Ruminal CP Degradation Research Articles

Evaluation of sorghum dried distillers’ grains plus solubles as a replacement of a portion of sorghum grain and soybean meal in growing diets for steers

The objective of this study was to determine the effect of concentrations of sorghum dried distillers’ grains plus solubles (SDDGS) in growing feedlot diets on animal performance, ruminal passage rate and digestion. Two experiments were conducted evaluating four isonitrogenous total mixed rations (TMR) as dietary treatments, offered ad-libitum, with increasing levels of SDDGS 0%, 15%, 30%, and 45%, replacing a combination of sorghum grain and soybean meal. In Experiment 1, 32 Hereford steers (198.8 ± 14.6 kg) were randomly assigned to one of four dietary treatments and fed in individual pens over the course of 70 days. Average daily gain, final BW, and ribeye area exhibited a quadratic response (P ≤ 0.05). Reaching maximum values with 18.2% to 19.6% of SDDGS concentration in the TMR. There were no differences in DM intake and backfat thickness (P ≥ 0.23). Feed efficiency (P = 0.0002) and dietary net energy (P = 0.027) decreased linearly with greater SDDGS concentration in the TMR. Based on growth performance data, the estimated SDDGS NE value was similar to grain sorghum at inclusion level of 30%, but at higher levels of inclusion, the energy value of SDDGS was negatively affected, with a decrease of 24% for 45% inclusion level. In Experiment 2, four ruminally cannulated steers (450 ± 63 kg) were assigned to the same dietary treatments as in Experiment 1 in a 4 × 4 Latin square design. Physically effective fiber (peNDF) and NDF content of the TMR increased linearly (P < 0.0001) with increasing levels of SDDGS. Greater concentrations of SDDGS in the TMR led to a linear increase in NDF and EE intake (P < 0.001) with no effect on DM and CP intake (P ≥ 0.17). Metabolizable energy intake (P = 0.09) demonstrated a linear tendency of increase with greater SDDGS concentration. Ruminal degradability of DM and CP decreased linearly (P ≤ 0.01). Ammonia concentration decreased linearly (P < 0.0001) with no changes in ruminal pH (P ≥ 0.75) as concentrations of SDDGS increased. Sorghum DDGS is a suitable ingredient for feedlot cattle diets. At 15% and 30% inclusion level, the NE value of SDDGS is similar than sorghum grain, and allows to achieve a greater growth performance. Replacing sorghum grain beyond 30% with SDDGS, the NE value of SDGGS linearly decrease by increasing dietary lipid and by replacing starch of grain with NDF of SDDGS.

Comparison of milk production, intake, and total-tract nutrient digestion in lactating dairy cattle fed diets containing either wheat middlings and urea, commercial fermentation by-product, or rumen-protected soybean meal

The objective of this study was to evaluate the effects of a commercially available fermentation by-product in a diet containing adequate rumen-degradable protein (RDP) on milk performance, intake, and total-tract nutrient digestion in lactating dairy cattle. Primiparous (n = 48) and multiparous (n = 144) lactating dairy cattle were stratified by milk production and randomly allocated into 12 pens containing 4 primiparous and 12 multiparous animals each. Cattle averaged 118 d in milk and 712 kg of body weight at trial start. Treatment diets, on a dry matter (DM) basis, consisted of 42% corn silage, 13% alfalfa hay and silage, 20% grain corn, and 25% protein premix containing either soybean meal, wheat middlings, and urea (SBM+U), soybean meal and fermentation by-product (SBM+F), or soybean meal and rumen-protected soybean meal (RP-SBM). All 3 diets provided a similar level (DM basis) of neutral detergent fiber analyzed using α-amylase and sodium sulfite and corrected for ash content (31%), crude protein (CP, 14.9%), starch (26%), and metabolizable energy (2.7 Mcal/kg), and differed in sources of RDP. The trial consisted of a 2-wk adaptation and covariate period during which all cows were fed the RP-SBM diet and covariate measurements were taken. Pens were then randomly allocated to treatments, and weekly measurements of milk production, intake, body weight, and condition score were taken for 10 wk. All data were analyzed using the Proc Mixed procedure in SAS (SAS Institute Inc., Cary, NC). Increased DM intake was observed for cows fed SBM+F compared with cows fed SBM+U and RP-SBM (28.3 vs. 26.9 and 26.7 kg/d, respectively). Cows fed SBM+F produced more energy-corrected milk (45.3 kg/d) compared with cows fed SBM+U and RP-SBM (43.6 and 43.7 kg/d, respectively). Milk protein yield was also increased in cows fed SBM+F. No differences were observed with body weight or condition score gain throughout the trial. Apparent total-tract digestibility of fiber was decreased in cows fed SBM+F, likely as a result of increased intake. Responses are consistent with previous research in our laboratory that demonstrated a decrease in ruminal CP degradation, leading to an increase in metabolizable protein supply in the small intestine. The fermentation by-product might be useful in diets containing adequate amounts of RDP from soybean meal or alfalfa. The results from this experiment demonstrate beneficial milk performance responses to fermentation by-product when fed with a source of RDP.

169 Increasing levels of sorghum dried distillers grains with solubles in feedlot diets: effects on nutrient digestibility, ruminal degradability and fermentation

Abstract The objective of this study was to determine the effect of increasing levels of sorghum dry distillers grains with solubles (DDGS) in high concentrate feedlot diets in the nutrient digestibility (%), ruminal degradability (%), pH, NH4 (µg N-NH4/ml) and volatile fatty acid (VFA, mM/l) concentration. Four ruminally cannulated steers (450 ± 63 kg) were used in a 4x4 Latin square design, evaluating four treatments in four periods of 19 days each, with 14 days of adaptation and 5 days of measurements. Animals received a TMR, 92% concentrate (63% sorghum grain, 25% soybean meal, 4% mineral commercial premix), with DDGS (90% DM, 29% CP, 51% NDF, 9% EE) in increasing levels generating 4 treatments: 0, 15, 30, or 45%. Replacing a combination of sorghum grain and soybean meal to maintain diets isoproteic. The TMR was offered ad-libitum to each animal in individual pens. Greater levels of DDGS increased the consumption of NDF (P = 0.0001) and EE (P = 0.0004), and NDF total tract apparent digestibility (linear; P = 0.038), but it decreased quadratically EE total tract apparent digestibility (P = 0.017). The DM (84.2 ± 0.17) and the CP total tract apparent digestibility (85.3 ± 2.0) was not affected by increasing levels of DDGS. Nevertheless, the ruminal degradability of total DM (P = 0.01) and CP decreased linearly (P = 0.01), without affecting NDF degradability (65.6 ± 4.3). Increasing levels of DDGS did not change ruminal pH (5.6 ± 0.14), acetate (45.1 ± 6.3), propionate (24.8 ± 3.6), and butyrate (5.2 ± 0.7) concentration, but NH4 concentration decreased linearly (P &lt; 0.0001) directly related to the decreased CP ruminal degradability. Increasing levels of DDGS inclusion in a high concentrate diet reduce the CP ruminal degradability, without changes in total CP digestibility, what indicates a change of the site of digestion.

Molecular Structure and Metabolic Characteristics of the Proteins and Energy in Triticale Grains and Dried Distillers Grains with Solubles for Dairy Cattle

To our knowledge, there is no research on the molecular structure of triticale grain in comparison with other types of cereal grains and metabolic characteristics of the protein and energy in this grain and its coproducts, called dried distillers grains with solubles (DDGS), for dairy cattle. The objective of this study was to identify differences in molecular structures of proteins among grains and their DDGS using a molecular spectroscopy technique, namely, DRIFT, and to determine the nutrient profile and supply to dairy cattle. The protein molecular structure studies showed a difference (P < 0.01) in the amide I to amide II ratio and the α-helix to β-sheet ratio between grains and their DDGS. The energy content was similar for triticale grain and DDGS. There were differences in the protein and carbohydrate subfractions (P < 0.05) and the ruminal degradability of DM, CP, and NDF (P < 0.01) between triticale grain and DDGS. Triticale grain and DDGS had similar intestinal digestibility of rumen undegraded CP. However, triticale DDGS had higher (P < 0.01) predicted total metabolizable protein and degraded protein balance than triticale, indicating that triticale DDGS is a superior protein source for dairy cattle as compared with triticale grain. Bioethanol processing induced changes in the protein molecular structure.

Influence of protein type and level on nitrogen and forage use in cows consuming low-quality forage

Minimal quantities of ruminally degradable protein from supplements may improve supplement use efficiency of ruminants grazing dormant forages. In Exp. 1, N retention, ruminal NH(3), serum urea N, and NDF digestibility were evaluated for 12 ruminally cannulated cows (Bos spp.) in an incomplete Latin Square design with 3 periods of 42 d each. Cows were fed weeping lovegrass [Eragrostis curvula (Schrad.) Nees] hay (4.1% CP, 75% NDF, OM basis) at 1.3 % BW/d and offered 1 of 3 sources of CP [urea, cottonseed (Gossypium spp.) meal (CSM); or 50% blood meal and 50% feather meal combination (BFM)] fed to supply 0, 40, 80, or 160 g/d of CP. Beginning on d 22 of supplementation, ruminal contents and serum samples were collected at -2, 0, 3, 6, 9, 12, 18, 24, 30, 36, and 48 h relative to the morning offering of hay. On Day 24, feces and urine were collected for 72 h. In Exp. 2, 4 ruminally cannulated steers were used in a replicated 4 by 4 Latin Square to evaluate use of supplements differing in quantity and ruminal CP degradability. Steers were fed 6.8 kg/d chopped sudangrass [Sorghum bicolor (L.) Moench nothosubsp. drummondii (Steud.) de Wet ex Davidse] hay (3.7% CP, 74% NDF on OM basis) and supplemented with 56 g/d of a salt mineral mix (CON); CON + 28 g/d blood meal + 28 g/d feather meal (BFM); CON + 98 g/d CSM (LCS); or CON + 392 g/d CSM (HCS). Treatments provided 0, 40, 40, or 160 g/d of CP for CON, BFM, LCS, and HCS respectively. In Exp. 1, N use and total tract NDF digestibility were not affected by protein sources or amounts (P ≥ 0.18). Ruminal NH(3) concentrations exhibited a quadratic response over time for UREA (P < 0.05) and was greater with increasing inclusion of urea (P < 0.05); whereas BFM or CSM did not differ (P > 0.05) by amount or across time. In Exp. 2, supplementation had a tendency (P = 0.09) to increase DM disappearance. Supplementation also increased (P < 0.01) serum glucose concentrations; however, no difference (P ≥ 0.28) was found between supplements. Serum urea N and ruminal NH(3) concentrations were increased (P ≤ 0.01) in steers fed HCS. Feeding low quantities of a high-RUP supplement maintained rumen function without negatively affecting DM or NDF digestibility of a low-quality forage diet.

Effects of increasing levels of corn distillers dried grains with solubles to steers offered moderate-quality forage1

Supplementation of forage-fed livestock has been studied for decades; however, as by-products become available research is needed to determine optimal feeding rates for increased efficiency. Five ruminally and duodenally cannulated beef steers (446 +/- 42 kg of initial BW) were used in a 5 x 5 Latin square to evaluate effects of increasing level of supplemental corn distillers dried grains with solubles (DDGS; 25.4% CP, 9.8% fat, DM basis) on DMI, rate and site of digestion, ruminal fermentation, and microbial efficiency. Diets consisted of ad libitum quantities of moderate-quality smooth brome hay (10.6% CP; DM basis), free access to water and trace mineral salt block, and 1 of 5 levels of DDGS (0, 0.3, 0.6, 0.9, and 1.2% of BW daily of DDGS; DM basis). Diets were formulated to meet or exceed the estimated rumen degradable protein requirements (assumed microbial yield = 10.5%). All supplements were fed at 0600 h before forage was fed. Steers were adapted to diets for 14 d followed by a 7-d collection period. Hay OM intake decreased (linear; P < 0.001), whereas total OM intake increased (linear; P < 0.001) with increasing DDGS level. Total CP intake, duodenal OM and CP flows, and total tract OM and NDF digestibilities increased (linear; P <or= 0.01) with increasing level of DDGS. Apparent ruminal and true ruminal CP digestibilities increased linearly (P <or= 0.007), and total-tract CP digestibility increased quadratically (P = 0.02) with increasing DDGS level. Average ruminal pH was not different (P = 0.89) among treatments. Ammonia concentration increased (quadratic; P = 0.02) with increasing DDGS. Acetate proportions (molar %) decreased linearly (P < 0.001), whereas butyrate (molar %) increased linearly (P = 0.007), and propionate (molar %) increased quadratically (P = 0.04) with increasing DDGS. Ruminal DM fill decreased quadratically (P = 0.03), whereas fluid dilution rate tended to increase cubically (P = 0.08) with increasing DDGS. In situ rate of hay and DDGS DM disappearance responded cubically (P <or= 0.03) with greatest disappearance occurring with the 0.9% treatment. In situ rate of ruminal CP degradation of hay and DDGS increased (linear; P <or= 0.003) with increasing DDGS. Feeding 0.3% up to 1.2% of BW daily of DDGS as a supplement to forage-based diets resulted in no adverse effects on forage digestion or fermentation and resulted in increased nutrient supply in steers fed moderate-quality smooth brome hay.

Ruminal degradation and intestinal digestibility of dried or wet distillers grains with increasing concentrations of condensed distillers solubles

The objective of this experiment was to determine the effect that the amount of condensed distillers solubles (CDS) added back to distillers grains (DG) and its form, wet or dried, have on nutrient digestion. Three Holstein cows with ruminal cannulas were used to evaluate in situ ruminal degradability of DM and CP and in vitro intestinal digestibility of CP. Condensed distillers solubles were added back to wet DG in the following ratios of wet DG to CDS: 100:0, 86.7:13.3, 73.3:26.7, and 60:40. One-half of each mixed feed at each ratio was dried, and the other one-half remained wet, resulting in 8 DG samples. Feeds were incubated in the rumen for 0, 3, 6, 12, 18, 24, and 48 h. Intestinal CP digestibility was measured on residue from 12-h ruminal incubation feeds by the pepsin-pancreatin method. The soluble fraction of DM and CP was greater (P < 0.001) for wet compared with dried DG and increased as CDS increased in each blend (P < 0.001). The potentially degradable fraction of DM and CP was greater (P < 0.001) for dried compared with wet DG and decreased as CDS increased in each blend (P < 0.01). The rate of DM and CP degradation was not (P > 0.05) affected by form or inclusion of CDS. Rumen-degraded DM was greater (P < 0.001) for wet compared with dried DG (59.7 vs. 48.6%), and as the percentage of CDS increased, it increased (P < 0.001) from 49.3 to 61.2%. Rumen-degraded protein (RDP) was greater (P < 0.001) for wet DG than dried DG (53.1 vs. 38.0%). In addition, RDP increased (P < 0.001) from 42.0 to 50.5% as the concentration of CDS increased from 0 to 40%. Estimated intestinal digestibility of rumen-undegraded protein was greater (P = 0.003) for wet DG compared with dried DG (69.7 vs. 64.0%), but was unaffected (P = 0.11) by the addition of CDS. Intestinal absorbable dietary protein was greater (P < 0.001) for dried DG (39.7%) compared with wet DG (32.7%), and decreased (P < 0.001) from 39.9 to 32.0% with increasing concentrations of CDS. Total digestible protein (TDP) increased (P < 0.001) from 77.7 to 85.8% for dried and wet DG, whereas different ratios of DG to CDS resulted in similar TDP. Based on this study, ruminal DM and CP degradability and intestinal protein digestibility of DG increased when the percentage of CDS increased. Although dried DG can supply more ruminal undegraded protein, wet DG can supply more TDP.

Consumo, digestibilidade aparente e desempenho de vacas leiteiras alimentadas com concentrado processado de diferentes formas

O objetivo neste estudo foi avaliar o consumo, a digestibilidade aparente, a degradabilidade ruminal da MS e da PB, a produção e a composição do leite de vacas leiteiras alimentadas com concentrado processado de diferentes formas. Foram utilizadas 16 vacas da raça Holandesa, puras e mestiças, em dois níveis de produção de leite (30 e 20 kg de leite/dia), distribuídas em quatro quadrados latinos (dois para cada nível de produção). O experimento foi constituído por quatro períodos de 15 dias. As dietas experimentais, isoprotéicas, foram formuladas à base de silagem de milho e apresentavam as relações volumoso:concentrado 50:50 e 60:40 (na MS), respectivamente, para proporcionar produções de 30 e 20,0 kg de leite/dia. A digestibilidade da MS não foi afetada pelo processamento, enquanto a da PB para vacas alimentadas com concentrado extrusado (72,36%) foi menor que a do concentrado farelado, no nível de 50% de concentrado. A digestibilidade da fibra em detergente neutro nas vacas alimentadas com concentrado extrusado (44,35%) foi menor no nível de 50% de concentrado. A produção de leite foi maior nos animais que consumiram concentrado extrusado (29,9 kg/dia) no nível de 50%. Contudo, não houve diferença significativa no menor nível de concentrado na dieta. A composição do leite não diferiu entre os tratamentos em ambos os níveis de produção.

Influence of dietary crude protein concentration and source on potential ammonia emissions from beef cattle manure1,2,3

Emissions of ammonia, as well as other gases and particulates, to the atmosphere are a growing concern of livestock producers, the general public, and regulators. The concentration and ruminal degradability of CP in beef cattle diets may affect urinary and fecal excretion of N and thus may affect ammonia emissions from beef cattle feed yards. To determine the effects of dietary CP concentration and degradability on potential ammonia emissions, 54 steers were randomly assigned to nine dietary treatments in a 3 x 3 factorial arrangement of treatments. Treatments consisted of three dietary CP concentrations (11.5, 13, and 14.5%) and three supplemental urea:cottonseed meal ratios (100:0, 50:50, and 0:100 of supplemental N). Steers were confined to tie stalls, and feces and urine excreted were collected and frozen after approximately 30, 75, and 120 d on feed. One percent of daily urine and feces excretion were added to polyethylene chambers containing 1,550 g of soil. Chambers were sealed, and ammonia emissions were trapped in an acid solution for 7 d using a vacuum system. As the protein concentration in the diet increased from 11.5 to 13%, in vitro daily ammonia emissions increased (P < 0.01) 60 to 200%, due primarily to increased urinary N excretion. As days on feed increased, in vitro ammonia emissions also increased (P < 0.01). Potential ammonia losses were highly correlated (P < 0.01) to urinary N (r2 = 0.69), urinary urea-N (r2 = 0.58) excretion, serum urea-N concentration (r2 = 0.52), and intake of degradable protein N (r2 = 0.23). Although dietary composition can affect daily ammonia losses, daily ammonia emissions must be balanced with effects on animal performance to determine optimal protein concentrations and forms in the diet.

Ruminal fermentation and degradation patterns, protozoa population and urinary purine derivatives excretion in goats and wethers fed diets based on olive leaves1

Olives leaves, accrued during the processing of olive harvests for oil extraction, are poor in N, rich in crude fat and ADF (1.19, 8.03 and 28.2 g/100 g of DM, respectively), and relatively low in condensed tannins (11.1 mg/g of DM). Three experiments were conducted in a 2 x 3 (two animal species: goats vs. wethers; and three experimental diets: olive leaves without or with polyethylene glycol supply and olive leaves supplemented with barley and faba beans) factorial design to evaluate ruminal degradation and passage kinetics (Exp. 1), fermentation pattern and protozoa population (Exp. 2), and urinary purine derivatives excretion (Exp. 3). Polyethylene glycol was supplied to evaluate the effects of condensed tannins contained in olive leaves. Ruminal degradability of CP was low in both goats and wethers, although goats showed higher (P < 0.05) values than wethers. Supplementation of olive leaves with barley and faba beans increased (P < 0.001) ruminal degradability of DM and CP. Both goats and wethers fed olive leaves showed similarly low particulate fractional passage rates (0.021 and 0.023/h, respectively). Ingestion of olive leaves promoted low NH3-N and VFA concentrations, which reflect poor microbial activity. These concentrations, especially that of VFA, increased when barley and faba beans were added. Ingestion of olive leaves affected ruminal protozoa: Entodiniomorphida showed low concentrations and Holotricha completely disappeared. When animals received a diet based on olive leaves, barley, and faba beans, Holotricha appeared in the ruminal liquor and Entodiniomorphida increased (P < 0.001). In goats and wethers fed olive leaves alone, urinary allantoin excretion was very low (163 and 164 micromol/kg BW0.75 in goats and wethers, respectively), and moderate values (352 and 389 micromol/kg BW0.75 in goats and wethers, respectively) were observed when a diet of olive leaves, barley, and faba beans was fed. The polyethylene glycol supply did not have an effect in goats or in wethers, indicating the lack of an effect of condensed tannins in olive leaves. Ingestion of olive leaves promotes a low microbial activity, although its supplementation with readily degraded carbohydrates and protein improves microbial activity and, as a consequence, increases its ruminal degradation. In general, for most of the measured variables, there were no animal species x diet interactions. Thus, goats and wethers had similar ruminal activities when fed diets based on olive leaves.

Effects of extrusion of flaxseed on ruminal and postruminal nutrient digestibilities

A study was conducted to determine the effects of extrusion on ruminal, post-ruminal and whole tract digestibility of flaxseed. Extrusion was performed at 155°C with a residence time of 43 s. Two non-lactating Holstein cows fitted with ruminal and duodenal cannulas were used in a randomized complete block design. Results showed that extruded flaxseed had higher (P < 0.05) in situ soluble and lower (P < 0.05) slowly degradable DM and CP fractions than unheated flaxseed. Extrusion increased (P < 0.05) ruminal DM and CP degradability of flaxseed by 7 and 13%, respectively. Ruminal undegraded DM, CP and NDF were all lower (P < 0.05) for extruded flaxseed than for unheated flaxseed. Extrusion increased (P < 0.05) ruminal degradability and reduced (P < 0.05) post-ruminal availability of most amino acids of flaxseed. Whole tract digestibility of DM, CP, NDF and amino acids were higher (P < 0.05) for extruded than for unheated flaxseed. It was concluded that extrusion under the conditions used in the present experiment increases ruminal and whole tract nutrient degradabilities of flaxseed and therefore was ineffective in increasing the post-ruminal supply of amino acids from flaxseed.

Ruminal degradability and in vitro intestinal digestibility of sunflower meal and in vitro digestibility of olive by-products supplemented with urea or sunflower meal: Comparison between goats and sheep

The in vitro digestibility of two-stage dried olive cake (TSDOC) and olive leaves (OL) unsupplemented or supplemented with increasing amounts of urea (U) or sunflower meal (SM) (0, 1.5, 2 and 2.5 g/100 g organic matter (OM) of the by-product) was determined. Chemical and amino acid composition, in vitro digestibility, in situ rumen degradability of crude protein and amino acids, and in situ–in vitro intestinal digestibility of SM CP and amino acids was determined. The in sacco rumen degradability and in vitro intestinal availability of CP and individual amino acids were also determined. Results obtained in Granadina goats and Segureña wethers were compared. SM provides arginine, glycine and aspartic and glutamic acids. The addition of increasing amounts of U or SM improved ( P<0.001) the IVDMD and IVOMD of both TSDOC and OL. There was no effect ( P>0.05) of the rumen inoculum origin on in vitro TSDOC digestibility. In contrast, values for OL were higher ( P<0.001) for goats versus sheep. In sacco ruminal CP degradability of SM was relatively high, and similar in sheep and goats (ED=0.78 and 0.75 for sheep and goats). Individual amino acid ruminal degradability had different values, being lowest for methionine, leucine, proline, tyrosine and cysteine. Values obtained for individual amino acids differed from those of CP. Apparent intestinal digestibility of undegraded protein (AIDUP) of SM was high (0.86 and 0.98, respectively, for sheep and goats). The intestinally absorbable protein (IADP) was low (18.9 and 24.0 for sheep and goats, respectively). Results indicate that goats and sheep have the same capacity for TSDOC digestion, but goats showed a better capacity than sheep for OL utilisation. Although the amino acids supply to the intestine from SM is not important it could be a good supplement for low degradable protein feedstuffs such as TSDOC and OL.

In situ dry matter and crude protein degradation kinetics of some forages in Eastern Turkey

Eight forages (dry grass hay, alfalfa, bromegrass, sainfoin, common vetch, oatgrass, wheat straw and barley straw) used for sheep nutrition in Eastern Turkey were evaluated for ruminal DM and CP degradation kinetics. Duplicate bags containing 3 g ground forages were incubated in the rumen of three ruminally cannulated Red Karaman rams for 4, 8, 16, 24, 48, 72 and 96 h. Rate and extent of ruminal digestion were estimated. Significant effects of forage species were observed in rapidly soluble and potentially degradable fractions, and degradation rates of DM and CP. The rapidly soluble DM and CP fractions were 17.4 and 30.3% for barley straw, 24.7 and 38.4% for wheat straw, 26.5 and 63.6% for oat grass, 29.0 and 29.7% for brome grass, 27.0 and 35.3% for alfalfa, 38.5 and 42.7% for sainfoin, 29.2 and 39.7% for common vetch, 28.0 and 31.0% for dry grass hay, respectively. The potentially degradable DM and CP fractions, respectively, were 49.7 and 26.5% for barley straw, 43.4 and 25.5% for wheat straw, 48.1 and 21.2% for oat grass, 46.8 and 49.6% for brome grass, 40.4 and 52.7% for alfalfa, 43.4 and 45.9% for sainfoin, 49.2 and 55.0% for common vetch, 55.4 and 50.0% for dry grass hay. The effective degradability (ED) of DM and CP were different ( P<0.01) between forage types.

Replacement of soybean meal and barley grain by chickpeas in lamb and kid fattening diets

In two trials, with 42 early-weaned male Chios lambs and 42 early-weaned Damascus kids, the effect of partial replacement of soybean meal and barley grain with chickpeas on weight changes and feed efficiency was studied. Within trial, animals were divided on the basis of age and liveweight into three groups that were randomly allocated to the concentrate mixtures containing three levels (kg as fed basis/t) of chickpeas (CHPEA 0, CHPEA 136, CHPEA 329). In situ degradation of soybean meal and chickpeas was also measured using three mature rumen fistulated Chios ewes. Apparent digestion coefficients and CP-retained were measured using four lambs per concentrate mixture. Lambs grew faster than kids. In both trials, there were no differences among diets in liveweight gain. Digestion coefficients of dry matter (DM), organic matter (OM) and CP in the diets containing chickpeas were higher than those on the soybean meal control diet. The effective ruminal degradability of CP was higher in chickpeas than soybean meal. Fast growing lambs and kids consuming chickpeas (up to 329 kg/t) in substitution for barley grain and soybean meal performed as well as those on the control diet.

Effects of untreated and heat-treated canola presscake on milk yield and composition of dairy cows

Five primiparous and five multiparous Holstein cows were used in two Latin square design experiments to determine effects of feeding unheated and heated canola presscake on milk yield and composition, and milk fatty acid concentrations of lactating dairy cows. Five diets that differed in level and source of dietary fat were formulated: a low fat control diet with 30gkg−1 fat from tallow, an unheated canola presscake supplemented diet (50gkg−1 fat), a heated canola presscake supplemented diet (50gkg−1 fat), a high tallow plus unheated canola meal supplemented diet (50gkg−1 fat), and a high tallow plus heated canola meal supplemented diet (50gkg−1 fat). In sacco ruminal degradability of heated and unheated canola presscake was compared with that of heated and unheated canola meal in a randomized complete block design using two ruminally fistulated cows. Heat treatment reduced ruminal DM and CP degradability of canola presscake. Multiparous cows fed diets supplemented with heated or unheated canola presscake produced more milk than those fed diets containing similar levels of fat from tallow with heated or unheated canola meal, respectively. High levels of fat from any diet reduced milk fat percentage for cows of either parity. Feeding heated canola products increased milk and milk protein yields in primiparous cows only, but cows of both parities fed diets containing canola presscake produced milk with lower concentrations of C12:0, C14:0, and C16:0 fatty acids than cows fed the canola meal and tallow diets, although concentrations of C18:1 n-9 were unaffected by fat source or level. Feeding canola products to dairy cows can alter milk fatty acid profile, but only primiparous cows have increased productivity as a result of feeding heated, versus unheated, canola presscake.

The effects of corn milling coproducts on growth performance and diet digestibility by beef cattle.

Simmental x Angus weanling heifers (n = 96; 239 +/- 2.3 kg) were used in four replications to evaluate three dietary treatments in Trial 1. Treatments were cracked corn-hay diets supplemented with one of three corn milling industry coproducts: dry corn gluten feed (DCGF), dried distillers grains (DDG), and a new modified corn fiber (MCF). In Trial 2, ruminally cannulated mature crossbred beef steers (n = 4; 606 +/-60 kg) were used in a 4 x 4 Latin square with 11-d periods to determine digestibility and ruminal metabolism of limit-fed cracked corn-alfalfa haylage diets supplemented with cornstarch (CON), DCGF, DDG, or MCF. During Periods 3 and 4, an in situ study was conducted to compare the rate and extent of CP degradation of DCGF, DDG, and MCF. In Trial 1, there were no differences (P > .10) in initial weights or DM intake. Average daily gain and feed efficiency (G/F) were improved (P < .01) for heifers fed DCGF or DDG vs heifers fed MCF. In Trial 2, no differences (P > . 10) in digestibilities of any nutrients or in ruminal VFA concentrations were observed for steers fed coproducts. The CON supplementation decreased (P < .05) total dietary fiber (TDF) digestibility, improved (P < .10) digestibilities of DM and OM, increased (P < .05) total VFA concentrations and concentrations of propionate and valerate, and decreased (P < .05) concentrations of butyrate, isobutyrate, and isovalerate when compared with the coproducts. Dry corn gluten feed increased (P < .05) and DDG tended (P < .10) to increase percentages of the immediately soluble fraction of CP, and both had increased (P < .05) rates (Kd) and greater (P < .05) extent of ruminal CP degradation than MCF. These data suggest that DCGF and DDG may be utilized in limit-fed high-energy diets without sacrificing performance. Feeding of MCF resulted in poorer performance of heifers, suggesting a limited feeding value that results from high ADIN content and slow in situ protein digestion.

Supplemental cracked corn for steers fed fresh alfalfa: II. Protein and amino acid digestion.

The effects of different levels of cracked corn on N intake, ruminal bacterial CP synthesis, and duodenal flows and small intestinal digestion of amino acids (AA) in steers fed fresh alfalfa indoors were determined. Angus steers (n = 6; average BW 338 +/- 19 kg) cannulated in the rumen, duodenum, and ileum were fed each of five diets over five periods in a Latin square design with an extra animal. Steers consumed 1) alfalfa (20.4% CP, 41.6% NDF) ad libitum (AALF); 2), 3), and 4) AALF supplemented (S) with three levels of corn (.4, .8, or 1.2% of BW, respectively), or 5) alfalfa restricted (RALF) to the average forage intake of S steers. Average N intake and duodenal flow of nonammonia N (NAN) were greater (P < .01) in S than in RALF steers. Greater duodenal flows of NAN in S compared with RALF were due to a trend toward higher (P = .06) flows of both bacterial and dietary N. Levels of corn decreased (P < .01) linearly N intake and increased (P < .01) linearly duodenal flow of NAN owing to a numerical linear increase in nonbacterial N (P = .15) with no increase in bacterial N flow. Duodenal NAN flows as percentages of N intake increased (P < .01) linearly (69.3 to 91.0%) as corn increased. Ruminal NH3 N concentration, ruminal CP degradability, and the proportion of bacterial N in duodenal NAN were decreased (P < .01) linearly as corn increased. Efficiency of net microbial CP synthesis was not affected (P > .05) by treatment (average 42.6 and 30.9 g N/kg of OM apparently or truly digested in the rumen, respectively). Small intestinal disappearance of total N and individual AA, except for threonine and lysine, and small intestinal digestibility of N and individual AA, except for methionine, histidine, and proline, increased (P < .01) linearly with level of corn and were greater (P < .01) in S than in RALF steers. Supplementing corn to steers fed fresh alfalfa reduced ruminal N losses and CP degradability and increased the duodenal flow and the small intestinal disappearance and digestibility of total N and total, essential, and nonessential AA.

Evaluation of selected mathematical approaches to the kinetics of protein degradation in situ.

A linear model, two mathematical nonlinear models, and a curve-peeling procedure were used to estimate rate and extent of ruminal CP degradation of meat and bone meal (MBM) and soybean meal (SBM) from data obtained using the in situ Dacron polyester bag technique. Most of the values for extent of CP degradation of MBM were lowest when determined using curve peeling or the nonlinear models. In general, rates and extents of CP degradation of MBM estimated using the linear model and including ruminal incubations up to 12 h were greater than those obtained with the linear model and including ruminal incubations up to 24 h or up to 72 h. In addition, the models ranked the MBM samples differently for rate and extent of CP degradation. The results of the lack-of-fit test indicated that the linear model was inappropriate for estimating rate of degradation of MBM. However, CP degradation for SBM could be described by the linear model if long ruminal incubation times (greater than 48 h) were included in the calculations. Regression analyses were conducted to evaluate various compositional characteristics as predictors of CP degradation for MBM. Most of the correlation coefficients between CP degradation and the same independent variables were greater when the nonlinear models and curve peeling were used compared with the linear model. In general, the correlation coefficients between extent of CP degradation and the independent variables obtained with the linear model increased as the duration of ruminal incubations included in the model increased. Lysine concentrations, followed by CP solubility and ash content, were the best predictors of ruminal degradation of MBM protein. When using a specific mathematical model to predict CP degradation, analysis of residuals vs fitted and lack-of-fit tests should be performed to assess the validity of the model to describe the degradation patterns of the protein source under consideration. Also, long (at least 48 h) ruminal incubation times may be needed to correctly describe the pattern of CP degradation for MBM.

The effect of stage of harvest on the process of digestion in cattle fed winter oats indoors. II. Nitrogen digestion and microbial protein synthesis

The effects of dates of harvest of winter oats ( Avena sativa L.) on the sites of nitrogen (N) digestion and ruminal microbial CP synthesis were studied in cattle fed indoors. The forage was cut from randomly selected areas of a single field at five dates from autumn to spring: A (25 May, autumn); EW (25 June, early winter); W (9 August, winter); ES (22 September, early spring); LS (20 October, late spring). The trial was arranged as a completely randomized design considering dates of harvest as treatments. Two heifers weighing 567 ± 17.8 kg fitted with cannulas in the rumen, proximal duodenum and distal ileum were given ad libitum access to feed. Animals were dosed with chromic oxide and Co-EDTA as external markers. The N content of the forage (g kg −1 dry matter) varied between 37.2 in A and 16.5 in LS ( P < 0.0001) and N intakes (NI, g kg −1 live weight (LW)) ranged from 0.81 to 0.23 with the lowest value in LS ( P < 0.02). Mean ruminal ammonia (NH 3-N) concentration ranged ( P < 0.0005) from 32.5 mg dl −1 in A to 5.1 in LS. Non-ammonia N (NAN) flow to the small intestine ranged from 0.46 to 0.25 g kg −1 LW ( P < 0.001). For A, EW, and W forages the NAN flows in relation to NI ( NAN NI , g g −1) were lower ( P < 0.05; mean: 0.69) than in the ES and LS forages (mean: 1.12). The NAN NI was negatively related to NI kg −1 digestible OM intake (DOMI), NAN NI = 1.63 − 0.015 g NI kg −1 DOMI; ( r = −0.94; P < 0.001). Microbial CP synthesis (g N kg −1 OM apparently digested in the rumen, OMADR) ranged from 31.5 to 46.0, tended to be lower in A ( P < 0.15) than in other forages and averaged 0.69 of the duodenal NAN. Ruminal CP degradability (g g −1 NI) tended to be higher ( P < 0.13) in A (0.81) than in ES (0.65). The date of harvest of winter oats can influence ruminal N digestion and intestinal supply of N. Duodenal NAN flow is dependent on NI and NAN NI depends not only on NI, but also on OM digestibility of winter oats. A high ruminal ammonia concentration in winter oats with high N content may be due to inefficient microbial capture of ruminally degraded CP, even when the efficiency of microbial synthesis (g N kg −1 OMADR) may be high.

Effects of Processing Method on Degradation Characteristics of Protein and Carbohydrate Sources In Situ

Two ruminally cannulated Holstein cows in early lactation were used to determine the effects of heat treatment and particle size on fractional degradation rates and ruminal degradabilities of DM, CP, and total nonstructural carbohydrate of dry shelled corn and soybeans. A randomized complete block design with cows as blocks was used. Carbohydrate sources were cracked corn, chick cracked corn, finely ground corn, and steam-flaked corn. Protein sources were soybeans that were roasted at 144°C, cracked, or ground through a 4-mm screen and raw soybeans that were cracked or ground through a 4-mm screen. Reduction in particle size increased both degradability of CP and total nonstructural carbohydrate in the rumen. Heat treatment decreased degradability of CP and increased degradability of total nonstructural carbohydrate in the rumen for both protein and carbohydrate sources. Roasting of soybeans decreased degradability of all AA except Lys. However, reduction in particle size had a stronger effect than heat treatment on ruminal degradability of CP and AA of soybeans, but had the opposite effect on total nonstructural carbohydrate degradability from corn. Methionine, Leu, and Thr had the lowest ruminal degradability across all soybean sources, and Lys and Val were the most degradable. The AA profile of the RUP fraction of soybeans differed from that of the original feedstuff and was affected by processing method.