Estimation of faecal output, digestibility, and intake using a controlled release capsule of alkanes in early and late lactation dairy cows fed two levels of concentrate

Thirty-two dairy cows (663 ± 70; kg of BW ± SD) were allotted to a 2 × 2 factorial arrangement of treatments to evaluate the controlled release alkane capsule (CRC; C32 and C36) to estimate digestibility and dry matter (DM) intake in early and late lactation for diets based on low (LC, 30%) or high (HC, 60%) proportions of concentrate. Cows were dosed orally with a CRC into the rumen and digestibility was measured by total collection and estimated from the ratios of alkanes in the diet and faeces. Recoveries of endogenous (C31 and C33) and exogenous (C32 and C36) alkanes were higher and lower, respectively, for LC compared with HC. The effects of diet and the interaction between diet and lactation stage were well estimated (P < 0.05) when measured released rates of C32 and C36 were used to estimate DM digestibility although estimation with both alkanes indicated an effect of lactation stage, which was not observed when using data of measured DM digestibility. The faecal ratio of C31/C32 or C33/C32 showed no diet effect on DM intake estimation while measured DM intake was 22.6% higher for cows fed HC than for those fed LC. In conclusion, estimation of DM intake was inadequate although digestibility of DM was estimated from alkanes contained in the CRC. Key words: Dairy cows, alkane, intake

Effect of cultivars on in vitro and ruminal degradation of the nitrogen fraction in birdsfoot trefoil silage

Experiments were carried out to determine the effects of tannin content on N fractions and DM digestibility of birdsfoot trefoil harvested at 20% bloom stage. Five trefoil cultivars, harvested in both June and August, were used: Upstar, Mirabel, Empire, Leo, and Bt-8861. Forage was ensiled in 1.3-kg laboratory silos for 60 d with 4 silos per cultivar and harvest. Concentrations of DM and tannin in forage were determined prior to ensiling, and N fractions, DM digestibility, and pH in silage were also determined. Tannin concentration and protein N content of silage were lower in Empire than in the other cultivars. Ruminal degradability of DM and CP of Empire (low tannin) and Upstar (high tannin) birdsfoot trefoil were estimated with two fistulated cows using nylon bags that were incubated < or = 96 h. The DM-soluble fraction of Empire was significantly lower than that of Upstar for the first harvest only. This difference was partly due to the high proportions of dry shoots. The CP-soluble fraction of Empire was higher than that of Upstar, but the percentage of CP that was potentially degradable in the rumen was lower for Empire. This difference could result in different CP availability over time even for similar effective degradability of CP. Tannin had no additional effect on total CP degradability in the rumen.

In vivo and in vitro gastric emptying of milk replacers containing soybean proteins

Gastric digestion of three milk replacers for which protein was provided either exclusively by milk powder or partially (50%) by heated soybean flour or soybean protein concentrate was studied in vivo and in vitro. In vivo gastric emptying of protein fractions of the diets was measured in six preruminant calves fitted with reentrant duodenal cannulas and used in a double 3 x 3 Latin square design. In vitro gastric emptying was studied after hydrochloric acid and rennet digestion in an artificial stomach. In vivo and in vitro flow rates of 12% TCA-insoluble N and total N were higher for the soybean diets than for the milk protein diet, indicating that the incorporation of soybean protein prevented casein from clotting. Because of this faster gastric emptying, proteolysis in the stomach was reduced. However, gastric emptying of NPN (12% TCA-soluble N) was significantly decreased only in vitro. No difference existed between the two milk replacers containing either soybean flour or soybean protein concentrate. In vivo and in vitro results were correlated, suggesting that the in vitro method could be used to predict gastric digestion of protein fractions in vivo.

Effect of grain level and protein source on ruminal fermentation, degradability, and digestion in milking cows fed silage

Five primiparous Holstein cows (483 kg BW) of low productivity were used in a 4 x 5 incomplete Latin square design to study the effects of feeding two levels of grain containing soybean meal and one level of grain containing fish meal on feed intake, milk production, digestibility, and rumen fermentation. Animals all were fed alfalfa silage for ad libitum intake. Collection of data was between wk 11 and 24 of lactation. The four treatments were an all silage diet (control), silage and medium concentrate fed at 1.8% BW containing soybean meal, and silage and low concentrate fed at 1.3% BW containing either soybean meal or fish meal. Treatments other than control were designed to give similar CP intake from the concentrate, which was based on high moisture corn and cob meal. Milk production and composition were similar among treatments except for fat percentage, which was significantly lower for low grain soybean meal. Intake of DM was higher on medium grain soybean meal compared with the other treatments. Average BW and change in BW (.11 kg/d) were not affected by treatments. Digestibility of DM was higher for cows fed grain (68 to 73%) than for those fed the control diet (60%). Generally, feeding concentrate at 1.3 or 1.8% BW and supplementing with soybean meal or fish meal resulted in pH and concentrations of NH3 N and VFA similar to those observed on the all silage diet. Feeding concentrate at 1.3 or 1.8% BW and supplying fish meal or soybean meal did not change feed utilization enough to increase milk production in low producing cows compared with an all silage diet.

Milk production and milk composition of dairy cows fed Lac100® or whole flaxseed

Cows were fed whole flaxseed or calcium salts of soybean oil as a fat source. Cows fed flaxseed had lower (P < 0.01) milk yield and higher (P < 0.01) percentages of fat and protein than cows fed calcium salts. Feeding whole flaxseed and calcium salts of soybean oil increased, respectively, the concentrations of alpha-linolenic acid and conjugated linoleic acid in milk. Key words: Flaxseed, fatty acids, fat supplement

Intake, digestibility, and ruminal degradability of shredded hay

Thirty-two Outaouais intact male lambs averaging 39.1 kg were assigned randomly to a 2 x 2 factorial arrangement of treatments consisting of two forages and two methods of harvesting to determine intake and digestibility. The four treatments fed during the experiment consisted of alfalfa and timothy hays harvested with either a prototype mat maker or a conventional mower conditioner. Hays were fed for ad libitum intake for the entire experiment, and data on digestibility and intake were collected for 9 d after a 21-d adaptation. Ruminal degradability of DM, N, and ADF of hays was estimated with two fistulated cows using nylon bags incubated up to 96 h. Harvesting with the prototype mat maker compared with the conventional mower generally increased intake and digestibility of alfalfa and timothy hays. Ruminal degradability of DM and the potentially degradable fraction of DM and ADF was higher when hay was harvested with the prototype mat maker than with the conventional mower. The increased digestibility of hay harvested with the prototype mat maker could be explained by the increased digestibility in the rumen because harvesting with the prototype mat maker increased the potentially degradable fraction of DM and ADF. These results suggest that the digestible energy content of hay was increased by shredding.

Effects of lasalocid or monensin on in situ biohydrogenation of flaxseed and sunflower seed unsaturated fatty acids

The objective of this study was to compare the effects of two ionophores, lasalocid and monensin (24 mg kg-1 dry matter), on in situ biohydrogenation of C18:2 and C18:3 from whole sunflower seed and flaxseed, respectively. There were no treatment effects on biohydrogenation of C18:2. Ionophore supplementation did not affect the lag time, but monensin decreased the rate of biohydrogenation of C18:3 compared with control and lasalocid. Key words: Ionophore, monensin, lasalocid, biohydrogenation (in situ), sunflower seed, flaxseed

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 < 0.04). Addition of CM or FM improved apparent digestibility of energy and crude protein (CP) of lambs fed hay (P < 0.02) and CP digestibility of lambs fed silage (P < 0.01). Apparent digestibility of CP was higher in lambs fed FM than in those fed CM with either hay or silage (P < 0.03). Addition of CM or FM tended to decrease ADF digestibility of silage-based diets (P < 0.06). Apparent ADF digestibility of hay-based diets was lower in lambs fed CM than in those fed FM (P < 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 < 0.03), an effect that was higher with hay (35.1%, P < 0.02). Feed efficiency was 23.6% better in lambs fed protein-supplemented hay than in those receiving C (P < 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 < 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

Milk production and intake of lactating cows fed grass silage with protein and energy supplements

Primiparous (n = 8) and multiparous (n = 24) Holstein cows averaging 591 kg of BW (SE = 12) were allotted at 2 wk postpartum to eight blocks of 4 cows each on the basis of calving date and parity. Cows were fed timothy silage for ad libitum intake. The experiment was carried out between wk 4 and 15 of lactation. Cows within each block were assigned randomly to a concentrate containing soybean meal fed with corn, beet pulp, or a mixture of oats and barley (50: 50 on a DM basis) or fish meal fed with beet pulp. Concentrates were fed at about .8% of BW. The four treatments were designed to give similar CP and NEL intakes from the concentrate. Starch degradability and energy source (non-structural vs. structural carbohydrates) had no effect on total DMI of cows supplemented with soybean meal. Total DMI was similar for cows fed beet pulp with soybean meal or fish meal. Production of 4% FCM was on average 3.5 kg/d higher for cows fed beet pulp than starch. All cows gained BW. In low concentrate diets, beet pulp compared with starch improved N utilization of high moisture timothy silage by increasing production of 4% FCM without affecting total DMI; however, protein degradability does not seem to be important in low concentrate diets.

A comparison of five protein sources as supplements for growing steers fed grass silage

An experiment conducted at three sites in eastern Canada, Kapuskasing, Lennoxville and Nappan, compared the efficacy of five protein sources as supplements for growing steers fed grass silage. For 20 wk, a total of 171 growing beef steers, average initial weight 247 kg, were offered grass silage ad libitum, either alone or supplemented with isonitrogenous amounts of FM, SBM, CM, a mixture of corn gluten meal and blood and, at two sites, MM. There were no significant treatment-by-site interactions for any of the parameters measured. Combined across the three sites, liveweight gain was low on the all-silage diet, 0.51 kg d−1, and FM increased gain by 0.44 kg d−1 or 86%. Soybean meal, CM and the CGM/BM increased liveweight gain by an average of 0.35 kg d−1 or 68%, while MM increased gain by 0.28 kg d−1 or 58%. All supplements increased liveweight gain (P < 0.001) with FM being superior to the other sources (P < 0.01). The supplements increased total DM intake (kg 100 kg LW−1, P < 0.01) but had no effect on silage intake (P > 0.05). Gain/feed ratio was 0.091 on the all-silage diet and was increased (P < 0.001) by all supplements, with FM (0.142) being superior (P < 0.01) to the other protein sources which averaged 0.129. The supplements did not affect organic matter digestion (P = 0.06) in measurements made at Lennoxville. Rumen degradability did not explain the differences in the extent to which the protein sources improved the performance of growing steers. Key words: Steers, growth, grass silage, protein supplements

An oxalate-sodium hydroxide buffer to study the role of milk replacer coagulation in preruminant calves

An oxalate-NaOH buffer, which prevents coagulation in the abomasum of young calves, was added to a nonclotting milk replacer based on high heat skim milk powder, to investigate effects of this buffer on digestibility and metabolism of dietary components. Twelve Holstein male calves were allotted at random in two groups of six animals each and fed the experimental milk replacers from 3 to 17 d of age. Digestibility of dry matter, protein, and fat was similar for both control and buffered milk replacers. Concentrations of plasma glucose, triglycerides, alpha-amino nitrogen, and urea were the same in animals receiving buffer treated milk replacer and control diets. The data suggests that this oxalate-NaOH buffer would be suitable to prevent milk clotting in studies dealing with the importance of coagulation in digestion and metabolism in preruminant calves.

Effects of mechanical treatment of whole canola seeds on performance, diet digestibility and rumen parameters of lambs fed grass silage

Thirty-three lambs (25.2 ± 2.7 kg body weight) were used to determine if mechanical treatment of canola seed could improve the performance of growing lambs and diet digestibility. All lambs received a basal diet of 179 g d−1 of a 16% crude protein (CP) commercial concentrate and grass silage fed ad libitum. The basal diet was supplemented with the following dietary treatments (dry matter basis): C, a control supplement supplying 182 g of a mixture of 66% canola meal and 34% canola oil; WCS, 187 g of whole canola seeds; RCS, 188 g of rolled canola seeds; and GCS, 189 g of ground canola seeds. Dry matter intake was similar for all diets. Average daily gain (ADG) was 20% lower (P < 0.001) for lambs fed whole or crushed canola seeds than for those fed the C diet. Lambs fed GCS had intermediate ADG between those fed C and those fed WCS and RCS diets. In general, apparent digestibility of C was higher (P < 0.01) than that of WCS and RCS and digestibility of GCS was intermediate. Rumen pH and molar proportions of individual volatile fatty acids (VFA) were not affected by treatments. Rumen ammonia-N concentration was similar among treatments. Utilization of whole canola seeds as a protein and energy supplement to grass silage resulted in lower performance of lambs compared to that obtained with a mixture of canola meal and canola oil. Key words: Canola seeds, silage, lamb growth

Outcome of Bt transgenes and protein in corn silage, processed grains, and rumen content

The environmental impact of transgenic plants has been questioned due to the potential persistence of proteins encoded by transgenes and horizontal gene transfer from the plant to gut microbes. The outcome of the encoded Bt [cry1A(b)] protein and transgene fragments (CaMV-35S, cry1A(b), bar, and bla) was monitored in silage and processed grains of two commercial Bt11 (NK N44-P4 Bt LL and NK N27-M3 Bt LL) and one Bt176 (Elite N09-K9 Bt) corn hybrids. The three Bt-corn hybrids with their non-Bt isolines were field-grown in four replicates. Seven 1.4-kg capacity mini-silos were prepared per plot and then opened after 1, 2, 4, 8, 16, 32, and 64 d. For each hybrid, two 500-kg plastic bag silos were also prepared, sampled after 30 and 198 d, and used in a feeding trial. In the mini-silos, the transgene fragments could no longer be amplified 32 d after ensiling. In the 500-kg plastic bag silos, the transgene fragments were still detectable in the three Bt hybrid silages 30 and 198 d after ensiling. At ensiling, the Bt protein concentration was 2.69, 4.11, and 0.83 µg g-1 DM for the Bt hybrids N44-P4, N27-M3, and N09-K9, respectively. After 64 d of fermentation in the mini-silos, the concentration was 4, 2, and 1% of the initial concentration, respectively, but was 16, 9, and 9% after 198 d in the 500-kg silos. After stringent processing treatments, transgene fragments, except the bla gene fragment, could still be amplified from corn grains. The Bt protein concentration in corn grain of the three Bt hybrids (initially 61, 239, and 21 ng g-1 DM, respectively) decreased by 35, 74, and 67%, respectively, after micronization, by 92, 98, and 89% after extrusion, and by 100% after flaking. After 7 d of feeding Bt corn silage to six dairy cows, Bt protein increased in ruminal digesta with higher concentrations for Bt11 hybrids than the Bt176 hybrid; in all cases, however, concentrations were very low in forage digesta and below detection levels in rumen fluid. Key words: Transgenic maize, silage, processed grains, genetically modified plants, Bacillus thuringiensis endotoxin

Effect of intensity of maceration on digestibility and intake of alfalfa hay and silage fed to sheep

A study was conducted to determine the influence of intensity of mechanical conditioning on the nutritive value of alfalfa conserved as hay or silage. Fresh alfalfa was mowed and conditioned at three levels of maceration prior to field wilting during 45 h for silage (29–39% DM) or 94 h for hay (87% DM, after barn-curing), under light rain conditions during the first 2 d. The conditioning treatments were: control (conventional mowing-conditioning), light maceration (one passage through three knurled steel rolls), medium maceration (two passages), and intense maceration (three passages). Concentrations of NDF, ADF, hemicellulose, CP-NDF, and CP-ADF increased linearly (P < 0.001) with the level of maceration. Silage pH, acetic acid, propionic acid, and butyric acid increased, while lactic acid decreased (P < 0.001), with the level of maceration. The effective rumen degradabilities of DM, CP, and NDF, measured with fistulated cows, were not affected (P > 0.10) by the level of mechanical conditioning. Forty-eight male sheep (46.8 ± 6.7 kg BW) were fed a 100% forage diet according to a completely randomized design with a 2 × 4 factorial arrangement of treatments (two storage methods and four levels of conditioning). Under restricted feeding, DM, NDF, ADF, and hemicellulose digestibilities decreased linearly (P < 0.001) with the level of maceration. However, the digestibility of CP-NDF increased with the level of maceration; the effect was more important in hay than in silage (P < 0.001 for the interaction). When silages were fed ad libitum to 24 sheep, daily DMI was 2.31, 2.88, 2.76, and 2.41% of BW and DM digestibility was 60.8, 60.1, 56.2, and 46.7%, for control, light, medium, and intense maceration, respectively (P < 0.01). The results suggest that light maceration increases DM intake while maintaining digestibility of forages fed to sheep. Because of humid conditions and potential soil contamination due to multiple windrow pickup, intense maceration caused severe nutrient loss, which might be avoided under dry field wilting and good storage conditions. Key words: Alfalfa, hay, silage, digestion, degradability, intake

Milk yield and composition of dairy cows fed concentrate based on high moisture wheat or high moisture corn

Thirty-six Ayrshire cows were assigned to 18 pairs and were blocked within parity (5 pairs of primiparous heifers and 13 pairs of multiparous cows); pairs had similar calving dates. The study, which was conducted over 3 yr, was designed to determine the effects of high moisture grain on milk yield and composition and to determine in vitro DM digestibility and ruminal degradabilities of DM, N, and starch of high moisture grains. Treatment diets consisted of isonitrogenous and isoenergetic concentrates that were based on high moisture wheat or high moisture corn. Both groups were fed a mixture of grass silage, grass hay, protein supplement, and a vitamin and mineral mix for ad libitum intake. Treatment diets were fed from wk 4 to 29 and from wk 4 to 37 of lactation for cows in first and second lactations, respectively. There was no interaction between treatment diet and year of lactation. Cows fed high moisture wheat had higher 4% FCM than did cows fed high moisture corn. Milk composition was similar for the two treatment diets. Ruminal degradabilities of DM and starch were higher for high moisture wheat than for high moisture corn. In vitro DM digestibility was higher for high moisture wheat (90.5%) than for high moisture corn (71.6%). This greater digestibility contributed to the higher milk yield of dairy cows fed high moisture wheat.

Effects of flaxseed supplementation on endometrial expression of ISG17 and intrauterine prostaglandin concentrations in primiparous dairy cows submitted to GnRH-based synchronized ovulation

The objective of the experiment was to determine the effects of feeding whole flaxseed on ovarian function and uterine concentration of prostaglandins on the 17th day post-ovulation. Fortyeight primiparous Holstein cows averaging 550 kg of body weight (BW) were allotted at 2 wk postpartum to two groups of 24 animals: a control diet with no added fat (CON) or a diet with 9% whole flaxseed (FLA). At 6 wk postpartum cows were subjected to a Presynch-Ovsynch protocol with and without artificial insemination on day 0. Real-time transrectal ultrasonography and plasma progesterone concentrations were used to evaluate ovarian function. On day 17, uterine flushings and biopsies of uterine endometrium were collected. Synchronized ovulation rates based on low and high plasma progesterone concentrations on days 0 and 7, respectively, were the same for cows fed CON and those fed FLA (87.5 vs. 87.5%). The 13,14-dihydro-15-keto-PGF2α (PGFM) to prostaglandin E metabolite (PGEM) ratio in uterine flush was significantly higher for non-inseminated cows fed CON (32.0) than for non-inseminated cows fed FLA (17.5) and there was no difference between pregnant cows fed CON (12.2) and those fed FLA (12.0). Feeding flaxseed before breeding may contribute to increased fertility by improving uterine conditions for embryo survival. Key words: Flaxseed, dairy cattle, ovarian function, prostaglandins

Effects of mechanical treatment of whole canola seeds on carcass composition and blood lipids of lambs fed grass silage

Thirty-three lambs (25.2 ± 2.7 kg BW) were used to study if mechanical treatment of canola seeds can exert an effect on carcass quality, blood lipids, and fatty acid profile of depot fat. All lambs received a basal diet of 179 g d−1 of a 16% CP commercial concentrate and grass silage fed ad libitum. The basal diet was supplemented with the following dietary treatments (dry matter basis): C, a control supplement supplying 182 g of a mixture of 66% canola meal and 34% canola oil; WCS, 187 g of whole canola seeds; RCS, 188 g of rolled canola seeds; and GCS, 189 g of ground canola seeds. Dressing percentage was higher (P < 0.05) for diet C (45.6%) than for WCS (42.5%) and RCS (41.9%). The highest and lowest carcass grades were obtained with diets C and RCS, respectively (P < 0.05). Blood lipid concentrations increased as the lambs grew older (P < 0.01). Lambs fed the GCS diet had lower plasma concentrations of total cholesterol and high density lipoprotein cholesterol than lambs fed the WCS or RCS diets (P < 0.05). Kidney fat of lambs on the C diet contained more trans -C18:1 and less C18:0 compared with the other diets (P < 0.01). The utilization of untreated or rolled canola seeds as protein and fat supplements decreased carcass quality, increased blood triglycerides and changed fatty acid composition of depot fat. Key words: Canola seeds, lambs, carcass composition, blood lipid

Ruminal degradability of alfalfa and corn after processing or maceration

The effects of mechanical treatment on ruminal degradability of alfalfa and corn were determined in three experiments using nylon bags incubated in the rumen of two fistulated dry cows. The first experiment was a 2 × 2 × 2 factorial design applied to chopped alfalfa at two levels of mechanical treatment (processing with two corrugated rolls in a forage harvester or no processing), two throughput rates (medium or high) and two moisture contents (after a 4-h or a 24-h field wilting period prior to processing). The second experiment was a 2 × 2 factorial design applied to chopped corn at two levels of mechanical treatment (processed or not) and two throughput rates (medium or high). In these two experiments, forages were immediately frozen (not fermented) for later degradability measurements. In the third experiment, alfalfa was mowed either with a conventional mower-windrower or an experimental mower-macerator with three corrugated rolls. After 40 h of field wilting, alfalfa was dehydrated and processed into pellets. In the first experiment (chopped and frozen alfalfa), throughput, processing and wilting period had no effect (P > 0.05) on the effective degradability of DM, CP, NDF and ADF. In the second experiment, DM degradability of chopped corn decreased with an increased throughput (46.4% vs. 43.7%) but increased with processing (43.9% vs. 46.2%). Processing also increased CP degradability of corn. In the third experiment, maceration with subsequent field wilting during 40 h and dehydration produced alfalfa pellets with a higher degradability of DM (56.0% vs. 50.4%) and of NDF (27.1% vs. 17.3%) than pellets from non-macerated alfalfa. These results suggest that the increase in ruminal degradability is greater with alfalfa macerated and wilted in the field (exp. 3) than with alfalfa frozen immediately after harvesting and processing (exp. 1). Maceration probably reduced the loss of nutrients by decreasing field respiration. Processing of corn may have increased the ruminal degradability because of increased kernel breakage that facilitated starch digestion. Key words: Maceration, crop processing, ruminal degradability, alfalfa, corn

Estimation of intake and digestibility of silage by beef steers using a controlled release capsule of n-alkanes

Twelve beef steers were fed a grass-legume silage either ad libitum or at 70% of ad libitum feeding. Intake and digestibility were measured directly or predicted using the alkane ratio technique. The C32 and C36 alkanes were delivered via a controlled release capsule (CRC) in the rumen. Level of feeding had no effect on digestibility (P > 0.05) but dry matter (DM) intake tended to be greater for steers fed ad libitum (P = 0.08). The release of alkanes from the CRC was erratic and 20% greater than expected. This influenced the exogenous to endogenous alkane ratios. Estimates of intake were therefore derived using both the expected and actual (determined from total collection of feces and their alkane analysis) exogenous alkane release rates. Estimated intakes based on the manufacturers’ release rate were underestimated and associated with high standard errors. For cattle fed restricted silage, estimated intakes obtained with C31:C32, C33:C32 and C33:C36 alkane pairs and using actual measured release rates of exogenous markers were associated with lower standard errors and averaged 87, 102 and 103% of actual values, respectively. For ad libitum-fed cattle the corresponding values were 81, 96 and 96% of actual values. There was no significant difference between actual and estimated DM intake when the C33:C32 and C36:C32 alkane pairs were used. The precision of intake estimates using manufacturers release rates for exogenous alkanes was poor, as evidenced by significant discrepancies (P < 0.05 for four of six estimates) between observed and predicted values averaging 2.26 kg or 30% of DM intake. However, when measured exogenous alkane release rates were used, standard errors were reduced and discrepancies for estimates using C33:C32 and C33:C326 were only 0.4 kg or 6% of DM intake. Fecal recovery of C27, C29, C31 and C33 alkanes was 73.4, 92.7, 85.6 and 100%, respectively. Both C29 and C33 gave good estimates of digestibility because of high recovery. Observed and estimated values were not significantly different. It is concluded that exogenous alkane release from CRCs was not satisfactorily consistent. Reliable estimates of intake could only be made if actual release rate was known. Endogenous alkanes can be used for determination of digestibility, provided fecal recovery is known. Key words: Beef, silage, alkane, intake, digestibility

Production of ewes rearing twin or triplet lambs fed grass silage with a commercial concentrate or a mixture of beet pulp and soybean meal

Forty multiparous Outaouais ewes were used to investigate the effects of number of suckling lambs (2 versus 3) and type of feed supplement in grass silage-based diets on ewe and lamb performance. Treatments were arranged in a 2 × 2 factorial design. Isonitrogenous and isoenergetic supplements were either a mixture of beet pulp and soybean meal (BP) or a commercial concentrate (CO). Dietary treatments continued from 28 d prepartum until 42 d postpartum. Milk yield was measured weekly. Dietary treatments and number of suckling lambs had no effect (P > 0.10) on DM intake. Feeding BP resulted in similar milk yield for ewes nursing twin (TW) and triplet (TR) lambs, and feeding CO resulted in higher milk yield for ewes nursing TW compared to those nursing TR; this resulted in a significant interaction (P = 0.08) between diet and the number of suckling lambs. Dietary treatments and number of suckling lambs had no effect (P > 0.10) on milk composition. Loss of body weight was greater (P < 0.01) for ewes nursing TR than for those nursing TW, while there was no difference (P > 0.10) between ewes fed BP and those fed CO. Body weight at birth and on day 42, and ADG of TW were greater (P < 0.01) than those of TR, but type of supplement had no effect on lamb performance. Intake of DM was below requirements of ewes nursing TW. These data suggest that DM intake is not responsible for all differences observed in milk yield. Factors such as greater body weight loss could have contributed to increased milk yield. Feeding BP compared to CO may have contributed to maintain similar milk yield for ewes nursing TW and TR, but lamb growth was limited by milk yield as less milk was available per lamb for TR compared to TW. Key words: Ewes, lambs, lactation, beet pulp

Effect of feeding different sources of fat during gestation and lactation on reproduction of beef cows and calf performance

Experiment 1: Over a 2-yr period, a total of 231 Angus crossbred cows were assigned randomly to one of three gestation diets to evaluate the effects of fat sources on birth weight, weaning weight and average daily gain of calves, calf condition at birth, calf mortality, body weight of cows, gestation length, calving percentage, and the percentages of retained placenta and dystocia. Isonitrogenous and isoenergetic supplements were based on whole flaxseed (FLA), calcium salts of palm oil (Megalac®, MEG) or no fat (CON). All cows were fed grass silage (90% of ad libitum intake) until 1 mo before calving. Cows were then fed grass silage for ad libitum intake until they were put on pasture. Cows were offered 600 g of supplement per head per day starting 43 d before the first calving for a period averaging 78 d. Diet had no effect on body weight (BW) of cows at calving. Birth weights of calves were similar among treatments. However, calf mortality percentage at birth was almost four times higher (P = 0.03) for cows fed CON compared with those fed FLA and MEG. More than 90% of cows rejected placenta within 12 h of calving and treatment had no effect. Cows fed FLA and CON tended (P ≤ 0.10) to have higher cumulative pregnancy rates (92.9 and 91.9%, respectively) than those fed MEG (76.7%). Experiment 2: From 2000 Jan. 19 to 2000 Sep. 05, 41 heifers received 600 g per head per day of one of the three supplements used in exp. 1 to determine the effect of fat supplementation during pregnancy and breeding. Diet had no effect on calf birth weight, but contrasts indicated that heifers fed MEG tended (P = 0.09) to have a lower pregnancy rate than those fed CON. These data suggest that cows and heifers fed grass silage and/or on pasture would not be deficient in omega 3 fatty acids, thus would not benefit from a supplement rich in omega 3 fatty acids such as flaxseed. However, fat supplementation contributed to lower calf mortality at birth in cows, but not in heifers. Key words: Beef, flaxseed, reproduction, fatty acids

Effect of feeding fermented, ammoniated, condensed whey permeate on intake, digestibility, rumen fermentation, and acid-base balance in sheep

Nine DLS rumen-cannulated wethers (69 kg avg BW) were used to study the effects of dietary supplementation with two types of fermented, ammoniated, condensed whey permeate on performance, rumen physiology and acid-base status in sheep fed high-grain diets. Sheep were fed three isonitrogenous (16% CP) diets according to a triple 3 × 3 Latin square design, with three 21-d periods each. One whey permeate contained ammonium lactate (AL) while the other contained ammonium propionate (AP). Urea was used as a source of NPN in the control diet (C). Diets, offered ad libitum, contained 78% barley and 18% dehydrated alfalfa meal. Dry matter and digestible energy intakes were about 15% higher for diets AL and AP than for diet C (P < 0.05). Dry matter digestibility was not affected by the treatments, whereas organic matter and energy digestibilities tended to be higher for diet AP than for diet AL (P < 0.07). Rumen fermentation was not affected by the treatments. Over a 4-h post-feeding period, sheep fed diet C had higher plasma concentrations of lactate (P < 0.06) and acetate (P < 0.04) but lower levels of plasma propionate (P < 0.06) than sheep fed the AL and AP diets. Plasma propionate 2 h after feeding was higher in sheep fed the AL diet versus the AP diet (P < 0.01). Sheep blood was mildly alkalotic despite the fact that sheep were fed a high-grain diet. The two types of fermented, ammoniated and condensed whey permeate were found to be good sources of NPN. Key words: Whey, rumen fermentation, acid-base balance, sheep

Digestibility and performance of dairy bulls fed corn and grass silages with various sequences and levels of barley

Sixty Canadian Holstein male calves (mean weight 261 kg), previously fed all-concentrate diets, were allocated to one of six different sequences of barley supplementation. Rolled barley was provided in the diet at three levels (0, 17 and 34% on a DM basis) with either grass or corn silages, and fed as a total mixed ration for 91, 77 and 70 d during periods 1,2, and 3, respectively, to ensure consumption of 330 kg of barley per animal for the entire experiment. Barley supplementation in the last period improved average daily gain over the whole experiment by 0.223 kg d−1 (P = 0.0154), and feed efficiency by 55% (P = 0.0062) compared to inclusion of barley in the silage mixtures during the first period. Feed efficiency improved with concentrate supplementation of both silages (P ≤ 0.0001), but the improvement with grass silage was greater than with corn silage (P = 0.0041). Dry matter and energy digestibilities were not affected by feed sequences (P = 0.1025, P = 0.0833, respectively), but they were higher for mixed diets than for pure silage (P = 0.0186, P = 0.0218, respectively). Dry matter intake was 0.81 kg d−1 higher (P ≤ 0.0001) when concentrate was added to the diet. These results suggest that energy feeds such as barley are more efficiently used in the last part of growth. This experiment demonstrates the feasibility of switching grain-fed calves to roughage diets. Key words: Barley, dairy bulls, energy distribution, corn silage, grass silage