Effects of Flaxseed on Protein Requirements and N Excretion of Dairy Cows Fed Diets with Two Protein Concentrations

Thirty-eight midlactating Holstein cows averaging 597 kg of body weight (SD = 59) were used to determine the effects of dietary flaxseed on protein requirement and N excretion in urine and feces. Milk yield and composition, intake, and digestibility were also determined. Cows were allotted from wk 20 to 30 of lactation to 1 of 4 TMR containing 1) no flaxseed (control) and 16% protein (MPC), 2) whole flaxseed and 16% protein (MPF), 3) no flaxseed (control) and 18% protein (HPC), and 4) whole flaxseed and 18% protein (HPF). Cows fed high protein diets had greater feed intake than those fed medium protein diets (20.2 vs. 18.4 kg/d), and cows fed no flaxseed had greater dry matter intake than those fed flaxseed (20.1 vs. 18.5 kg/d). Milk yield was lower for cows fed MPF (20.3 kg/d) than for those fed HPC (24.4 kg/d), HPF (24.9 kg/d), or MPC (24.0 kg/d). Milk protein and lactose concentrations were similar for cows fed MPC and HPC, but flaxseed decreased milk protein concentration in cows fed MPF or HPF compared with cows fed the control diets. Milk fat concentration was similar in cows fed diets with or without flaxseed, but it was decreased by higher protein concentration. Digestibility was generally reduced when diets contained flaxseed and lower protein concentration. Dietary protein had no effect while dietary flaxseed increased fecal N excretion. Retention of N was lower in cows fed flaxseed compared with cows fed the control diets. Feeding flaxseed decreased milk concentrations of short- and medium-chain fatty acids and increased those of long-chain fatty acids. Flaxseed had no effect on the dietary requirement of N by midlactating dairy cows.

Feeding Micronized and Extruded Flaxseed to Dairy Cows: Effects on Blood Parameters and Milk Fatty Acid Composition

Four lactating Holstein cows fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design to determine the effects of feeding micronized and extruded flaxseed on milk composition and blood profile in late lactation. Four diets were formulated: a control (C) diet with no flaxseed, a raw flaxseed (RF) diet, a micronized flaxseed (MF) diet, and an extruded flaxseed (EF) diet. Flaxseed diets contained 12.6% flax-seed (dry matter basis). Experimental periods consisted of 21 d of diet adaptation and 7 d of data collection. Feeding flaxseed reduced milk yield and energy-corrected milk by 1.8 and 1.4 kg/d, respectively. Yields of milk protein and casein were also lower for cows fed flaxseed diets than for those fed the C diet. Milk yield (1.6 kg/d) and milk fat percentage (0.4 percentage unit) were lower for cows fed EF than those fed MF. Plasma cholesterol and nonesterified fatty acid concentrations were higher for cows fed flaxseed diets relative to those fed the C diet. Flaxseed supplementation decreased plasma concentrations of medium-chain (MCFA) and saturated (SFA) fatty acids and increased concentrations of long-chain (LCFA) and monounsaturated fatty acids. Feeding flaxseed reduced the concentrations of short-chain fatty acids (SCFA), MCFA, and SFA in milk fat. Consequently, concentrations of LCFA and unsaturated fatty acids were higher for cows fed flaxseed diets than for those fed the C diet. Flaxseed supplementation increased average concentrations of C(18:3) and conjugated linoleic acid by 152 and 68%, respectively. Micronization increased C(18:3) level, and extrusion reduced concentrations of SCFA and SFA in milk. It was concluded that feeding raw or heated flaxseed to dairy cows alters blood and milk fatty acid composition. Feeding extruded flaxseed relative to raw or micronized flaxseed had negative effects on milk yield and milk composition.

Feeding micronized and extruded flaxseed to dairy cows: Effects on digestion and ruminal biohydrogenation of long-chain fatty acids

Four lactating Holstein cows fitted with ruminal and duodenal cannulae were used in a 4 × 4 Latin square study to determine the effects of feeding micronized and extruded flaxseed on ruminal biohydrogenation (BH) and digestibility of fatty acids (FA) in the gastrointestinal tract. Four diets were formulated: a control diet with no flaxseed (C); a raw flaxseed diet (RF); a micronized flaxseed diet (MF); and an extruded flaxseed diet (EF). Flaxseed diets contained 126 g kg-1 flaxseed (dry matter basis). Experimental periods (n = 4) consisted of 21 d of diet adaptation and 7 d of data collection. Flaxseed supplementation increased (P < 0.05) intake of individual long-chain FA, reduced (P < 0.05) ruminal BH of total unsaturated C18, and increased (P < 0.05) duodenal flow of individual long-chain FA except for C18:2. Feeding flaxseed increased (P < 0.05) post-ruminal digestibility of C18:1, C18:2, and C18:3 and total tract digestibility of C16:0, C18:2, C18:3, and of total long-chain FA. Heat treatment had no effect on ruminal BH, duodenal flow and digestibility of unsaturated FA. Ruminal BH of C18:3 was higher (P < 0.05), while the duodenal flow of C18:3 was lower (P < 0.05) for cows fed EF than for those fed MF. Intake and duodenal flow of C16:0 were higher (P < 0.05) for cows fed MF relative to those fed EF. It was concluded that inclusion of flaxseed in dairy cow diets increased duodenal flow of polyunsaturated FA. However, heat treatments were not effective in protecting unsaturated FA from ruminal BH. Key words: Flaxseed, ruminal biohydrogenation, fatty acid, heat treatment

Influence of parturition and diets enriched in n-3 or n-6 polyunsaturated fatty acids on immune response of dairy cows during the transition period

The objectives of this study were to evaluate the functional properties of immunocompetent cells in dairy cows fed diets enriched in n-3 or n-6 polyunsaturated fatty acids during the transition period. Six weeks before calving, 21 primiparous and 27 multiparous pregnant Holstein dairy cows were randomly allotted to 1 of 3 dietary fat treatments: calcium salts of palm oil (Megalac), micronized soybeans, or whole flaxseed, which are, respectively, rich in saturated, n-6, or n-3 fatty acids. On wk 6 and 3 before parturition, cows received a subcutaneous injection of ovalbumin to measure the antibody response in colostrum and serum. Colostrum samples were collected at the first milking after calving, and blood samples were taken 6, 3, and 1 wk before the expected calving date and 1, 3, and 6 wk after calving. Blood mononuclear cells were cultured to evaluate the proliferative response to concanavalin A and the in vitro productions of interferon-gamma, tumor necrosis factor-alpha, nitric oxide, and prostaglandin E2. The serum antibody response to ovalbumin was unaffected by dietary fatty acids, but the response was lower in primiparous cows than in multiparous cows. A significant diet x parity interaction indicated that colostral antibody level against ovalbumin was significantly higher in multiparous cows fed soybeans than in those fed flaxseed or Megalac; there was no difference among treatments for primiparous cows. The lymphocyte response to concanavalin A was lower in cows fed soybeans than in those receiving flaxseed or Megalac when the cells were incubated with autologous serum. The proliferative response of mononuclear cells incubated with autologous serum was suppressed in the 1st wk after calving in both primiparous and multiparous cows, and multiparous cows showed a higher response than primiparous cows throughout the experiment. There was a significant interaction between parity and diet as a result of a greater production of interferon-gamma by mononuclear cells incubated with autologous serum in multiparous cows than in primiparous cows fed flaxseed; there was no difference among cows fed the other diets. Interferon-gamma production was reduced around calving while the inverse was observed for productions of nitric oxide and tumor necrosis factor-alpha. Productions of nitric oxide, prostaglandin E2, and tumor necrosis factor-gamma were greater in primiparous cows than in multiparous cows. In conclusion, functional properties of lymphocytes and monocyte/macrophage lineage of dairy cows during the transition period are modulated by parturition and the composition of polyunsaturated fatty acids in the diet.

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

Effects of Feeding Micronized and Extruded Flaxseed on Ruminal Fermentation and Nutrient Utilization by Dairy Cows

Four lactating Holstein cows with ruminal and duo-denal cannulas were used in a 4 x 4 latin square design to determine the effects of feeding heat-treated flaxseed on ruminal fermentation and site and extent of nutrient utilization. Four diets were formulated: a control diet with no flaxseed, a raw flaxseed diet (RF), a micronized flaxseed diet (MF), and an extruded flaxseed diet (EF). Flaxseed diets contained 12.6% flaxseed (dry matter [DM] basis). Ruminal pH, NH3 N, and total concentration of volatile fatty acids were not affected by dietary treatments. However, feeding flaxseed decreased the molar proportion of acetate and increased that of propionate. Flaxseed supplementation had no effect on ruminal digestion of DM, organic matter (OM), neutral detergent fiber (NDF), crude protein (CP), fatty acids (FA), and gross energy. However, ruminal digestion of acid detergent fiber (ADF) was lower for cows fed the flaxseed diets than for cows fed the control diet. Feeding flaxseed tended to increase post-ruminal and total tract digestibilities of DM, OM, NDF, and gross energy. Feeding heat-treated flaxseed diets relative to RF had no effect on ruminal, post-ruminal, and total tract nutrient digestibilities. Cows fed EF had higher ruminal and lower post-ruminal digestibilities of DM, OM, ADF, CP, and FA than cows fed MF. However, total tract digestibilities were similar for the 2 heat treatments. It was concluded that flaxseed supplementation improved total tract nutrient utilization with no adverse effects on ruminal fermentation. Extrusion failed to protect flaxseed from ruminal digestion. However, micronization can be used to increase the ruminal undegraded protein value of flaxseed.

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

Fatty acids in forages. I. Factors affecting concentrations

When forages represent a high proportion of ruminant diets they provide a significant quantity of fatty acids (FA). Effects of growth stage, fertilization, conservation method, growth period, species, and cultivar on forage FA were determined in four experiments. Concentrations of C16:0, C18:2, C18:3, and total FA (TFA) in timothy (Phleum pratense L.) decreased (P < 0.01), respectively, by 15, 16, 31, and 23% between stem elongation and early flowering. Nitrogen fertilization (120 vs. 0 kg N ha-1) caused an increase (P < 0.01) of 18% of C16:0, 12% of C18:2, 40% of C18:3, and 26% of TFA concentrations. Phosphorus was not deficient and P fertilization (45 vs. 0 kg P ha-1) had no significant effect on timothy FA concentrations. Wilting and drying decreased (P < 0.01) timothy C18:2, C18:3, and TFA concentrations. Concentrations of C18:2, C18:3, and TFA were higher in summer regrowth than in spring growth, primarily in orchardgrass (Dactylis glomerata L.) and timothy (P < 0.01). Significant variation for all FA concentrations was observed among 12 species (P < 0.05); on average, the C18:3, C18:2, and C16:0 accounted for 88% of TFA in studied species. Timothy was the only species in which the difference among cultivars was simultaneously significant (P < 0.05) for concentrations of C18:2, C18:3, and TFA. Among the grasses, an annual ryegrass (Lolium multiflorum Lam.) cultivar had the highest C18:3 concentration (20.6 mg g-1 DM) whereas a timothy cultivar had the lowest (7.3 mg g-1 DM) (P < 0.05). Among legumes, a white clover (Trifolium repens L.) cultivar had the highest C18:3 concentration (16.5 mg g-1 DM) whereas an alfalfa (Medicago sativa L.) cultivar had the lowest (6.0 mg g-1 DM) (P < 0.05). Polyunsaturated FA concentrations in forages can be increased by harvesting timothy at an early stage of development and as fresh grass, by increasing N fertilization of timothy, and by choosing species with higher FA concentrations such as white clover and annual ryegrass. Key words: Fatty acids, forages, species, cultivar, growth stage, conservation methods

Fatty acids in forages. II. In vitro ruminal biohydrogenation of linolenic and linoleic acids from timothy

Polyunsaturated fatty acids from forages are hydrogenated in the rumen and this biohydrogenation depends on several factors. The objective of this study was to determine and compare in vitro ruminal biohydrogenation of linolenic (C18:3) and linoleic (C18:2) acids in timothy harvested from different growth stages, produced with or without fertilization, or conserved by different methods. In exp. 1, timothy was grown with (120 kg ha-1) and without N and harvested at four growth stages. In exp. 2, harvested timothy was conserved as fresh grass, wilted grass, dry hay, haylage, and silage, some with additives: haylage with lactic acid bateria (LAB), haylage with formic acid, silage with LAB, and silage with formic acid. Samples were incubated with rumen fluid in three trials to compare: (1) samples from exp. 1; (2) the five basic conserving methods of exp. 2, and; (3) how the silage additives affected biohydrogenation of C18:3 and C18:2. Effective disappearances and ruminal bypass of C18:3 and C18:2 were fastest in timothy harvested at stem elongation but slowed linearly with increasing maturity (P < 0.01). Although N fertilization increased (P < 0.01) the effective disappearance and bypass of C18:3 and the bypass of C18:2, it did not affect their rate of disappearance. These last rates were not affected by maturity, but were faster in haylage and silage than in hay (P < 0.01). Ruminal bypass of C18:3 was greater in fresh grass, wilted grass, and dry hay than in haylage and silage (P < 0.01). Additions of formic acid and LAB to haylage and silage had no significant effect on C18:3 and C18:2 disappearances and bypass. To maximize the amount of C18:3 that bypasses ruminal biohydrogenation timothy should be fertilized with N, harvested at an early growth stage, and conserved as dry hay. Key words: Biohydrogenation, fatty acids, N fertilization, maturity, conservation methods, timothy

Immune response of postpartum dairy cows fed flaxseed

Thirty Holstein cows were allotted at calving to 10 groups of three cows blocked for similar calving dates to determine the effects of dietary fatty acids on functional properties of immunocompetent cells in early lactation and at breeding. Cows were assigned at calving to one of three isonitrogenous, isoenergetic, and isolipidic supplements based on either calcium salts of palm oil, Megalac, micronized soybeans, or whole flaxseed. On the day of AI and 20 d later, cows were injected with ovalbumin to measure the antibody response. Blood samples were taken at different times after calving (d 5, 21, 42, and 105) and after AI (d 0, 10, 20, and 40) for quantification of serum progesterone, fatty acids, and prostaglandin E2 concentrations. Isolated peripheral blood mononuclear cells were cultured to evaluate the proliferative response to concanavalin A and in vitro productions of interferon-gamma and prostaglandin E2. In general, feeding flaxseed increased serum omega-3 fatty acids concentration compared with feeding Megalac or soybeans, which decreased the omega-6 to omega-3 fatty acids ratio. There was a significant diet x day interaction for the proliferative response of mononuclear cells after calving and AI, indicating that cell responses from cows fed flaxseed were transiently reduced compared with those fed Megalac and soybeans. Moreover, during the breeding period, serum progesterone concentration was significantly greater in cows fed flaxseed compared with those fed Megalac, whereas serum concentration of prostaglandin E2 was significantly lower in cows fed flaxseed than in those fed Megalac or soybeans. Dietary treatments had no effect on the antibody response to ovalbumin and on in vitro productions of interferon-gamma and prostaglandin E2. However, interferon-gamma and prostaglandin E2 were impaired in the first 3 wk after parturition regardless of dietary treatment. These results suggest that changes in fatty acids, progesterone, and prostaglandins E2 concentrations in serum due to dietary treatment and physiological status influenced systemic immunity as shown by reduced proliferative response. However, other mechanisms must be considered and are discussed to explain dietary effect on lymphocyte proliferative response to mitogenic stimulation and other immune functions.

Digestion, milk production, milk composition, and blood composition of dairy cows fed formaldehyde treated flaxseed or sunflower seed

Forty midlactation Holstein cows averaging 635 kg of body weight (SE = 8) were allotted at wk 25 of lactation to ten groups of four cows blocked for similar calving dates to determine the effects of formaldehyde treatment of flaxseed and sunflower seed on fatty acid composition of blood and milk, milk yield, feed intake, and apparent digestibility. Cows were fed a total mixed diet based on grass silage and supplements for ad libitum intake over a 10-wk period. Cows within each block were assigned to one of the four isonitrogenous supplements based on either untreated whole flaxseed, formaldehyde-treated whole flaxseed, untreated whole sunflower seed, or formaldehyde-treated whole sunflower seed. Cows fed whole flaxseed compared with sunflower seed maintained greater dry matter (DM) intake (20.3 vs. 18.9 kg/d). Intake of DM, expressed as a percentage of body weight, was increased by adding formaldehyde to oilseeds (3.24 vs. 2.98%). Milk production was similar for cows fed flaxseed and those fed sunflower. Formaldehyde treatment of flaxseed and sunflower seed increased milk production by an average of 2.65 kg/d. Efficiency of fat-corrected milk yield per kilogram of DM intake was increased by formaldehyde treatment (1.31 vs. 1.21), and it was greater with sunflower seed than with flaxseed (1.33 vs.1.21). Protein concentration in milk was greater for cows fed flaxseed (3.38%) compared with those fed sunflower seed (3.21%) and formaldehyde had no effect. Apparent digestibility of DM was not affected by type of seed but it was greater for cows fed formaldehyde-treated seeds. Cows fed formaldehyde-treated flaxseed had the greatest apparent digestibilities of acid detergent and neutral detergent fiber compared with those fed the other diets. Apparent digestibilities of fatty acids were greater for sunflower seed than for flaxseed-based diets. In general, formaldehyde treatment had limited effect on milk fatty acid composition, suggesting that formaldehyde was not very effective in protecting polyunsaturated fatty acids against ruminal biohydrogenation. Feeding flaxseed resulted in the lowest omega 6 to omega 3 fatty acid ratio. The data suggest that both flaxseed and sunflower seed are acceptable fat sources for midlactating cows and that flaxseed increases milk protein percentage compared to sunflower seed.

Milk production and composition, ovarian function, and prostaglandin secretion of dairy cows fed omega-3 fats

Four multiparous Holstein cows were used in a 4 x 4 Latin square experiment to study the effects of fat sources rich in omega-3 fatty acids on milk production and composition, follicular development, and prostaglandin secretion. All cows were fed a total mixed diet containing 60% grass silage and 40% concentrate. The four treatments were concentrates based either on Megalac, formaldehyde-treated whole linseed, a mixture (50:50, oil basis) of fish oil and formaldehyde-treated whole linseed, or no fat source in the concentrate but with 500 g per day of linseed oil being infused into the duodenum. Feed intakes and milk yield were similar among treatments. In general, the lowest digestibility was observed for the formaldehyde-treated whole linseed treatment. Feeding fish oil decreased milk fat and protein percentages. Alpha-linolenic acid increased from 1.0 to 13.9% of milk fatty acids with linseed oil infusion. This confirms the high potential to incorporate alpha-linolenic acid into milk, and suggests that the formaldehyde treatment had little effect to limit biohydrogenation in the rumen. Increasing the supply of alpha-linolenic acid to these cows did not result in an increase in the concentration of eicosapentaenoic acid in milk. Levels of 13,14-dihydro-15-keto-PGF2alpha in plasma were higher for cows receiving formaldehyde-treated linseed and fish oil. Increases in this metabolite in response to oxytocin challenge, tended to be lower for cows given linseed either as sole oil supplement in the diet or as a duodenal infusion of linseed oil. Follicle dynamics were similar among treatments. Larger corpora lutea (CL) were found with cows that received high levels of omega-3 fatty acids through the diet as formaldehyde-treated linseed or as a mixture of formaldehyde-treated linseed and fish oil, although CL were smaller when cows were infused with linseed oil into the duodenum. These results suggest that the improvement in gestation rate that was observed when feeding increased levels of alpha-linolenic acid in earlier work may partly result from lower levels of production of the dienoic prostaglandin PGF2alpha.

Milk production, milk composition, and reproductive function of dairy cows fed different fats

Thirty-five non-gestating multiparous Holstein cows averaging 571 kg of BW (SE = 8) were allotted at 9 wk postpartum to one of two dietary fat supplements based on either Megalac® (Volac Ltd., Roston, Hertfordshire, UK) and solvent extracted flaxseed meal (MEGA) or whole flaxseed treated with formaldehyde (FLAX) to determine the effects on milk production and composition, follicular development, gestation rate, and fatty acid (FA) composition of blood. Cows were fed a total mixed diet based on ryegrass silage and fat supplements for ad libitum intake. The experiment was carried out between weeks 9 and 19 of lactation. Dry matter (DM) intake and change in body weight were similar for cows fed MEGA and FLAX. Milk production was higher for cows fed MEGA than for those fed FLAX (19.8 vs. 18.6 kg d–1) as was 4% fat-corrected milk yield (22.9 vs. 20.2 kg d–1). Increased fat mobilization could have contributed to increased milk yield when cows were fed MEGA compared with when they were fed FLAX as plasma concentrations of non-esterified FA and cholesterol increased more from weeks 9 to 19 of lactation for cows fed MEGA. Milk fat percentage tended (P = 0.06) to be greater for cows fed MEGA (4.62%) compared with those fed FLAX (4.37%). Milk protein percentage was higher for cows fed FLAX (3.09%) than for those fed MEGA (2.95%), indicating that formaldehyde protection of flaxseed was adequate to partly prevent ruminal degradability of protein in the seed. Milk fatty acid concentrations of C8:0, C10:0, C12:0, C14:0, C14:1, C18:0, C18:3, and C20:5 were higher for cows fed FLAX than for those fed MEGA while the inverse was observed for C16:0, C16:1, C18:1, and C18:2. Cows fed FLAX had lower blood concentrations of C16:0 than those fed MEGA. There was a significant interaction (P < 0.05) between week and diet for C18:0 and C18:2 with a decrease in C18:0 blood concentration for cows fed MEGA and an increase for those fed FLAX between weeks 9 and 19, while the inverse was observed for C18:2. Blood concentrations of C18:1 were similar for both treatments. Conception rate was significantly lower for cows fed MEGA (50.0%) compared to those fed FLAX (87.5%). Diet had no effect on the size of the largest and second largest follicles, or on the difference between the diameter of the largest and second largest follicles. The number of class 1 (1.09 vs. 0.86), 2 (1.33 vs. 0.86), and 3 (1.28 vs. 0.98) follicles was similar for MEGA and FLAX although the total number (3.70 vs. 2.70) of follicles tended (P = 0.09) to be greater for cows fed MEGA than for those fed FLAX. These data suggest that dietary FA have an effect on gestation rate, but this could not be explained by differences in follicle dynamics or number. However, additional trials with greater numbers of animals are needed to confirm the reproductive results. Key words: Dairy, flaxseed, milk production, reproduction, fatty acids

Short communication: effect of tannic acid on composition and ruminal degradability of bermudagrass and alfalfa silages

We measured the effects of the addition of tannic acid on chemical composition and crude protein (CP) ruminal degradability of bermudagrass, cv. coast cross (Cynodon dactylon L.) and alfalfa (Medicago sativa L.) silages with nylon bags incubated in the rumen of two fistulated lactating cows. Silage pH was greater for alfalfa than for bermudagrass. The addition of tannic acid had no effect on silage pH. Ammonia N was greater in alfalfa than in bermudagrass silage. Treated and control silages had similar ammonia N concentrations. The percentage of CP that was solubilized at time 0 was lower for alfalfa than for bermudagrass silage. The addition of tannic acid decreased the portion of CP solubilized at time 0 and increased the potentially degradable fraction of CP. The potentially degradable fraction of CP was greater for alfalfa than for bermudagrass. There was an interaction of species and treatment; the disappearance rate of CP increased with tannic acid treatment of alfalfa but decreased with acid treatment of bermudagrass. The effective degradability of CP was similar for control and treated alfalfa but lower for treated than for control bermudagrass. Tannic acid treatment is effective in decreasing the rapidly soluble fraction of alfalfa and bermudagrass silages, which could be beneficial to the animal because it would decrease the excess of N in the rumen after feeding. Tannic acid treatment decreased CP degradability of bermudagrass silage but had no effect on alfalfa silage, suggesting that tannic acid concentration required to effectively decrease CP degradability differs among forages.

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

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

Milk yield and composition of dairy cows fed concentrate based on naked oats

A 1.5-yr study was designed to determine the effects of feeding isonitrogenous and isoenergetic concentrates based on naked oats, corn, or a mixture (50: 50 on as-fed basis) of naked oats and corn on milk yield and composition. In vitro dry matter (DM) digestibility and ruminal degradabilities of DM, N, and starch of naked oats were compared with those of covered oats. Twenty-seven multiparous Holstein cows were blocked by similar calving date and assigned to 9 replicates. All cows were fed a mixture of grass silage, protein supplement, concentrate, and a vitamin and mineral mix for ad libitum intake. Treatment diets were fed from 3 to 36 wk of lactation. Milk yield and composition, yield of 4% fat-corrected milk, and yield of protein and fat were similar among treatments. Ruminal effective degradabilities of DM were higher for naked oats than for covered oats, but the ruminal degradabilities of crude protein and starch were similar. The rapidly degradable fractions of DM, crude protein, and starch were greater for naked than covered oats; the potentially degradable fractions were less. In vitro DM digestibility of naked oats was higher than was that of covered oats. Naked oats may be a good alternative to corn for milk yield.

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

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

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 raw or extruded peas

Primiparous (n = 9) and multiparous (n = 18) Holstein cows averaging 584 +/- 15 kg of body weight (mean +/- SE) were allotted at 2 wk postpartum to nine groups (3 primiparous and 6 multiparous) of 3 cows each to determine the effects of pea extrusion on ruminal degradability and milk production. Cows were fed a total mixed diet based on timothy silage and concentrate for ad libitum intake. The experiment was carried out between wk 4 and 15 of lactation. Cows within each group were assigned randomly to isonitrogenous and isoenergetic concentrates based on corn plus soybean meal, raw peas, or extruded peas. Extrusion of peas increased the ruminal degradability of starch but had no effect on the ruminal degradability of crude protein. Cows fed extruded peas had higher dry matter intakes and plasma urea N concentrations than did those fed soybean meal; no differences were detected between cows fed extruded and raw peas. Production of 4% fat-corrected milk and milk composition generally were similar for cows fed the various diets. Digestibilities of dry matter and N were higher for cows fed extruded peas than for cows fed soybean meal or raw peas. These data suggest that peas can substitute for soybean meal as the protein source in diets of early lactation cows without adverse effects on production and that, in this study, the extrusion of peas had no beneficial effect on milk production.

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

Performance of growing lambs fed two levels of concentrate with conventional or macerated timothy hay

Thirty-two Outaouais male lambs were used in a 2 x 2 factorial design to compare growth and carcass characteristics of lambs fed conventional and macerated hay at two levels of concentrate. Timothy hay was harvested with either a prototype mower-macerator or a conventional mower-conditioner. Hays offered for ad libitum intake were fed with isonitrogenous supplements containing either 400 g of commercial concentrate or a mixture of 100 g of commercial concentrate and 158 g of canola meal. Lambs were fed from an initial weight of 22 kg to a slaughter weight of 43 kg. Feeding the highest level of concentrate tended to decrease hay intake but increased DMI and ADG. Feeding macerated hay had no effect on DMI, digestibility, ADG, and gain:feed. There was an interaction (P < .08) between type of conditioning and feeding level of concentrate for carcass weight, dressing percentage, and muscular conformation of hind leg roast. In general, the highest values were obtained for lambs fed the higher level of concentrate. Efficiency of ME utilization for gain was similar among treatments. These data suggest that the benefits of macerated timothy hay and higher amounts of concentrate on carcass quality are additive.

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.

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