of diflubenzuron against filth fly development in the manure of beef heifers. Twelve Angus × Hereford crossbred heifers (263 kg ± 16.2 kg BW) were used in a completely randomized design and heifers were assigned to a 2 x 2 factorial arrangement of treatments to evaluate the efficacy of diflubenzuron against horn flies Haematobia irritans (L.), stable flies Stomoxys calcitrans and house fly Musca domestica utilizing fecal bioassays. Treatments consisted of 2 insecticidal treatments [Diflubenzuron (DFB; 0.10 mg per kg BW) and no DFB (CNT)] in a factorial arrangement with 2 dietary fed regimens [1.5% BW alfalfa hay cubes and 3.0% BW alfalfa hay cubes]. All heifers receiving DFB treatments were dosed daily beginning on day 0 and continuing through day 7. Manure samples were collected daily prior to DFB offering and for 11 consecutive days. Efficacy calculations were developed utilizing standard filth fly fecal bioassays accounting for control performance. A treatment × day interaction (P ≤ 0.01) was observed for all species largely associated with the presence of DFB and associated with the on-set of efficacy (day 0–2) and wash out (day 8–10) of the product. Feeding regimen did not (P &amp;gt; 0.05) influence DFB performance against any of the fly species evaluated. Formulations of DFB appear to handle a wide range of animal intake scenarios under controlled situations.

Nutrient digestibility, fecal output of fractionated proteins, and ruminal fermentation parameters of goats fed a diet supplemented with spent green tea and black tea leaf silage.

Spent green and black tea leaf silage (GTS and BTS, respectively) was offered as a protein supplement to goats to examine in vivo digestibility, nitrogen balance, urinary excretion of purine derivatives, and ruminal fermentation. Four castrated goats were fed a basal diet supplemented with alfalfa hay cube (AHC), GTS, or BTS in a 4 × 4 Latin square design. Digestibilities of various nutrients except for nitrogen (N) fraction were unaffected by the type of supplement. Digestibility of acid detergent insoluble N (ADIN) in BTS treatment was a negative value and significantly lower than those in other treatments. Urinary N output and retained N were not significantly affected by the diets. The fecal output of neutral detergent insoluble nitrogen (NDIN) and ADIN in the BTS treatment was significantly higher than those in other treatments. Urinary excretion of purine derivatives was not affected by the treatments. Ruminal NH3 -N concentration in AHC and GTS treatments were not significantly different, but that in the BTS treatment was significantly lower than others. These results indicated that GTS is substitutable for AHC as a protein supplement, whereas BTS was able to bind proteins tightly in the digestive tract, which lowered ruminal N degradability and increase fecal N output.

The effect of temporal variation in feed quality and quantity on the diurnal feeding behaviour of dairy cows

The diurnal feeding patterns of dairy cows affects the 24 h robot utilisation of pasture-based automatic milking systems (AMS). A decline in robot utilisation between 2400 and 0600 h currently occurs in pasture-based AMS, as cow feeding activity is greatly reduced during this time. Here, we investigate the effect of a temporal variation in feed quality and quantity on cow feeding behaviour between 2400 and 0600 h as a potential tool to increase voluntary cow trafficking in an AMS at night. The day was allocated into four equal feeding periods (0600 to 1200, 1200 to 1800, 1800 to 2400 and 2400 to 0600 h). Lucerne hay cubes (CP = 19.1%, water soluble carbohydrate = 3.8%) and oat, ryegrass and clover hay cubes with 20% molasses (CP = 11.8%, water soluble carbohydrate = 10.7%) were offered as the ‘standard’ and ‘preferred’ (preference determined previously) feed types, respectively. The four treatments were (1) standard feed offered ad libitum (AL) throughout 24 h; (2) as per AL, with preferred feed replacing standard feed between 2400 and 0600 h (AL + P); (3) standard feed offered at a restricted rate, with quantity varying between each feeding period (20:10:30:60%, respectively) as a proportion of the (previously) measured daily ad libitum intake (VA); (4) as per VA, with preferred feed replacing standard feed between 2400 and 0600 h (VA + P). Eight non-lactating dairy cows were used in a 4 × 4 Latin square design. During each experimental period, treatment cows were fed for 7 days, including 3 days habituation and 4 days data collection. Total daily intake was approximately 8% greater (P < 0.001) for the AL and AL + P treatments (23.1 and 22.9 kg DM/cow) as compared with the VA and VA + P treatments (21.6 and 20.9 kg DM/cow). The AL + P and VA treatments had 21% and 90% greater (P < 0.001) dry matter intake (DMI) between 2400 and 0600 h, respectively, compared with the AL treatment. In contrast, the VA + P treatment had similar DMI to the VA treatment. Our experiment shows ability to increase cow feeding activity at night by varying feed type and quantity, though it is possible that a penalty to total DMI may occur using VA. Further research is required to determine if the implementation of variable feed allocation on pasture-based AMS farms is likely to improve milking robot utilisation by increasing cow feeding activity at night.

Effects of feeding Lespedeza cuneata pellets with Medicago sativa hay to sheep: Nutritional impact, characterization and degradation of condensed tannin during digestion

Sustainable ruminant livestock production could benefit from feedstuffs containing condensed tannin (CT) if they maintained or improved livestock health and productivity while reducing the excretion of urinary nitrogen (N), which can be readily lost to the environment. Such feedstuffs would be most useful if they were easy and inexpensive to grow and could be field dried and pelletized for ease of transport and storage. One feedstuff that may meet these criteria is pelleted sericea lespedeza (SL; Lespedeza cuneata). Therefore, a 4 × 4 Latin square trial was conducted with four mature male sheep fed four proportions of pelleted SL with alfalfa (Medicago sativa) hay cubes, to determine effects on digestion and N excretion, and the fate of the CT during digestion. Pelleted SL contained (g/kg dry matter; DM) 182 CT, 23.3N, 341 aNDF, 227 ADF, 87 ADL and 55 ash, while the cubed alfalfa hay contained (g/kg DM) 28.5N, 381 aNDF, 284 ADF, 78 ADL and 137 ash. The SL pellets were consumed readily, but increasing their proportion in the ration DM from 0 to 0.4 linearly decreased apparent digestibility of DM from 59.7 to 49.9% and N from 74.7 to 53.4%, with associated reductions in urinary N excretion. Evaluation with 1H-13C heteronuclear single quantum coherence nuclear magnetic resonance (HSQC NMR) spectroscopy detected trace amounts of intact CT in sheep feces and analysis of the feces from the 0.4 lespedeza pellet ration using the HCl-butanol-acetone-iron assay indicated that 96% of the CT had been modified into non-proanthocyanidin components. Fiber analysis conducted with and without sulfite indicated an accumulation of sulfite-resistant CT-protein complexes in feces which likely contributed to the reduction in digestibility of fiber and N. This study has shown that SL pellets reduced urinary N excretion and diverted feed N to feces, but their inclusion in the diet reduced the apparent digestibility of DM and N. Complexes of CT, protein and fiber were the main contributor to the poor digestibility of aNDF and ADF in diets containing SL pellets. Findings presented here suggest a potential negative effect of these SL pellets on long-term sheep productivity in contrast to short-term productivity improvements due to the ability of the SL pellets to reduce gastrointestinal parasite populations.

Effect of wheat adaptation strategies on rumen parameters and dry matter intake of late lactation dairy cows

The effects of a major dietary change on ruminal fluid pH, volatile fatty acid (VFA), lactate and ammonia concentrations, dry matter intake (DMI) and milk yield were measured in 32 dairy cows in late lactation. All cows were initially fed 100% lucerne hay cubes and were then gradually introduced to a diet with wheat comprising 40% of total dry matter (DM) and lucerne hay cubes, the remainder. Wheat was gradually substituted for lucerne via one of four strategies, (1) in six small increments (each 6.7% of total DM) over 6 days; (2) in six small increments (each 6.7% of total DM) over 11 days; (3) in three large increments (each 13.3% of total DM) over 6 days; or (4) in three large increments (each 13.3% of total DM) over 11 days. The introduction of wheat in six small increments resulted in a lower daily minimum ruminal fluid pH (pH 5.95) when compared with using three large increments (pH 6.05). Despite this difference none of the treatments exhibited a ruminal fluid pH that would have compromised ruminal function, nor were there differences in DMI (19.7 kg DM/cow.day) or milk yield (16.0 kg/cow.day). Additionally, there were no differences between ruminal fluid VFA, lactate or ammonia concentrations. It is speculated that the properties of the lucerne cubes, including a high buffering capacity, helped the ruminal contents resist the pronounced declines in pH often seen with the fermentation of large amounts of wheat. Under the conditions of this experiment the wheat adaptation strategies used did not lead to any critical differences in rumen parameters. These results suggest that changes to rumen function are driven not only by the characteristics of the concentrate being introduced but also by those of the forage.

Short communication: The diurnal intake and behavior of dairy cows when access to a feed of consistent nutritive value is restricted

The diurnal variation in pasture nutritive value adds a confounding factor to studies elucidating the effect of time of day on behavior. Our work separates the effect of time of day on both feeding and lying patterns for cows outdoors to enable the alignment of feeding behavior with feed management. We determined the diurnal intake patterns and behavior of dairy cows when the nutritive value of feed remained constant throughout 24 h in an outdoor environment, and when feed access was restricted. Nine nonlactating Holstein-Friesian cows (live weight 626 ± 53 kg, age 96 ± 33 mo; mean ± SD) were split into 3 groups of 3 and offered lucerne hay cubes (cube volume 32 mm3) ad libitum according to 3 treatments: full access (FA, feed access 24 h), day access (DA, feed access between 0600 and 1800 h), and night access (NA, feed access between 1800 and 0600 h). Treatments were applied to individual cows in a crossover design with 7-d periods. During the last 4 d of each period, data were collected on feed intake, as well as feeding and lying behaviors. Total daily intake was greater for cows on the FA treatment (3.5% of BW) compared with the DA and NA treatments at 3.1 and 2.9% of BW, respectively. The cows with FA consumed 69% of their total intake during the day (0600-1800 h), with the greatest intake (39%) occurring during 1200 to 1800 h and only 12% of intake occurring during 2400 to 0600 h. Cows with DA consumed 56% of feed during 0600 to 1200 h and 44% during 1200 to 1800 h. In contrast, NA cows consumed more feed (74%) during the first 6 h period (1800-2400 h), thus maximizing lying time between 2400 and 0600 h. The time spent lying throughout daylight periods varied between treatments; however, total daily lying time was similar across the 3 treatments. This experiment shows the feeding and lying behaviors of cows when feed quality remains constant throughout 24 h, which will assist the formulation of variable feed allocation strategies for future testing in both robotic and conventional milking systems. Varying the quantity of feed offered throughout 24 h may benefit robot utilization at night in automatic milking systems through increased feeding activity, and as we observed, is likely to have little effect on lying time or DMI, with cows readily adapting to changes in feed management. Conversely, aligning feed on offer with preferred feeding time in conventional milking systems may increase the intake of high quality pasture.

Preference by horses for bedding pellets made from switchgrass (Panicum virgatum) straw

<h2>ABSTRACT</h2> The bedding system used for stalled horses can affect their health. This study examined the saponin concentration in switchgrass (<i>Panicum virgatum</i>) straw, and bedding pellets made from switchgrass straw. Further, this study determined the palatability of bedding pellets made from switchgrass straw and pine wood to horses. Saponins have been implicated in photosensitization in livestock, including horses. The average concentrations of the saponins dichotomin and protodioscin in switchgrass bales were 0.37 and 0.19 μg/g, respectively. The concentration of dichotomin decreased 38% from bales to the final pellets from a combination of environmental factors and dilution with other plant material. In the initial 8-d trial, horses were tested to determine their preference for (1) switchgrass straw bedding pellets, (2) Omolene horse feed, (3) alfalfa hay cubes, and (4) Equine Pine Pellet bedding. In a second 4-d trial, barley straw was substituted for Omolene. On each test day, the fasted horses were given 30 min to consume the feeds and bedding pellets. Horses preferred both alfalfa cubes and Omolene (consumption ≥99% of offered) and rejected (<i>P</i> < 0.05) both switchgrass bedding pellets and pine bedding pellets (≤0.6% of offered). When barley straw was substituted for Omolene in the second 4-d period, horses consumed a small amount of straw (6% of offered), and again horses rejected (<i>P</i> < 0.05; ≤0.2% of offered) both switchgrass and pine bedding pellets. This study suggests that the risk of intoxication from horses ingesting bedding pellets made with switchgrass straw is very low.

Effects of alfalfa hay cubes versus timothy hay cubes on measures of whole-body protein metabolism in mature horses

Effects of alfalfa hay cubes versus timothy hay cubes on measures of whole-body protein metabolism in mature horses

Effects of an intravenous replenishment of salivary components on feed intake in large-bodied goats fed on crushed alfalfa hay cubes

Effects of an intravenous replenishment of salivary components on feed intake in large-bodied goats fed on crushed alfalfa hay cubes

Nutritional values and antioxidative activities of whole peanuts and peanut skins for ruminant feeds.

This study was conducted to investigate the nutritive values of two peanut by-products, nonstandardized whole peanuts and peanut skins, along with their effects on microbial growth and fermentation in the rumen, their roughage values, and their antioxidative activities by a digestion trial using four goats. The experimental rations were alfalfa haycube (basal ration), 85% alfalfa with 15% whole peanuts, and 70% alfalfa with 15% whole peanuts and 15% peanut skins. The ether extracts and crude protein in whole peanuts were 47% and 27% on a dry matter basis (DM) both with over 90% of digestibilities, resulting in total digestive nutrients (TDN) of 140%. Peanut skins also had a high energy value with 91% of TDN. Ruminal concentrations of total volatile fatty acids (VFA) and acetic acid decreased in the rations containing the peanut by-products, but the NDF digestibility and ruminal microbial protein estimated from urinary purines was not altered by feeding the peanut by-products. Plasma oxidative stress maker, malondialdehyde, tended to be lower when peanut skins were supplemented. Whole peanuts and peanut skins could be used as high-energy and high-protein diets for ruminants, and peanut skins would be expected as a feed having antioxidant functions.

Apple pomace silage ethanol intake and its effect on sheep

Two experiments were undertaken to investigate the feeding effect of alcoholic apple pomace silages (APSs) on performance traits, ruminal pH and blood variables in sheep. In experiment 1, four ewes were fed alfalfa hay cube and either APS (ethanol content was 33.4 g /kg DM) or concentrate (control) at a ratio of 30:70 of TDN requirement for maintenance and daily 100g gain in a 2×2 crossover design over two 35-day periods. Total body weight gain was higher in control treatment. No significant treatment effect was observed for TDN intake and ruminal pH. Plasma concentrations of ethanol, lactate and ?-hydroxybutyrate (BHBA) were increased after feeding APS. Plasma insulin, glucose, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) were not significantly differ between the treatments. The area upper or under curves (AUCs)of plasma ethanol and BHBA were greater and lactate was tended to greater in APS treatment. In experiment 2, low and high ethanol contained APSs (L-APS, 44.1g and H-APS, 66.9 g of ethanol/kg DM) were compared in the same design (Experiment 1). No significant treatment effect was observed for body weight gain and TDN intake. Pre-feeding ruminal pH was lower in L-APS treatment. Insulin concentration was slightly higher in L-APS treatment. However, no significant treatment effect was detected for other variables. According to the consistent increase in plasma ethanol, lactate and BHBA, and the plasma AUCs response of ethanol, lactate and BHBA after feeding of alcoholic-fermented APSs, it would be concluded that APS ethanol consumption affect the post prandial blood metabolism as well as influenced the plasma lactate and BHBA concentrations in the blood.DOI: http://dx.doi.org/10.3329/bjas.v43i3.21655 Bang. J. Anim. Sci. 2014. 43 (3): 224-231

Feed intake, digestibility, nitrogen utilization, ruminal condition and blood metabolites in wethers fed ground bamboo pellets cultured with white‐rot fungus (Ceriporiopsis subvermispora) and mixed with soybean curd residue and soy sauce cake

Three types of bamboo pellets as a ruminant feed: P1 (ground bamboo (GB) cultured with the fungus Ceriporiopsis subvermispora (CGB) : soybean curd residue (T) : soy sauce cake (S) in a 5:4:1 ratio on a dry matter (DM) basis); P2 (GB : T : S = 5:4:1 on a DM basis); and P3 (CGB : T : S = 5.5:0.8:3.7 on a DM basis) were prepared. Four wethers were assigned in a 4 × 4 Latin square design experiment to evaluate the applicability of the bamboo pellets. The experimental treatments were C (control): fed alfalfa hay cubes (AC) only, and T1, T2 and T3: fed P1, P2, and P3 with AC by 1:1 on a DM basis, respectively. The digestibility of the DM, organic matter and acid detergent fiber of P1 were significantly higher than those of P2 and P3 (P < 0.05). The total digestible nutrient (TDN) contents of AC, P1, P2 and P3 were 56.5%, 60.2%, 53.2% and 47.0%, respectively. No significant differences in nitrogen retention or ruminal pH and NH₃ were observed among the treatment groups. The results indicate that bamboo pellets cultured with C. subvermispora and mainly mixed with soybean curd residue improved nutritional quality of ground bamboo because of its high digestibility and TDN content.

Energy metabolism by splanchnic tissues of mature sheep fed varying levels of lucerne hay cubes

The objective of this study was to determine the pattern of energy metabolites net flux across the portal-drained viscera (PDV) and total splanchnic tissues (TSP) in mature sheep fed varying levels of lucerne hay cubes. Four Suffolk mature sheep (61.4 ± 3.6 kg BW) surgically fitted with multi-catheters were fed four levels of dry matter intake (DMI) of lucerne hay cubes ranging from 0.4- to 1.6-fold the metabolizable energy (ME) requirements for maintenance. Six sets of blood samples were simultaneously collected from arterial and venous catheters at 30-min intervals. With increasing DMI, apparent total tract digestibility increased linearly and quadratically for dry matter (P < 0.05), quadratically (P < 0.05) with a linear tendency (P < 0.1) for organic matter and tended to increase quadratically (P < 0.1) for NDF. PDV release of volatile fatty acids (VFA) and β-hydroxybutyric acid was relatively low at 0.4 M and then linearly increased (P < 0.05) with increasing DMI. Net PDV flux of non-esterified fatty acids showed curvilinear decrease from 0.4 to 1.2 M and then increased at 1.6 M. The respective proportions of each VFA appearing in the portal blood differed (P < 0.05) with DMI and this difference was more obvious from 0.4 to 0.8 M than from 0.8 to 1.6 M. Heat production, as a percentage of ME intake (MEI), decreased linearly (P < 0.05) with increasing DMI accounting for 37%, 21%, 16% and 13% for PDV and 62%, 49%, 33% and 27% for TSP at 0.4, 0.8, 1.2 and 1.6 M, respectively. As a proportion of MEI, total energy recovery including heat production, decreased linearly with increasing DMI (P < 0.05) accounting for 113%, 83%, 62% and 57% for PDV and 140%, 129%, 86% and 83% for TSP at 0.4, 0.8, 1.2 and 1.6 M, respectively. Regression analysis revealed a linear response between MEI (MJ/day per kg BW) and total energy release (MJ/day per kg BW) across the PDV and TSP, respectively. However, respective contributions of energy metabolites to net energy release across the PDV and TSP were highly variable among treatments and did not follow the same pattern of changes in DMI.

Effects of forage intake level on nitrogen net flux by portal-drained viscera of mature sheep with abomasal infusion of an amino acid mixture

This study aimed to investigate the pattern of nitrogen (N) metabolites flux across the portal-drained viscera (PDV) of mature sheep over a wide range of forage intake, and to determine the effect of dry matter intake (DMI) on the PDV recovery of an abomasally infused amino acids (AA) mixture. Four Suffolk mature sheep (61.4 ± 3.6 kg BW) surgically fitted with abomasal cannulae and multi-catheters were fed four levels of DMI of lucerne hay cubes ranging from 0.4 to 1.6 fold the metabolizable energy requirements for maintenance. Each period lasted for 17 days: 7 days for diet adaptation, 5 days for measurement of N balance and N metabolites flux under basal pre-infusion conditions (basal phase) and 5 days for determining the recovery of the infused AA (584 mmol/day) across the PDV (infusion phase). Six sets of blood samples were collected on the last day of both basal and infusion phases. Increasing DMI increased portal release of AA and enhanced N retention. At 0.4 M and as a proportion of digested N, there was a marked drop in total AA-N release accompanied by greater ammonia-N release and urea-N uptake across the PDV. The incremental recovery ratio of infused AA across the PDV was altered with increasing DMI accounting for 0.88, 1.12, 1.23 and 1.31 at 0.4, 0.8, 1.2 and 1.6 M, respectively. In addition, across the individual AA, the net portal recovery ratio of infused methionine and valine increased linearly (P < 0.05) while that of phenylalanine, branched-chain AA and total essential AA tended to increase linearly (P < 0.10) with increasing DMI. These results indicated that DMI affects the net portal recovery of AA available in the small intestine of mature sheep.

The Main Suppressing Factors of Dry Forage Intake in Large-type Goats.

In large-type goats that were fed on dry forage twice daily, dry forage intake was markedly suppressed after 40 min of feeding had elapsed. The objective of this study was to determine whether or not marked decreases in dry forage intake after 40 min of feeding are mainly caused by the two factors, that is, ruminal distension and increased plasma osmolality induced thirst produced by dry forage feeding. Six large-type male esophageal- and ruminal-fistulated goats (crossbred Japanese Saanen/Nubian, aged 2 to 6 years, weighing 85.1±4.89 kg) were used in two experiments. The animals were fed ad libitum a diet of roughly crushed alfalfa hay cubes for 2 h from 10:00 to 12:00 am during two experiments. Water was withheld during feeding in both experiments but was available for a period of 30 min after completion of the 2 h feeding period. In experiment 1, saliva lost via the esophageal fistula was replenished by an intraruminal infusion of artificial parotid saliva (RIAPS) in sham feeding conditions (SFC) control, and the treatment was maintained under normal feeding conditions (NFC). In experiment 2, a RIAPS and non-insertion of a balloon (RIAPS-NB) control was conducted in the same manner as the SFC control of experiment 1. The intraruminal infusion of hypertonic solution and insertion of a balloon (RIHS-IB) treatment was carried out simultaneously to reproduce the effects of changing salt content and ruminal distension due to feed entering the rumen. The results of experiment 1 showed that due to the effects of multiple dry forage suppressing factors when feed boluses entered the rumen, eating rates in the NFC treatment decreased (p<0.05) after 40 min of feeding and cumulative dry forage intake for the 2 h feeding period reduced to 43.8% of the SFC control (p<0.01). The results of experiment 2 indicated that due to the two suppressing factors of ruminal distension and increased plasma osmolality induced thirst, eating rates in the RIHS-IB treatment were, as observed under NFC, reduced (p<0.05) and cumulative dry forage intake for the 2 h feeding period decreased to 34.0% of the RIAPS-NB control (p<0.01). The combined effects of ruminal distension and increased plasma osmolality accounted for 77.5% of the suppression of dry forage intake 40 min after the start of dry forage feeding. The results indicate that ruminal distension and increased plasma osmolality induced thirst are the main factors in the suppression of dry forage intake in large-type goats.

Variation in residual feed intake in Holstein-Friesian dairy heifers in southern Australia

Feed conversion efficiency of dairy cattle is an important component of the profitability of dairying, given that the cost of feed accounts for much of total farm expenses. Residual feed intake (RFI) is a useful measure of feed conversion efficiency, as it can be used to compare individuals with the same or differing levels of production during the period of measurement. If genetic variation exists in RFI among dairy cattle, selection for lower RFI could improve profitability. In this experiment, RFI was defined as the difference between an animal's actual feed intake and its expected feed intake, which was determined by regression of dry matter (DM) intake against mean body weight (BW) and growth rate. Nine hundred and three Holstein-Friesian heifer calves, aged between 5 and 7 mo, were measured for RFI in 3 cohorts of approximately 300 animals. Calves were housed under feedlot style conditions in groups of 15 to 20 for 85 to 95 d and had ad libitum access to a cubed alfalfa hay. Intakes of individual animals were recorded via an electronic feed recording system and BW gain was determined by weighing animals once or twice weekly, over a period of 60 to 70 d. Calves had DM intake (mean ± SD) of 8.3±1.37kg of DM/d over the measurement period with BW gains of 1.1±0.17kg/d. In terms of converting feed energy for maintenance and growth, the 10% most efficient calves (lowest RFI) ate 1.7kg of DM less each day than the 10% least efficient calves (highest RFI) for the same rate of growth. Low-RFI heifers also had a significantly lower rate of intake (g/min) than high-RFI heifers. The heritability estimate of RFI (mean ± SE) was 0.27 (±0.12). These results indicate that substantial genetic variation in RFI exists, and that the magnitude of this variation is large enough to enable this trait to be considered as a candidate trait for future dairy breeding goals. A primary focus of future research should be to ensure that calves that are efficient at converting feed energy for maintenance and growth also become efficient at converting feed energy to milk. Future research will also be necessary to identify the consequences of selection for RFI on other traits (especially fertility and other fitness traits) and if any interactions exist between RFI and feeding level.

Plasma Osmolality Controls Dry Forage Intake in Large-type Goats

In large-type goats that were fed on dry forage twice daily, dry forage intake was markedly suppressed after 40 min of feeding had elapsed. The objective of this study was to clarify whether or not increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding suppress dry forage intake. Eight large-type male esophageal- and ruminal-fistulated goats (crossbred Japanese Saanen/Nubian, aged 3 to 6 years, weighing 72.3±2.74 kg) were used in two experiments conducted under sham feeding conditions. The animals were fed ad libitum a diet of roughly crushed alfalfa hay cubes for 2 h from 10:00 to 12:00 h during two experiments. Water was withheld during feeding in both experiments but was available for a period of 30 min after completion of the 2 h feeding period. In experiment 1, an intraruminal infusion of artificial parotid saliva (RIAPS) in the control replenished saliva lost via the esophageal fistula and an intraruminal infusion of hypertonic solution (RIHS) in the treatment was carried out in order to reproduce the effects of changing salt content due to feed entering the rumen. In experiment 2, the RIHS control was conducted in the same manner as the RIHS treatment of experiment 1. The treatment group consisted of RIHS-with an intravenous infusion of artificial mixed saliva (VIAMS) treatment that was carried out for 3 h to prevent increases in plasma osmolality during feeding. The results of the RIHS treatment in experiment 1 showed that ruminal fluid osmolality increased and then an increase in plasma osmolality was observed. This resulted in the production of thirst sensations and the reduction of cumulative dry forage intake to 43.3% (p<0.05) of the RIAPS control. The results of the RIHS-VIAMS treatment in experiment 2 indicated that ruminal fluid osmolality was the same as the RIHS control but plasma osmolality significantly decreased, and thirst level was markedly reduced. This caused a significant increase of 31.4% (p<0.05) in cumulative dry forage intake in the RIHS-VIAMS treatment compared to the RIHS control. These results indicate that increases in ruminal fluid osmolality during dry forage feeding indirectly suppresses dry forage intake by causing an increase in plasma osmolality and subsequently inducing thirst sensations. The results of the present study suggest that marked decreases in dry forage intake after 40 min of feeding are caused by increases in plasma osmolality and subsequent thirst sensations produced by dry forage feeding. (Key Words : Ruminal Fluid Osmolality, Plasma Osmolality, Thirst Level, Dry Forage Intake, Large-type Goats)

Effects of Feed Form on Growth and Stomach Ulcers in Yearling Horses

Fourteen yearling Standardbreds, seven fillies and seven colts of similar weight, sex, age, and growth potential, with an average age of 8 months, and an average initial weight of 294 kg, were used to compare differences in ADG and G/F when fed a complete cubed diet (C), or a diet in which the alfalfa hay cubes and oats were fed separately (HG). The forage in both the plain hay cubes and the complete cubes was 80% alfalfa and 20% endophyte-free tall fescue. Diets were fed for 75 days, during which horses were fed no additional feeds, and had free-choice access to water, mineral blocks, and exercise. Horses were weighed on an electronic platform scale before the study and weekly for its duration. Upper gastrointestinal tract endoscopies were performed on all horses at the start and end of the study. Seven horses were randomly assigned to each diet and fed twice daily at 7:00 and 19:00 at a rate of 1.5% body weight as-fed. Horses were housed and fed in individual pens of 500 square feet with identical feeders. At each feeding, leftover feed was recovered and weighed to determine consumption. Feed samples were continuously collected and composited. Fecal samples were collected on days 71-75. Feces were composited and stored at -4 degrees Celsius. Collections were oven-dried at 60 degrees Celsius and samples were sent to a laboratory (Equi-analytical labs, Ithaca, NY) for analysis of dry matter (DM), crude protein (CP) and acid insoluble ash (AIA) using AOAC methods8. Apparent digestibility was calculated using the equation: 100 x (1-(% AIA in feed / % AIA in feces) x (% nutrient in feces / % nutrient in feed))9. Differences in digestibility, ADG, and G/F between diets were determined using T tests.

Effect of Feed Processing Method on Average Daily Gain and Gastric Ulcer Development in Weanling Horses

The present study evaluated the effects of two different methods of feed processing on growth and gastric ulceration in 16 weanling Standardbred horses. The two diets were composed of identical ingredients that were processed differently and fed at a rate of 3% body weight per day. The hay and grain diet (diet HG) consisted of 50% alfalfa hay cubes and 50% commercial texturized grain mix fed as is, without any further processing, with the cubes and grain fed in separate containers. The complete pelleted diet (diet CP) consisted of the same proportion of hay cubes and grain mix, which was ground, pelleted, and fed in a single container. The horses were divided into two groups and the study was divided into three periods of 30 days each. During period 1, all 16 horses consumed only free choice alfalfa hay (diet H). Group 1 was given diet CP during period 2 and diet HG during period 3. Group 2 was given diet HG during period 2 and diet CP during period 3. The horses were endoscopically examined for the baseline number and severity of stomach ulcers at the end of period 1, then again at the end of each treatment diet feeding period. Horses on diet CP in periods 2 and 3 had greater ulcer numbers ( P = .0135) than diet HG. However, there was no significant difference ( P = .30) in ulcer numbers when making a direct comparison between diets CP and HG. Despite the gastric ulceration found in horses on diet CP, the average daily gain was significantly greater ( P = .016) for diet CP than for diet HG. Both diets containing grain were observed to cause gastric ulceration.