Digestibility Of Lambs Research Articles

Effect of a Yeast Culture on Nitrogen Balance and Digestion in Lambs Fed Early and Mature Orchard Grass

Hernández, R., González, S.S., Pinos-Rodríguez, J.M., Ortega, M.E., Hernández, A., Bueno, G. and Cobos, M. 2009. Effect of a yeast culture on nitrogen balance and digestion in lambs fed early and mature orchard grass. J. Appl. Anim. Res., 35: 53–56. To evaluate the effect of feeding a yeast culture (0 or 5 g/d per sheep) on digestion and N balance in lambs fed orchard grass hay cut at 5 or 16-wk of re-growth, 4 male Criollo lambs (45 ± 4 kg) fitted with ruminal cannulae in a 4x4 Latin square with a factorial 2x2 arrangement of treatments were used. Addition of a yeast culture did not affect (P>0.05) intake, rumen pH and ammonia N, N balance and total tract digestion of nutrients. Ruminal total protozoa changed only according to orchard grass maturity (P<0.05); however, treatments did not affect total and cellulolytic bacteria, rumen pH and rumen ammonia N concentration. It is concluded that addition of a yeast culture to lambs fed early and mature orchard grass did alter ruminal protozoa without affecting feed intake, total tract digestion and N balance.

Effects of supplemental ruminally degradable protein versus increasing amounts of supplemental ruminally undegradable protein on site and extent of digestion and ruminal characteristics in lambs fed low-quality forage1

Four ruminally and duodenally cannulated Suffolk wether lambs (34.5 +/- 2 kg initial BW) were used in a 4 x 4 Latin square designed experiment to compare effects of supplemental ruminally degradable protein (RDP) vs. increasing amounts of supplemental ruminally undegradable protein (RUP) on ruminal characteristics and site and extent of digestion in lambs. Lambs were fed a basal diet of crested wheatgrass hay (4.2% CP) for ad libitum consumption, plus 1 of 4 protein supplements: isolated soy protein (RDP source) fed to meet estimated RDP requirements assuming a microbial efficiency of 11% of TDN (CON) or corn gluten meal (RUP source) fed at 50, 100, or 150% of the supplemental N provided by CON (C50, C100, and C150, respectively). Neither NDF nor ADF intake was affected (P >/= 0.18) by protein degradability, but they increased or tended to increase (P </= 0.07) with increasing level of RUP. Total OM and N intakes were similar (P >/= 0.26) for CON and C100, but increased (P </= 0.01) as level of RUP increased. True ruminal OM and ruminal digestibilities of NDF and ADF were not affected (P >/= 0.33) by protein degradability. However, true ruminal N digestibility was greater (P = 0.03) for CON compared with C100. Ruminal ammonia concentrations were greater (P = 0.002) for CON compared with C100 lambs, and increased (P = 0.001) with increasing RUP. Microbial N flows were not affected (P >/= 0.12) by protein degradability or increasing RUP. Likewise, neither ruminal urease activity (P >/= 0.11) nor microbial efficiency (P >/= 0.50) were affected by protein degradability or level of RUP. Total tract OM, NDF, and ADF digestibility was greater (P </= 0.05) for C100 compared with CON. Likewise, total tract N digestibility was greater (P = 0.03) for C100 than for CON, and increased linearly (P = 0.001) with increasing RUP. Lambs fed C100 consumed approximately 69% less supplemental RDP (31% less total RDP) than CON, but were able to maintain forage intake and digestion. This lack of response in forage intake would suggest that lambs supplemented with RUP were recycling sufficient N to compensate for an apparent RDP deficiency. Although ruminal degradability of protein has little effect on forage intake or ruminal digestion of nutrients, there is potential to enhance total tract digestion of nutrients by decreasing the ruminal degradability of supplemental protein.

Efficacy of exogenous cellulase on digestibility in lambs and growth of dairy calves

Two experiments were carried out to investigate the efficacy of direct feeding a fibrolytic enzyme on lamb digestibility and on the performance of growing milk-type calves. In the first experiment, 10 lambs were divided into two groups, cellulase treated and a control, and placed in metabolic crates for two periods of 12 days each in a switchover design. For the feeding trial, 16 male and 15 female Friesian calves were utilized in a repeated measure complete randomized design. Each of the two sexes was allocated into one of two groups and fed the same ration, either treated or not with exogenous cellulase. All animals were treated individually. A total mixed ration was offered ad libitum to males and in a restricted feeding regime to females. The digestibility study showed that treated lambs had higher ( P<0.05) digestibilities for dry matter, organic matter, crude fiber, neutral and acid detergent fiber. Also, they retained more ( P<0.05) nitrogen in their bodies than the control lambs. Treated males had higher ( P<0.05) gain than control ones. No differences were reported between female groups. No differences were observed in feed intake, average feed intake and daily feed intake in both sexes. Enzyme-treated males showed improved ( P<0.05) feeding efficiency compared to no cellulases while no differences were obtained with females. Financial analysis showed no differences in feed or total costs while gross and total income were higher for treated animals than untreated ones. These results demonstrated the benefits of using fibrolytic enzyme additives to improve total tract digestibility and enhance growth performance of milk calves and replacement heifers.

Supplementation of Acacia cyanophylla Lindl. foliage-based diets with barley or shrubs from arid areas ( Opuntia ficus-indica f. inermis and Atriplex nummularia L.) on growth and digestibility in lambs

Twenty-eight Barbarine yearling lambs (4 months of age, average live weight 22.0±2.3 kg) given freshly cut Acacia cyanophylla Lindl. (acacia) foliage ad libitum supplemented with either 0.3 kg barley (B), 4.5 kg freshly cut pads of Opuntia ficus-indica f. inermis (cactus) (C), 0.3 kg barley and 1.4 kg freshly cut Atriplex nummularia L. foliage (atriplex) (B+A) or 4.5 kg cactus and 1.4 kg atriplex (C+A) were used in an 80-day study comprising growth, digestibility and N balance trials. The sheep were blocked by weight and within each block randomly allocated to four treatments giving seven animals per treatment. Condensed tannins (CT) content was high in acacia. Great amount of total oxalates was found in cactus (131 g/kg dry matter (DM)). Sheep consumed significantly less acacia when supplemented with cactus either alone (C) or with atriplex (C+A) as compared with (B) and (B+A) diets (28.7, 26.3, 36.6 and 38.3 g DM/kg W 0.75, respectively). The amount of drinking water was reduced in sheep given cactus as compared with those receiving barley and was increased with atriplex supply. Supplementing sheep with cactus alone substantially reduced organic matter (OM), crude protein (CP) and cell wall digestibility of the diet as compared with barley diet (B). These negative effects were reduced when cactus was fed in combination with atriplex. Nitrogen retention (g per day) with C-diet was proportionately about 0.61 lower than with (C+A)-diet and 0.32 lower with (C+A)-diet than with (B+A)-diet. Replacing barley by cactus had no effect upon the urinary excretion of allantoin, and thus on estimated microbial N supply to the small intestine. Atriplex supplied either with barley or cactus improved the efficiency of microbial protein synthesis. Replacing barley with cactus significantly reduced daily gains. Sheep on (B+A)-diet gained more (54 g per day) than those on the other dietary treatments. It was concluded that acacia may be utilised in sheep feeding provided that an adequate supply of both energy and nitrogen is made. Highest positive responses were obtained when barley was used as supplement of acacia with or without atriplex. Cactus alone was not able to replace barley as supplement to acacia. It should be offered in combination with a nitrogen-rich supplement, such as atriplex, to ensure normal microflora activity in the rumen. A diet of acacia supplemented with cactus and atriplex could be a cost-effective solution to nourish sheep during dry seasons.

The effects of sequence of feed allocation within the day on microbial protein production and diet digestibility in lambs fed barley or sugar beet based diets

Feeding lambs diets formulated to be synchronous in terms of hourly energy and protein supply to the rumen has been reported to improve the efficiency of energy utilisation (Richardsonet al.1999). In a previous study Sinclairet al.(1995) reported that the efficiency of microbial protein production was improved when animals were fed a synchronous diet. The objectives of the present study were to investigate whether the changes in metabolism reported by Richardsonet al.(1999) may be related to rumen microbial protein production and diet digestibility.

Effects of ruminal inoculations with tannin-tolerant bacteria on fibre and nitrogen digestibility of lambs fed a high condensed tannin diet

The goal of this study was to evaluate the effects of dosing unadapted lambs with tannin-tolerant bacteria to improve the digestibility of a high condensed tannin (CT) diet. During the initial phase (metabolism study), a diet containing 30% peanut skins was fed to two groups of Suffolk × Finn-Dorset ram lambs that were about three months old and weighed an average of 24.2 ± 1.4 kg. All animals received 150 ml of a culture (A 600 of 1.0) of a Gram positive rod (a close relative of Eubacterium cellulosolvens) that was able to tolerate 0.5 g/l of purified CT from Desmodium ovalifolium. The control group (7 animals) was inoculated with autoclaved bacteria. The treatment group (6 animals) was inoculated with actively growing bacteria. Inoculations were made daily during a three-week period. Dry matter intake (DMI) was 55.4 and 64.9 g/kg 0.75/day for the control and treatment group, respectively, ( P = 0.13). Digestibility of DM, crude protein (CP) and neutral detergent fibre (NDF) was similar between treatments. Crude protein intake ( P = 0.10) and CP retention ( P = 0.07) were higher for animals inoculated with live bacteria. The CP retention/CP intake ratio was also higher for animals inoculated with the live bacteria ( P = 0.07). To investigate carry-over effects on animal performance due to the bacterial inoculations after the metabolism study, the animals were kept in metabolism cages, but they received no supplemental bacteria. During a subsequent two-week period, the animals continued to receive the high CT diet. Dry matter and CP intake, as well as the feed : gain ratio, were similar between the groups of animals. Finally, for a second two-week period, the animals were fed a low CT (normal) diet without peanut skins. Dry matter intake was 92.9 and 88.6 g/kg 0.75/day for the control and treatment groups, respectively ( P = 0.14). Crude protein intake and feed : gain ratio were similar between the two groups of animals.

Effects of barley cultivar on energy and nitrogen metabolism of lambs

The aim of this research was to compare energy values, nitrogen metabolism and diet digestibility of four barley (Hordeum vulgare L.) cultivars grown in two different years, to identify the most important factors affecting variation. Six wether lambs (39.4 ± 1.6 kg) were assigned within period in a randomized complete block design to barley cultivar (1990 Camelot, 1990 Cougbar, 1990 Steptoe, 1991 Boyer, 1991 Camelot and 1991 Steptoe) and consumed a diet of 83% barley, 10% alfalfa pellets and 7% supplement on a DM basis. During each 14-d period, feed, orts, fecal and urine samples were collected during the last 7 d and methane emissions were quantified. Digestibility of NDF polymeric monosaccharides was lower (P &lt; 0.10) for weathers fed 1990 Steptoe than all cultivars other than 1991 Boyer and was positively correlated to methane production (r = 0.52). Barley DE was not different among cultivars but, because methane production was greater (P &lt; 0.10) for lambs fed 1991 Boyer (38 L d−1) than for those fed 1990 Steptoe (21 L d−1) and 1990 Camelot (26 L d−1), barley ME content of 1991 Boyer (12.3 MJ kg−1 OM) was lower (P &lt; 0.10) than for 1990 Steptoe (13.4 MJ kg−1 OM). Nitrogen digestibility in lambs fed Camelot grown both years was greater (P &lt; 0.05) than for most cultivars. Absorbed nitrogen was greatest (P &lt; 0.10) in lambs fed 1991 Camelot and nitrogen retention (g d−1) tended to be greater than 1990 Cougbar (P = 0.14) and 1990 Camelot (P = 0.16) fed lambs. Cougbar, Boyer and 1991 Steptoe had lower feeding quality for ruminants because of lower energy and/or nitrogen metabolism, while both years of Camelot and 1990 Steptoe had greater ME values. Methane production, digestibility of NDF polymeric monosaccharides and nitrogen metabolism were major factors contributing to variability among barley cultivars within and between years. Key words: Barley, lambs, methane, metabolizable energy

Performance of lambs fed either hay or silage supplemented with canola or fish meals

Forty-eight lambs (29.0 ± 4.7 kg BW) were used to study the effects of protein supplementation of forages on performance and diet digestibility. Lambs were fed grass hay or silage ad libitum plus a daily supplement of either: C, a control supplement supplying 1.2 g kg−1 BW of dry molasses and 0.6 g kg−1 BW of minerals, vitamins and lasalocid; CM, control supplement + 5.48 g kg−1 BW of canola meal; or FM, control supplement + 3 g kg−1 BW of fish meal. Apparent digestibility of all dietary components was higher in lambs fed silage than in those fed hay (P &lt; 0.04). Addition of CM or FM improved apparent digestibility of energy and crude protein (CP) of lambs fed hay (P &lt; 0.02) and CP digestibility of lambs fed silage (P &lt; 0.01). Apparent digestibility of CP was higher in lambs fed FM than in those fed CM with either hay or silage (P &lt; 0.03). Addition of CM or FM tended to decrease ADF digestibility of silage-based diets (P &lt; 0.06). Apparent ADF digestibility of hay-based diets was lower in lambs fed CM than in those fed FM (P &lt; 0.02). Forage DM intake was similar for all treatments. Addition of CM or FM to the diets improved average daily gains by 24% (P &lt; 0.03), an effect that was higher with hay (35.1%, P &lt; 0.02). Feed efficiency was 23.6% better in lambs fed protein-supplemented hay than in those receiving C (P &lt; 0.04). Neither dressing percentage nor carcass lean yield was affected by protein supplementation. Digestible DM and TDN intakes were higher in lambs fed silage (P &lt; 0.03) as a result of higher apparent digestibility for silage than hay. Furthermore, CM increased TDN intake by 7.6 and 8.2% in lambs fed hay and silage, respectively, compared with lambs fed FM. Addition of canola and fish meals improved forage nutritive value for lambs. Key words: Canola meal, fish meal, forages, digestibility, lambs, growth

Influence of feeding protected protein and energy on intake and digestion by lambs

To determine the effect of additional protected protein and energy on intake and digestion in lambs, a trial was conducted using 36 young sheep (average body weight 24 .8 _+ 1 .7 kg) in a completely randomized design . Combination of three levels of protected protein (0, 10 and 20%, based on the dry matter of the concentrate offered) and three levels of protected energy (0, 5, 10%, based on the dry matter of the concentrate offered) were added into concentrate diet and fed to growing sheep. Results showed that different levels of feed additive did not affect (P>0 .05) intake of dry matter, organic matter, neutral detergent fiber, acid detergent fiber and metabolizable energy, with average of 76 .3 g, 68.9 g, 31 .2 g, 16 .79 g and 0.75 MJ /kg BW0.75 respectively . Level of protected protein gave significant (P<0 .05) respons on crude protein intake (7 .4 vs 8.7 vs 9.8 g/kg BW0.75) . Combination of protected protein and energy did not affect animal ability to digest the nutrient effectively. A mixtures of 20 % protected protein and 5 %energy addition into concentrate diet increased average daily gain (ADG) as much as 100 g. It was also found that for every gram ADG needs 42.2 kJ metabolizable energy . Key words : Protein, protected energy, sheep

Correlation of Acid Detergent Lignin and Klason Lignin with Digestibility of Forage Dry Matter and Neutral Detergent Fiber

The acid detergent lignin and Klason lignin methods were compared for their correlation with forage digestibility. Thirty-six forages, including C3 legumes and C3 and C4 grasses, were analyzed for sulfuric acid detergent lignin, Klason lignin, and in vitro digestibilities of dry matter (DM) and neutral detergent fiber (NDF). Twenty of these forages were also fed to lambs at restricted intake for measurement of DM and NDF digestibilities. Lignin concentrations determined by the two lignin methods were positively correlated, and the Klason lignin value was always greater than the acid detergent lignin concentration. The largest differences were observed for grass forages. Digestibilities of forage DM and NDF were negatively correlated with both lignin methods for the in vitro system and the lamb digestibility trials. The degree of correlation for the two lignin methods with digestibility was generally similar across all forages and within forage classes. Slopes of linear regressions of digestibility on lignin concentration did not differ between legumes and grasses. Although the sulfuric acid detergent lignin and Klason lignin procedures gave very different estimates of forage lignin concentration, they were similarly correlated with digestibility and should yield predictions of forage digestibility that have similar accuracy.

Composition, digestibility and utilization of endophyte-free tall fescue fed as green-chop or hay to sheep

Two lamb digestion trials were conducted using three cultivars of endophyte-free tall fescue ( Festuca arundinacea Schreb.) that had been harvested from paddocks as green-chop forage of initial growth or as regrowth hay. The tall fescue cultivars were Johnstone (JOHN), AU Triumph (AUT) and Kentucky 31 (KY-31). All cultivars within each harvesting method contained similar quantities of dry matter (DM) and organic matter (OM). Both JOHN green-chop and hay contained more crude protein (CP) than the corresponding harvest of AUT or KY-31. Green-chop JOHN contained less ( P < 0.10) acid detergent fiber (ADF) and neutral detergent fiber (NDF), whereas JOHN hay contained more ADF and NDF than AUT or KY-31. The DM, OM, CP, ADF and NDF of JOHN green-chop were more digestible ( P < 0.10) than KY-31 or AUT. The same trend existed for hay, but digestibility of OM and CP did not differ between John and KY-31. The DM, OM, ADF and NDF digestibilities of AUT were greater ( P < 0.10) than KY-31 when harvested as green-chop forage and fed to lambs. No differences in digestibilities of DM, OM, N, ADF or NDF of AUT and KY-31 were observed when fed as hay. Ingestion and excretion of N were greater ( P < 0.10) in both trials for lambs fed JOHN. However, N retention was similar for all lambs except for reduced ( P < 0.05) N retention by lambs fed KY-31 green-chop forage. It can be inferred from these results that the DM, OM, ADF and NDF contents of Johnstone tall fescue are more digestible than Kentucky-31 or AU Triumph when fed to sheep as hay or green-chop forage when harvested in a vegetative stage.

Effects of chemically treated, recycled newsprint on feed intake and nutrient digestibility by growing lambs.

In situ experiments and two lamb digestion trials were conducted to evaluate the effects of chemically treating recycled newsprint (NP). Treatment of NP with 2% HCl (percentage of NP DM) followed by autoclaving for 4 h was most efficacious and was used in an in vivo digestion trial with 25 ram and wether lambs in a randomized complete block design (RCB). On a DM basis treatment diets were: 1) control, 95% alfalfa hay (AH); 2) 75% AH, 20% HCl-treated NP (HCl-NP); 3) 55% AH, 40% HCl-NP; 4) 75% AH, 20% untreated NP; and 5) 55% AH, 40% untreated NP on a DM basis. Lambs fed Treatments 2 and 3 had ad libitum DMI (1,043 and 1,036 g/d, respectively) similar to the DMI of those fed the control treatment (1,024 g/d); however, lambs fed Treatments 4 and 5 had lower (P < .05) ad libitum DMI (578 and 426 g/d, respectively) than lambs fed Treatments 1, 2, and 3. Apparent DM digestibilities were lower (P < .05) by lambs consuming Treatments 2, 3, 4, and 5 (52.6, 44.5, 52.0, and 48.2%, respectively) than by those consuming Treatment 1 (60.7%). Apparent OM, CP, NDF, and ADF digestibilities followed trends similar to DM. In the second digestion trial, 15 ram and wether lambs were used in a RCB to compare Treatments 1, 2, and 3. For this second digestion study, NP was treated with 4% HCl (percentage of NP DM), autoclaved for 4 h, and diets were fed at 2% of BW. As in Trial 1, apparent nutrient digestibilities decreased (P < .05) with increasing amounts of HCl-NP. Our results suggest that HCl-NP can be fed to sheep at 40% of the diet without a decrease in DMI; however, apparent nutrient digestibility decreases with increasing levels of HCl-NP.

Nitrogen and energy metabolism and serum constituents in lambs given broiler poultry litter processed by three deep-stacking methods

AbstractPoultry litter has been used as an economical nitrogen (N) source in ruminant diets. However, litter must be processed to eliminate pathogens. Broiler poultry litter was processed by three different deep-stack methods: (1) uncovered, (2) covered with 0.1524 mm clear polyethylene, and (3) aerated by placing perforated pipe 1 m apart within the stack. Stack temperature was measured for 28 days. The litter was used to formulate experimental diets (186 g litter per kg), while the control diet contained urea as the N source. All diets contained 100 g/kg cottonseed hulls, 16 to 17 g/kg limestone, varying amounts of cracked maize and added retinol. The control diet contained 131 g/kg crude protein (CP) while the litter diets contained 125 g/kg CP. The diets were offered to 16 crossbred wether lambs (37 (s.e. 6·1) kg) in individual metabolism crates for 16 days. Blood was collected at the initiation and termination of the trial. Covering litter with plastic decreased temperature ivithin the stack (P &lt; 0·05). Maximum temperature for the uncovered, covered and aerated stacks was: 68°C, 57°C and 72°C, respectively. Dry-matter intake and dry matter, energy and neutral-detergent fibre apparent digestibilities were not different (P &gt; 0·05) among the diets. Apparent digestibility for N was less (P &lt; 0·05) in lambs given uncovered and aerated litter than in those given the control diet. However, N apparent digestibility in lambs given covered litter was not different from that of those given the control diet. Gross energy and N retention of the four diets were not different (P &gt; 0·05). Covering deep-stacked broiler poultry litter improved N digestibility by proportionately 0·15 compared with uncovered litter. Serum chloride was decreased while serum urea was increased (P &lt; 0·05) in sheep consuming the litter-containing diets. Deep-stacked broiler litter should be covered in an air-tight manner in order to maximize its nutritive value.

Energy value of hominy feed for finishing ruminants.

Three trials were conducted to evaluate the energy value of hominy feed in finishing diets for ruminants. Hominy feed contained 56.9% starch, 25.2% NDF, 11.1% CP, and 5.3% fat (DM basis). In all trials, hominy feed replaced dry-rolled corn. As the level of hominy feed or ground corn increased in a lamb digestion trial, DM digestibility decreased (P < .01); however, starch digestibility increased (P = .09). Hominy feed and ground corn interacted (linear, P = .08) with respect to NDF digestibility. As the level of ground corn increased, NDF digestibility decreased (linear, P = .10). In a finishing trial, yearling heifers were fed either hominy feed with or without fat added to hominy feed at 0, 13.3 (.67% added fat), 26.7 (1.33% added fat), and 40.0% (2.0% added fat) of diet DM. Fat addition did not interact with hominy feed level. Heifers fed 13.3 or 26.7% hominy feed or hominy feed + fat consumed more DM (P = .10) than heifers fed the 0 or 40.0% diets; however, gain and feed efficiency were similar. In a second finishing trial, steers fed 40% (diet DM) hominy feed consumed more (P = .05) DM, but daily gain and feed efficiency were similar to those of cattle fed dry-rolled corn. Steers fed all-concentrate diets were more efficient (P < .01) than cattle fed 7.5% forage. Results indicated that expeller-extracted hominy feed contained 1.35 Mcal of NEg/kg, or 87% of the energy of corn, when included at levels up to 40% of cattle finishing diets, despite its containing 20% less starch than corn.

The effect of diet composition on the development of rumen digestion in lambs.

The effect of composition of feed concentrate on the development of rumen digestion in suckling lambs was investigated. The experimental group of lambs was offered special concentrate diets (SCD I and SCD II), which, compared to routinely produced commercial mixtures CCD 1 and CCD 2, were completely cleared of milk protein, enriched with legumes and alfalfa meal and supplemented with cut alfalfa of the particle size 1 cm. Significantly higher concentrations of total volatile fatty acids (VFA) were recorded in experimental lambs at the age of 7, 9 and 11 weeks. The highest concentration of total VFA was observed at the age of 11 weeks (118.2 mmol.l-1 in the experimental group and 110.2 mmol.l-1 in the control group). The cellulase activity (endoglucanase E.C.3.2.1.4. and cellobiohydralase E.C 3.2.1.91.) of the rumen content of experimental lambs was significantly higher at the age of 9, 11 and 15 weeks, in comparison with the control animals, reaching the highest values at 11 weeks of age (19.32 micrograms.ml-1 in the experimental group, 15.84 micrograms.ml-1 in the control group), while the increase of number of cellulolytic bacteria in experimental lambs was insignificant. Scanning electron microscopy showed more pronounced colonization of the rumen epithelium by adherent rumen microflora in experimental lambs. Average daily weight gains over the whole investigated period reached 0.235 kg in the experimental group and 0.221 kg in the control group.

Effects of starch on ruminal fermentation and detergent fibre digestion in lambs fed bermudagrass hay

Twelve cannulated Suffolk wether lambs (30.1 kg) were used in a randomised complete block design experiment to determine the effects of increasing dietary concentrate (corn starch-based) on ruminal digestive kinetics and fermentation characteristics and digestion of bermudagrass hay (BGH) fibre in lambs. Treatments consisted of as-fed concentrate:BGH ratios (C:F) of 10:90, 40:60 and 70:30. Ruminal digestion of neutral detergent fibre (NDF) and hemicellulose (HC) declined linearly ( P < 0.01) with increasing C:F. Quadratic responses to post-ruminal ( P < 0.10) and total tract ( P < 0.05) digestion of HC were obtained with increasing C:F. Total tract digestion of NDF declined linearly ( P < 0.05) with increasing C:F. Extent of acid detergent fibre (ADF) digestion was not affected ( P > 0.10) by C:F at any digestive site. Integrated pH-hours below pH 6.7 declined linearly ( P < 0.01) with increasing C:F and was correlated with ruminal digestion of NDF ( r = −0.75, P = 0.005) and HC ( r = −0.67, P = 0.018). Ruminal volatile fatty acid (VFA) concentrations increased linearly ( P < 0.01) with increasing C:F and were correlated with ruminal digestion of NDF ( r = −0.88, P = 0.001) and HC ( r = −0.82, P = 0.001). Ruminal liquid turnover was not affected ( P > 0.10) by C:F. Ruminal forage particulate passage rate tended ( P = 0.12) to increase with increasing C:F and was correlated with the ruminal digestion of both NDF ( r = −0.67, P = 0.023) and HC ( r = −0.57, P = 0.063). While virtually all potentially digestible ADF (cellulose) was digested in the rumen, ruminal escape of HC increased with increasing C:F. Data suggest that HC is the cell wall fraction of BGH that is the most sensitive to dietary starch level.

Hydrolysis time as a factor affecting the nutritive value of feather meal and feather meal-blood meal combinations for growing calves.

The objectives of this research were to determine 1) the effects of hydrolysis time on feather meal (FTH) protein digestion and ruminal escape and 2) whether adding blood meal (BM) to FTH evoked a complementary response in animal performance. A lamb digestion trial was conducted to estimate true protein digestibility of soybean meal (SBM), BM, and FTH hydrolyzed for 10, 12, 15, or 18 min. Ruminal escape was estimated in situ. Two 94-d growth trials were conducted using 60 growing calves (226 kg) per trial to evaluate urea, FTH, BM, and 87.5:12.5, 75:25, and 50:50 combinations (CP percentage basis) of FTH:BM. There were small numerical differences in estimated escape of protein from the rumen and DM and protein digestibilities due to hydrolysis time. True protein digestibility of the 10- and 18-min samples was 5% higher (P less than .05) than for the 12- or 15-min FTH samples. In the growth trial, the slope-ratio technique showed that the most efficiently used protein supplement was 100% BM (protein efficiency = 2.45 +/- .19). No differences (P = .30) in protein efficiency were observed among supplements containing various combinations of FTH:BM. There was a quadratic (P less than .01) response to the level of BM, indicating a complementary effect. The largest complementary effect occurred at the 12.5% level of the BM addition. There were no nutritionally important effects of hydrolysis time between 10 and 18 min. Furthermore, supplements can be formulated more economically using small amounts of BM with FTH without compromising biological efficiency.

Factors limiting the intake of feed by sheep. 15. Voluntary feed consumption and digestion in lambs fed chopped roughage diets varying in quality

Feed intake and digestion transactions for diets based on wheaten straw and mature ryegrass diets, both supplemented to provide additional essential nutrients, were compared with those for lucerne hay and high quality forage oats diets in lambs weighing c. 24 kg. The data obtained and comparable published data were used to examine relationships between a range of variables. Decrease in roughage quality, as evidenced by decrease in digestible organic matter (OM) intake, was accompanied by increase in (i) times spent eating, ruminating and chewing rumination boluses, (ii) the quantities of digesta or digesta OM in the reticula-rumen and omasum. It was not associated with increase in the large particle content of rumen or omasum digesta. Over the range of diets, close direct relations were demonstrated between (i) ruminating time and the amount of digesta in the reticulo-rumen, (ii) the amounts of digesta in the reticulo-rumen and omasum, (iii) the OM concentrations in rumen and reticulum digesta, (iv) the OM concentrations in reticulum and omasum digesta, (v) the OM concentration of reticulum digesta and of digesta flowing to the omasum, and (vi) the increase in OM concentration from reticulum to omasum digesta and OM concentration of reticulum digesta. Reticulum digesta were of finer texture than rumen digesta, and the bulk density of digesta particle fractions varied between diets, and sometimes between rumen and large intestine digesta. With a straw-based diet, relative to lucerne hay, small particles ( &lt;600 �m sieve) were cleared more slowly from the reticula-rumen, associated with a larger reticulo-rumen particle pool. The data are discussed in relation to (i) the flow of digesta through the alimentary tract and (ii) the regulation of roughage intake. They were considered to be consistent with a concept that energy metabolism and digesta load in the reticulo-rumen interact in the regulation of roughage intake.

Digestibility by Lambs of Water-Stressed Alfalfa as Determined by Total Collection or Internal Markers

A lamb digestion trial was conducted to compare the ability of internal markers to predict digestibility of alfalfa. Lambs were fed alfalfa hay grown with varying amounts of water stress where water per harvest ranged from 10 to 20 cm/ha and yield ranged 1400 to 4200kg/ha. In vivo dry matter digestibility was most highly correlated with digestibility determined using acid detergent fiber insoluble ash (r = .80) followed by acid insoluble ash (r = .69). In vivo digestibility of the fibrous components was most highly correlated with digestibility determined by acid detergent insoluble ash and indigestible neutral detergent fiber followed by acid lignin and acid insoluble ash.

Digestibility and rate of passage by lambs of water-stressed alfalfa.

Two lamb digestion experiments were conducted to evaluate the effect of alfalfa [Medicago sativa (L.)] grown under varying levels of water deficiency (stress) on the rate of passage and digestibility of various fibrous components. Experiment 1 consisted of a randomized complete block design in which 12 Suffolk X Hampshire crossbred wethers averaging 40 kg were fed alfalfa hay grown at three (10, 15 or 20 cm water/ha) levels of water per harvest. Experiment 2 consisted of a switchback design in which four Hampshire wethers averaging 45 kg were fed alfalfa hay grown at two (5 or 20 cm/ha) levels of water per harvest. Forage yields ranged from 1,420 (10 cm/ha in Exp. 1) to 4,200 (20 cm/ha in Exp. 2) kg/ha. In both experiments, water stress reduced cell wall constituents (neutral detergent fiber), acid detergent fiber, lignin and cellulose content of the alfalfa hay. Organic matter digestibility was decreased when the percentage of leaves fell below 60% at the highest yield. Digestibility of N and the rate of NDF digestibility were not affected by water stress. The second experiment additionally included nutrient balance and rate of passage measurements. Greater (P less than .10) amounts of N and P were absorbed from water-stressed than nonstressed hay. Ruminal retention time of particulate markers tended (P less than .10) to increase with greater water stress. The results of this study are interpreted to indicate that while moderate water stress may have little effect on in vivo digestibility of alfalfa, severe stress may reduce digestibility of fibrous fractions and total organic matter.