Milk yield, milk composition, and hepatic lipid metabolism in transition dairy cows fed flaxseed or linola.

The response of transition dairy cows to dietary supplementation with fat sources of various fatty acid profiles could affect hepatic fat metabolism differently. Twenty-eight Holstein cows were blocked for similar calving date 4wk before expected parturition to compare the effects of feeding sources of n-3 and n-6 fatty acids on milk production and composition, plasma metabolites, and liver parameters. Cows within each block were assigned to 1 of 3 isonitrogenous and isoenergetic diets: control with a source of calcium salts of palm oil (MEG; 1.1 and 2.6% of the dry matter in prepartum and postpartum diets, respectively); n-3 fatty acids supplied as whole flaxseed (WFL; 4.8 and 7.7% of the dry matter in prepartum and postpartum diets, respectively); and n-6 fatty acids supplied as whole linola (WLO; 4.8 and 7.7% of the dry matter in prepartum and postpartum diets, respectively). Diets were fed until wk 14 of lactation. Contrasts of WFL versus WLO and polyunsaturated fatty acids versus MEG were compared. Cows fed polyunsaturated fatty acids increased dry matter intake over time at a greater extent than those fed MEG, which resulted in enhanced energy balance. Cows fed MEG produced more milk compared with those fed polyunsaturated fatty acids, and there was no difference between those fed WFL and WLO. We found no effect on body condition score and body weight. Plasma concentrations of glucose, fatty acids, and BHB were similar among diets. There was no effect of diet on concentration of glycogen and activities of superoxide dismutase and glutathione peroxidase in the liver. We observed higher concentrations of hepatic lipids and triacylglycerol in cows fed MEG compared with those fed polyunsaturated fatty acids, and no difference between WFL and WLO. Hepatic catalase activity tended to be higher on wk 4 after calving for cows supplemented with WFL compared with those fed WLO. Feeding linoleic and linolenic acids as unprotected oilseeds increased dry matter intake over time at a greater extent for cows fed MEG, improved the energy status, and lowered hepatic lipids and triacylglycerol contents, which may contribute to enhance the health status of transition dairy cows.

Interactions of corn meal or molasses with a soybean-sunflower meal mix or flaxseed meal on production, milk fatty acid composition, and nutrient utilization in dairy cows fed grass hay-based diets.

We investigated the interactions of corn meal or molasses [nonstructural carbohydrate (NSC) supplements] with a soybean-sunflower meal mix or flaxseed meal [rumen-degradable protein (RDP) supplements] on animal production, milk fatty acids profile, and nutrient utilization in dairy cows fed grass hay diets. Eight multiparous and 8 primiparous Jersey cows averaging 135±49d in milk and 386±61kg of body weight in the beginning of the study were randomly assigned to 4 replicated 4×4 Latin squares with a 2×2 factorial arrangement of treatments. Each period lasted 19d with 14d for diet adaptation and 5d for data and sample collection. Cows were fed diets composed of mixed-mostly grass hay plus 1 of the following 4 concentrate blends: (1) corn meal plus a protein mix containing soybean meal and sunflower meal; (2) corn meal plus flaxseed meal; (3) liquid molasses plus a protein mix containing soybean meal and sunflower meal; or (4) liquid molasses plus flaxseed meal. Data were analyzed for main effects of NSC and RDP supplements, and the NSC × RDP supplement interactions. Significant NSC × RDP supplement interactions were observed for milk urea N, milk N efficiency, and the sums of milk saturated, monounsaturated, and polyunsaturated fatty acids. No effect of NSC supplements was observed for nutrient intake and milk yield. However, 4% fat-corrected milk (-0.70kg/d) and energy-corrected milk (-0.60kg/d) were significantly reduced in cows fed liquid molasses due to a trend to decreased concentration of milk fat (-0.17%). Diets with liquid molasses resulted in increased (+35%) concentration and yield of milk enterolactone, indicating that this mammalian lignan can be modulated by supplements with different NSC profiles. Overall, NSC and RDP supplements profoundly changed the milk fatty acid profile, likely because of differences in fatty acids intake, Δ(9)-desaturase indices, and ruminal biohydrogenation pathways. Feeding liquid molasses significantly reduced plasma urea N (-1.2mg/dL), urinary N excretion (-20g/d), and N digestibility (-3.2 percentage units). Flaxseed meal significantly reduced yields of milk (-1.3kg/d), milk fat (-90g/d), and milk lactose (-60g/d), but significantly increased the concentration and yield of milk enterolactone. Further research is needed to elucidate the negative responses of flaxseed meal on yields of milk and milk components.

Effect of prepartal and postpartal dietary fat level on performance and plasma concentration of metabolites in transition dairy cows.

The objective of this study was to determine the effects of 2 levels of dietary fat (low and high) offered during the prepartal and postpartal periods on dry matter intake (DMI), plasma concentration of metabolites, and milk yield and composition. Twenty-four Holstein dry cows were assigned on d 21 relative to expected parturition date to 1 of 4 treatments in a 2×2 factorial arrangement of 2 levels of fat fed during the prepartal period and 2 levels of fat fed during the postpartal period: prepartal low fat and postpartal low fat (LF-LF), prepartal low fat and postpartal high fat (LF-HF), prepartal high fat and postpartal low fat (HF-LF), or prepartal high fat and postpartal high fat (HF-HF). Prepartal and postpartal LF diets contained no fat supplement. Prepartal HF diets contained 1.60% calcium salts of soybean oil. The proportion of calcium salts of soybean oil was increased to 1.70% of DM for the first 21 d of lactation and to 2.27% of DM from d 21 to 56 of lactation in the HF diet. Diets were fed for ad libitum intake from d 21 before calving until d 56 of gestation. Prepartal DMI was lower for cows fed the HF diet compared with those fed the LF diet (12.6 vs. 16.2kg/d). Postpartum, cows fed the HF-HF and HF-LF diets had, respectively, the lowest and highest DMI, although no significant differences existed between HF-LF and LF-LF. Net energy intake was higher for cows fed the postpartal HF diets compared with those fed the LF diets. Prepartal fat level had no effect on net energy intake. Cows offered the prepartal HF diet had higher milk yield when offered the postpartal LF diet compared with those offered the postpartal HF diet and no effect of the postpartal fat level was detected when cows were fed the prepartal LF diet. Milk composition was similar among treatments. Plasma cholesterol concentration postpartum was higher for cows fed the prepartal LF diet than for those fed the prepartal HF diet (5.16 vs. 3.74mmol/L) and postpartal fat level had no effect. Prepartal diet had no significant effect on postpartal plasma triglyceride concentration but the postpartal HF diet increased triglyceride and low-density lipoprotein concentrations compared with the postpartal LF diet. In conclusion, switching from a high to a low fat proportion in the postpartal diet may alleviate the negative effects of a high proportion of fat in the prepartal diet as shown by increased feed intake and milk production during the first 56 d of lactation.

Effects of pistachio by-products on digestibility, milk production, milk fatty acid profile and blood metabolites in Saanen dairy goats.

The objective of this study was to investigate the effects of pistachio by-products (PBP) on nutrient digestibility, blood metabolites and milk fatty acid (FA) profile in Saanen dairy goats. Nine multiparous lactating Saanen goats (on day 90 post-partum, 45 ± 2/kg BW) were randomly assigned to a 3 × 3 Latin square design with three treatment diets: 1) control diet (alfalfa hay based), 2) 32% PBP and 3) 32% PBP + polyethylene glycol (PEG-4000; 1 g/kg dry matter). Each period lasted 21 days, including 14 day for treatment adaptation and 7 day for data collection. Pistachio by-products significantly decreased (p < 0.01) crude protein (CP) digestibility compared with the control diet (64.4% vs. 58.7%), but PEG addition did not differ for CP digestibility of goats fed 32% PBP + PEG and those fed the two other diets. The digestibility of NDF tended (p = 0.06) to decrease for goats fed PBP compared with those fed the control diet. Yields of milk and 4% fat-corrected milk were not affected by dietary treatments. Compared with the control diet, PBP supplementation appreciably changed the proportions of almost all the milk FA measured; the main effects were decreases (p < 0.01) in FA from 8:0 to 16:0 and increases (p < 0.01) proportions of cis-9, trans-11 18:2 and trans-11 18:1, monounsaturated FA, polyunsaturated FA and long-chain FA. The saturated FA, short-chain FA and medium-chain FA proportions were lower (p < 0.01) in goats fed the two PBP supplemented diet than in those fed the control diet and PEG addition led to intermediate proportions of saturated FA, unsaturated and monounsaturated FA. Inclusion of PBP in the diet decreased (p < 0.01) plasma concentrations of glucose and urea nitrogen compared with the control diet. It was concluded that PBP can be used as forage in the diet of dairy goats without interfering with milk yield. Inclusion of 32% PBP in the diet of dairy goats had beneficial effects on milk FA profile but PEG addition to PBP did not contribute to enhance further milk FA profile.

Methane production, nutrient digestion, ruminal fermentation, N balance, and milk production of cows fed timothy silage- or alfalfa silage-based diets.

The objective of this study was to investigate the effects of changing forage source in dairy cow diets from timothy silage (TS) to alfalfa silage (AS) on enteric CH4 emissions, ruminal fermentation characteristics, digestion, milk production, and N balance. Nine ruminally cannulated lactating cows were used in a replicated 3 × 3 Latin square design (32-d period) and fed (ad libitum) a total mixed ration (TMR; forage:concentrate ratio of 60:40, dry matter basis), with the forage portion consisting of either TS (0% AS; 0% AS and 54.4% TS in the TMR), a 50:50 mixture of both silages (50% AS; 27.2% AS and 27.2% TS in the TMR), or AS (100% AS; 54.4% AS and 0% TS in the TMR). Compared with TS, AS contained less (36.9 vs. 52.1%) neutral detergent fiber but more (20.5 vs. 13.6%) crude protein (CP). In sacco 24-h ruminal degradability of organic matter (OM) was higher for AS than for TS (73.5 vs. 66.9%). Replacement of TS with AS in the diet entailed increasing proportions of corn grain and bypass protein supplement at the expense of soybean meal. As the dietary proportion of AS increased, CP and starch concentrations increased, whereas fiber content declined in the TMR. Dry matter intake increased linearly with increasing AS proportions in the diet. Apparent total-tract digestibility of OM and gross energy remained unaffected, whereas CP digestibility increased linearly and that of fiber decreased linearly with increasing inclusion of AS in the diet. The acetate-to-propionate ratio was not affected, whereas ruminal concentration of ammonia (NH3) and molar proportion of branched-chain VFA increased as the proportion of AS in the diet increased. Daily CH4 emissions tended to increase (476, 483, and 491 g/d for cows fed 0% AS, 50% AS, and 100% AS, respectively) linearly as cows were fed increasing proportions of AS. Methane production adjusted for dry matter intake (average=19.8 g/kg) or gross energy intake (average=5.83%) was not affected by increasing AS inclusion in the diet. When expressed on a fat-corrected milk or energy-corrected milk yield basis, CH4 production increased linearly with increasing AS dietary proportion. Urinary N excretion (g/d) increased linearly when cows were fed increasing amounts of AS in the diet, suggesting a potential for higher nitrous oxide (N2O) and NH3 emissions. Efficiency of dietary N use for milk protein secretion (g of milk N/g of N intake) declined with the inclusion of AS in the diet. Despite marked differences in chemical composition and ruminal degradability, under the conditions of this study, replacing TS with AS in dairy cow diets was not effective in reducing CH4 energy losses.

Postpartum responses of dairy cows supplemented with n-3 fatty acids for different durations during the peripartal period.

The objective of this study was to determine the effect of different durations of n-3 supplementation during the peripartal period on production and reproduction performance of Holstein dairy cows. Thirty-two Holstein dry cows (16 multiparous and 16 primiparous) were blocked within parity for similar expected calving dates 8 wk before calving. Cows within blocks were assigned randomly to 1 of 4 treatments: (1) control without n-3 fatty acid (FA) supplementation during the dry period; (2) n-3 FA supplementation during the whole dry period (8 wk); and (3) n-3 FA supplementation during the early dry period (first 5 wk; far-off), or (4) n-3 FA supplementation during the late dry period (last 3 wk; close-up). All cows received the same diet without n-3 FA after calving for the first 6 wk of lactation. Ovaries of each cow were examined 10, 17, 24, and 34 d from calving (calving=d 0) by transrectal ultrasonography to determine follicular development. Blood samples were collected at 14-d intervals starting on the first day of the dry period (8 wk before expected calving) to determine plasma concentrations of glucose, ß-hydroxybutyrate, nonesterified fatty acids, urea N, aspartate aminotransferase, and insulin. Blood samples were also collected on d 1, 10, 17, 24, 31, and 38 postpartum for determination of progesterone concentration. Milk yield was recorded daily throughout the experiment and samples were taken twice weekly (Monday and Thursday mornings) for analysis of fat, protein, and lactose. Yields of milk and 4% fat-corrected milk and milk composition were similar among treatments except for fat proportion, which tended to be lower in cows that were fed n-3 FA throughout the dry period. We observed no differences among treatments for plasma concentrations of metabolites and hormones. The cows that were fed in the 3 n-3 FA treatments had larger ovulatory follicles compared with those fed the controlled diet. Treatments did not differ significantly in terms of the number of days open, day to first service, or number of services per pregnancy. In conclusion, n-3 FA supplementation throughout the dry period or in the early or late prepartal period had no carryover reproductive postpartum benefits and no effect on the production of Holstein dairy cows.

Methane production, digestion, ruminal fermentation, nitrogen balance, and milk production of cows fed corn silage- or barley silage-based diets.

This study evaluated the effects of replacing barley silage (BS) with corn silage (CS) in dairy cow diets on enteric CH4 emissions, ruminal fermentation characteristics, digestion, milk production, and N balance. Nine ruminally cannulated lactating cows were used in a replicated 3 × 3 Latin square design (32-d period) and fed (ad libitum) a total mixed ration (TMR; forage:concentrate ratio 60:40; dry matter basis) with the forage portion consisting of either barley silage (0% CS; 0% CS and 54.4% BS in the TMR), a 50:50 mixture of both silages (27% CS; 27.2% CS and 27.2% BS in the TMR), or corn silage (54% CS; 0% BS and 54.4% CS in the TMR). Increasing the CS proportion (i.e., at the expense of BS) also involved increasing the proportion of corn grain (at the expense of barley grain). Intake and digestibility of dry matter and milk production increased linearly as the proportion of CS increased in the diet. Increasing dietary CS proportion decreased linearly the acetate molar proportion and increased linearly that of propionate. Daily CH4 emissions tended to respond quadratically to increasing proportions of CS in the diet (487, 540, and 523 g/d for 0, 27, and 54% CS, respectively). Methane production adjusted for dry matter or gross energy intake declined as the amount of CS increased in the diet; this effect was more pronounced when cows were fed the 54% CS diet than the 27% CS diet. Increasing the CS proportion in the diet improved N utilization, as reflected by decreases in ruminal ammonia concentration and urinary N excretion and higher use of dietary N for milk protein secretion. Total replacement of BS with CS in dairy cow diets offers a strategy to decrease CH4 energy losses and control N losses without negatively affecting milk performance.

Rumen fermentation and microbial population in lactating dairy cows receiving diets containing oilseeds rich in C-18 fatty acids.

Sixteen Holstein rumen-cannulated primiparous milking dairy cows were fed a control diet (CN) based on maize silage and soyabean meal during a 4-week period before the start of a 21-d experiment with oilseeds containing high concentration of linoleic acid (Linola™) or linolenic acid (NuLin™). Thereafter, four cows received ad libitum one of each of four dietary treatments comprising of CN, Linola (LN), NuLin (NL) and LN/NL (50/50 % combination). Each LN, NL and LN/NL treatment contained 6 % oil of DM. Rumen digesta samples were collected on days 6, 11, 16 and 21 and milk samples on days 13, 15 and 17. There were no effects (P>0.05) of the oilseeds on pH and concentrations of NH3-N and total volatile fatty acids, while the acetate:propionate ratio was decreased (P< 0.05). The oilseeds also decreased (P< 0.05) protozoa and increased (P< 0.1) total cellulolytic bacteria in rumen fluid, especially when containing high dietary linoleic acid (P< 0.05). The milk protein concentration was increased (P< 0.1) by the dietary linoleic acid, which produced most beneficial results. It was concluded that supplements of linoleic acid in diets of ruminants might contribute to better digestion of dietary fibre and increased quality of milk.

Effects of increasing amounts of corn dried distillers grains with solubles in dairy cow diets on methane production, ruminal fermentation, digestion, N balance, and milk production.

The objective of this study was to examine the effects of including corn dried distillers grains with solubles (DDGS) in the diet at the expense of corn and soybean meal on enteric CH4 emissions, ruminal fermentation characteristics, digestion (in sacco and apparent total-tract digestibility), N balance, and milk production of dairy cows. Twelve lactating Holstein cows were used in a triplicated 4×4 Latin square design (35-d periods) and fed (ad libitum intake) a total mixed ration containing (dry matter basis) 0, 10, 20, or 30% DDGS. Dry matter intake increased linearly, whereas apparent-total tract digestibility of dry matter and gross energy declined linearly as DDGS level in the diet increased. Increasing the proportion of DDGS in the diet decreased the acetate:propionate ratio, but this decrease was the result of reduced acetate concentration rather than increased propionate concentration. Milk yield increased linearly (up to +4kg/d) with increasing levels of DDGS in the diet and a tendency was observed for a quadratic increase in energy-corrected milk as the proportion of DDGS in the diet increased. Methane production decreased linearly with increasing levels of DDGS in the diet (495, 490, 477, and 475 g/d for 0, 10, 20, and 30% DDGS diets, respectively). When adjusted for gross energy intake, CH4 losses also decreased linearly as DDGS proportion increased in the diet by 5, 8, and 14% for 10, 20, and 30% DDGS diets, respectively. Similar decreases (up to 12% at 30% DDGS) were also observed when CH4 production was corrected for digestible energy intake. When expressed relative to energy-corrected milk, CH4 production declined linearly as the amount of DDGS increased in the diet. Total N excretion (urinary and fecal; g/d) increased as the amount of DDGS in the diet increased. Efficiency of N utilization (milk N secretion as a proportion of N intake) declined linearly with increasing inclusion of DDGS in the diet. However, productive N increased linearly with increasing proportions of DDGS in the diet, suggesting better efficiency of N use by the animal. Results from this study show that feeding DDGS to dairy cows can help to mitigate enteric CH4 emissions without negatively affecting intake and milk production.

Replacing alfalfa silage with corn silage in dairy cow diets: Effects on enteric methane production, ruminal fermentation, digestion, N balance, and milk production.

The objective of this study was to determine the effects of replacing alfalfa silage (AS) with corn silage (CS) in dairy cow total mixed rations (TMR) on enteric CH4 emissions, ruminal fermentation characteristics, apparent total-tract digestibility, N balance, and milk production. Nine ruminally cannulated lactating cows were used in a replicated 3×3 Latin square design (32-d period) and fed (ad libitum) a TMR [forage:concentrate ratio of 60:40; dry matter (DM) basis], with the forage portion consisting of either alfalfa silage (0% CS; 56.4% AS in the TMR), a 50:50 mixture of both silages (50% CS; 28.2% AS and 28.2% CS in the TMR), or corn silage (100% CS; 56.4% CS in the TMR). Increasing the CS proportion (i.e., at the expense of AS) in the diet was achieved by decreasing the corn grain proportion and increasing that of soybean meal. Intake of DM and milk yield increased quadratically, whereas DM digestibility increased linearly as the proportion of CS increased in the diet. Increasing the dietary CS proportion resulted in changes (i.e., lower ruminal pH and acetate:propionate ratio, reduced fiber digestibility, decreased protozoa numbers, and lower milk fat and higher milk protein contents) typical of those observed when cows are fed high-starch diets. A quadratic response in daily CH4 emissions was observed in response to increasing the proportion of CS in the diet (440, 483, and 434 g/d for 0% CS, 50% CS, and 100% CS, respectively). Methane production adjusted for intake of DM, and gross or digestible energy was unaffected in cows fed the 50% CS diet, but decreased in cows fed the 100% CS diet (i.e., quadratic effect). Increasing the CS proportion in the diet at the expense of AS improved N utilization, as reflected by the decreases in ruminal NH3 concentration and manure N excretion, suggesting low potential NH3 and N2O emissions. Results from this study, suggest that total replacement of AS with CS in dairy cow diets offers a means of decreasing CH4 output and N losses. However, the reduction in fiber degradation and the resulting increase in volatile solids content of the manure may lead to increased CH4 emissions from manure storage.

Supplementation of increasing amounts of linseed oil to dairy cows fed total mixed rations: effects on digestion, ruminal fermentation characteristics, protozoal populations, and milk fatty acid composition.

The effect of linseed oil (LO) supplementation on nutrient digestibility, forage (i.e., timothy hay) in sacco ruminal degradation, ruminal fermentation characteristics, protozoal populations, milk production, and milk fatty acid (FA) profile in dairy cows was investigated. Four ruminally cannulated, primiparous lactating cows were used in a 4 × 4 Latin square design (28-d periods). They were fed a total mixed ration (50:50 forage:concentrate (F:C) ratio [dry matter (DM) basis] without supplementation (control, CTL), or supplemented (wt/wt; DM basis) with LO at 2, 3, or 4%. Supplementation with LO had no effect on DM intake (19 kg/d) and apparent total-tract digestibility of nutrients (organic matter, neutral detergent fiber, acid detergent fiber, starch, and gross energy). Ruminal pH, ammonia, and total volatile FA concentrations were not changed by LO supplementation to diets. Extent of changes in volatile FA pattern and effective ruminal degradability of DM of timothy hay were minor. Neither the total numbers nor the genera distribution of protozoa was changed by the addition of increasing amounts of LO to the diet. Milk yield increased linearly (26.1, 27.3, 27.4, and 28.4 kg/d for CTL to LO4, respectively) as the amount of LO added to the diet increased. Milk fat content was not affected by LO supplementation, whereas milk protein content decreased linearly with increasing amounts of LO in the diet. Milk fat proportions of several intermediates of ruminal biohydrogenation of polyunsaturated FA (i.e., trans-10 18:1, trans-11 18:1, cis-9,trans-11 18:2, trans-11,cis-15 18:2, and cis-9,trans-11,cis-15 18:3) increased linearly with LO addition to the diet. The proportion of cis-9,cis-12 18:2 decreased linearly (2.06, 1.99, 1.91, and 1.83% for CTL to LO4, respectively) as the amount of LO in the diet increased. Milk fat content of cis-9,cis-12,cis-15 18:3 increased as the level of LO in the diet increased up to 3% but no further increase was observed when 4% of LO was fed (0.33, 0.79, 0.86, and 0.86% for CTL to LO4, respectively). A similar quadratic response to LO supplementation was also observed for cis-5,cis-8,cis-11,cis-14,cis-17 20:5 and cis-5,cis-7,cis-10,cis-13,cis-16 22:5. The results of the present study show that LO can be safely supplemented up to 4% in forage-based diets of dairy cows to enrich milk with potential health beneficial FA (i.e., n-3 FA) without causing any detrimental effects on rumen function, digestion, and milk production.

Abomasal or ruminal administration of flax oil and hulls on milk production, digestibility, and milk fatty acid profile of dairy cows.

Four ruminally fistulated primiparous lactating Holstein cows were assigned to a 4 × 4 Latin square design to determine the effects of the site of administration (rumen or abomasum) of flax oil and flax hulls on diet digestibility and milk fatty acid profile of dairy cows. The treatments were 1) oil and hulls administered in the rumen and abomasal infusion of water (RUM/RUM), 2) oil and hulls infused in the abomasum (ABO/ABO), 3) oil administered in the rumen and hulls infused in the abomasum (RUM/ABO), and 4) oil infused in the abomasum and hulls placed in the rumen (ABO/RUM). Cows on the ABO/ABO and RUM/RUM treatments had the highest and lowest amounts of basal dry matter eaten, respectively. Higher dry matter digestibility was obtained when flax oil bypassed the rumen (ABO/ABO and ABO/RUM) compared with when flax oil was administered directly in the rumen (RUM/ABO and RUM/RUM). Apparent digestibility of ether extract was higher when flax hulls were administered in the rumen (RUM/RUM and ABO/RUM) compared with when flax hulls were infused in the abomasum (ABO/ABO and RUM/ABO). The lowest digestibility of acid detergent fiber and neutral detergent fiber was obtained when both flax products were added in the rumen, which may be attributed to the high amount of oil present in the rumen (7.8% of total dry matter input). The lowest yield of 4% fat-corrected milk was obtained for cows on the RUM/RUM treatment, probably as a result of lower dry matter intake and digestibility of fiber. Milk concentrations of protein, fat, total solids, and lactose were similar among treatments. Administration of oil and hulls in the rumen resulted in the highest concentrations of intermediate products of biohydrogenation and total trans fatty acids in milk fat compared with the other treatments. All ratios of n-6 to n-3 fatty acids in milk fat were lower than the 4 to 1 ratio recommended to improve human health. These results suggest that the presence of both flax oil and flax hulls in the rumen decreases 4% fat-corrected milk yield and digestibility but provides a desirable fatty acid profile of milk to enhance consumers' health.

Milk composition, milk fatty acid profile, digestion, and ruminal fermentation in dairy cows fed whole flaxseed and calcium salts of flaxseed oil.

Four ruminally lactating Holstein cows averaging 602+/-25 kg of body weight and 64+/-6 d in milk at the beginning of the experiment were randomly assigned to a 4 x 4 Latin square design to determine the effects of feeding whole flaxseed and calcium salts of flaxseed oil on dry matter intake, digestibility, ruminal fermentation, milk production and composition, and milk fatty acid profile. The treatments were a control with no flaxseed products (CON) or a diet (on a dry matter basis) of 4.2% whole flaxseed (FLA), 1.9% calcium salts of flaxseed oil (SAL), or 2.3% whole flaxseed and 0.8% calcium salts of flaxseed oil (MIX). The 4 isonitrogenous and isoenergetic diets were fed for ad libitum intake. Experimental periods consisted of 21 d of diet adaptation and 7 d of data collection and sampling. Dry matter intake, digestibility, milk production, and milk concentrations of protein, lactose, urea N, and total solids did not differ among treatments. Ruminal pH was reduced for cows fed the CON diet compared with those fed the SAL diet. Propionate proportion was higher in ruminal fluid of cows fed CON than in that of those fed SAL, and cows fed the SAL and CON diets had ruminal propionate concentrations similar to those of cows fed the FLA and MIX diets. Butyrate concentration was numerically higher for cows fed the SAL diet compared with those fed the FLA diet. Milk fat concentration was lower for cows fed SAL than for those fed CON, and there was no difference between cows fed CON and those fed FLA and MIX. Milk yields of protein, fat, lactose, and total solids were similar among treatments. Concentrations of cis-9 18:1 and of intermediates of ruminal biohydrogenation of fatty acids such as trans-9 18:1 were higher in milk fat of cows fed SAL and MIX than for those fed the CON diet. Concentration of rumenic acid (cis-9, trans-11 18:2) in milk fat was increased by 63% when feeding SAL compared with FLA. Concentration of alpha-linolenic acid was higher in milk fat of cows fed SAL and MIX than in milk of cows fed CON (75 and 61%, respectively), whereas there was no difference between FLA and CON. Flaxseed products (FLA, SAL, and MIX diets) decreased the n-6 to n-3 fatty acid ratio in milk fat. Results confirm that flax products supplying 0.7 to 1.4% supplemental fat in the diet can slightly improve the nutritive value of milk fat for better human health.

Evaluation of cardiac abnormalities by Doppler echocardiography in a large nationwide multicentric cohort of patients with systemic sclerosis.

OBJECTIVES: There is increasing concern about heart and pulmonary vascular involvement in systemic sclerosis (SSc). One of the most severe complications of SSc is pulmonary arterial hypertension (PAH). There has been an increased awareness of left ventricular (LV) diastolic abnormalities in SSc patients. However, previous studies have generally been conducted in small populations. The aims of this study were to prospectively screen for PAH and to describe echocardiographic parameters in a large group of SSc patients. METHODS: This prospective study was conducted in 21 centres for SSc in France. Patients without severe pulmonary function abnormalities, severe cardiac disease and known PAH underwent Doppler echocardiography performed by a reference cardiologist. RESULTS: Of the 570 patients evaluated, PAH was suspected in 33 patients and was confirmed in 18 by right heart catheterisation. LV systolic dysfunction was rare (1.4%). LV hypertrophy was found in 22.6%, with LV diastolic dysfunction in 17.7%. These LV abnormalities were influenced by age, gender and blood pressure. We identified a small group of 21 patients with a restrictive mitral flow pattern in the absence of any other cardiopulmonary diseases, suggesting a specific cardiac involvement in SSc. CONCLUSIONS: Left and right heart diseases, including PAH, LV hypertrophy and diastolic dysfunction, are common in SSc. However, a small subset of patients without any cardiac or pulmonary diseases have a restrictive mitral flow pattern that could be due to primary cardiac involvement of SSc. The prognostic implications of the LV abnormalities will be evaluated in the 3-year follow-up of this cohort.

In vitro metabolism of flax lignans by ruminal and faecal microbiota of dairy cows.

AIMS: To determine the in vitro conversion of plant lignans from two flax products (hull and seed) into the mammalian lignans, enterolactone and enterodiol, by bovine ruminal and faecal microbiota. METHODS AND RESULTS: Flax seeds and hulls were incubated in vitro over a 96-h time course with ruminal or faecal inoculum. Plant lignans in flax seeds and hulls averaged 9.2 and 32.0 nmol mg(-1), respectively. The highest net production of enterodiol at 72 and 96 h of incubation was obtained with flax hulls incubated with faecal microbiota. There was no difference in net production of enterodiol between flax products within the first 24 h of incubation. In general, net production of enterolactone over the 96-h time course was significantly higher for flax products incubated with ruminal than with faecal microbiota. Net production of enterolactone at 72 and 96 h of incubation was greater for flax hulls than flax seeds. CONCLUSIONS: Results of the present experiment suggest that, of the metabolites studied, the main mammalian lignan metabolite produced from flax hulls and seeds by ruminal microbiota is enterolactone while faecal microbiota leads mainly to the net production of enterodiol. SIGNIFICANCE AND IMPACT OF THE STUDY: This research will improve the understanding of the metabolic pathway of mammalian lignans in dairy cows, in order to enable targeted manipulation of their quantities in milk.

Quality of embryos produced from dairy cows fed whole flaxseed and the success of embryo transfer.

The objective of the experiment was to determine the effects of fat supplementation on embryo quality of dairy cows and the subsequent success of embryo transfer into recipient heifers fed the same sources of fat. A total of 30 lactating Holstein cows were allotted on d 18 postpartum to 2 groups of 15 donor cows blocked for similar calving dates. Total mixed diets based on silage and fat supplements were fed for ad libitum intake. On a dry matter basis, diets fed to donor cows contained 7.9% whole flaxseed or 2.8% calcium salts of palm oil and those fed to recipient heifers contained 11.4% whole flaxseed or 4.2% calcium salts of palm oil. The experiment with donor cows was carried out between d 18 and 109 of lactation. The experimental diets were fed to 121 recipient heifers from wk 8 before estrus synchronization and superovulation to d 50 of gestation. Dietary fat fed to donor cows had no effect on the number of viable embryos per cow (3.7 +/- 0.5), the number of degenerated embryos per cow (1.8 +/- 0.4), or the number of unfertilized oocytes per cow (2.1 +/- 0.8). But feeding flaxseed decreased fertilization rate (64.3 vs. 78.4%) and the percentage of grade 1 to 2 embryos (56.5 vs. 74.1%) and increased the embryo degeneration percentage (27.4 vs. 18.2%) compared with feeding calcium salts of palm oil. There was no effect of diets fed to donor cows and those fed to recipient heifers for pregnancy rate of heifers. Supplementation with a rich source of n-3 fatty acids decreased quality of embryos from donor lactating dairy cows compared with feeding calcium salts of palm oil, but had no effect on the subsequent pregnancy rate of heifers receiving frozen grade-1 embryos.

Alfalfa cut at sundown and harvested as baleage improves milk yield of late-lactation dairy cows.

Alfalfa (Medicago sativa L.) cut at sundown has been shown to contain greater concentration of total nonstructural carbohydrates (TNC) than that cut at sunup. Fourteen multiparous (8 ruminally cannulated) and 2 primiparous lactating dairy cows were randomly assigned to 2 treatments in a crossover design (2 periods of 24 d) to investigate the effects of alfalfa daytime cutting management on ruminal metabolism, nutrient digestibility, N balance, and milk yield. Half of each alfalfa field (total of 3 fields) was cut at sundown (PM) after a sunny day, whereas the second half was cut at sunup (AM) on the following day. Both PM and AM cuts were field-wilted and harvested as baleage (531 +/- 15.0 g of dry matter/kg of fresh matter). Bales (PM and AM) were ranked according to their concentrations of TNC, paired, and each pair of PM and AM baleages was then assigned to each experimental day (total of 48 d). The difference in TNC concentration between PM and AM baleages fed during the 10 d of data and sample collection varied from -10 to 50 g/kg of dry matter. Each pair of baleage was fed ad libitum to cows once daily with no concentrate. Ruminal molar proportion of acetate and total volatile fatty acid concentration were greater in animals fed the AM baleage, whereas the proportion of valerate was greater with PM baleage; no other significant changes in ruminal molar proportions of volatile fatty acids were observed between forage treatments. Digestible organic matter intake, organic matter digestibility, and plasma Lys concentration were significantly greater in cows fed PM alfalfa, suggesting that more nutrients were available for milk synthesis. Significantly lower body weight gain and retained N as a proportion of N intake were observed in cows fed PM alfalfa, thus suggesting that nutrients were channeled to milk synthesis rather than to body reserves. Intake of dry matter (+1.0 kg/d), and yields of milk (+1.0 kg/d), milk fat (+70 g/d), and milk protein (+40 g/d) were significantly greater in cows fed PM vs. AM alfalfa. Concentration of milk urea N and excretion of urea N as a proportion of total urinary N were significantly reduced, and milk N efficiency was increased when feeding PM vs. AM alfalfa, indicating an improvement in N utilization. Increasing the TNC concentration of alfalfa by shifting forage cutting from sunup to sundown improved N utilization and milk production in late-lactation dairy cows.

Hepatic lipid metabolism in transition dairy cows fed flaxseed.

Thirty-three Holstein cows averaging 687 kg of body weight were allotted 6 wk before the expected date of parturition to 11 groups of 3 cows blocked within parity for similar calving dates to determine the effects of feeding different sources of fatty acids on blood parameters related to fatty liver and profile of fatty acids in plasma and liver. Cows were fed lipid supplements from 6 wk before the expected date of parturition until d 28 of lactation. Cows within each block were assigned to 1 of 3 isonitrogenous and isoenergetic dietary supplements: control with no added lipids (CO); unsaturated lipids supplied as whole flaxseed (FL; 3.3 and 11.0% of the dry matter in prepartum and postpartum diets, respectively); and saturated lipids supplied as Energy Booster (EB; 1.7 and 3.5% of the DM in prepartum and postpartum diets, respectively). Diets EB and FL had similar ether extract concentrations. Multiparous cows fed EB had lower dry matter intake and milk production, higher concentrations of nonesterified fatty acids and beta-hydroxybutyrate in plasma and triglycerides (TG) and total lipids in liver, and lower concentrations of plasma glucose and liver glycogen than those fed FL and CO. Production of 4% fat-corrected milk was similar among treatments. Multiparous cows fed FL had the highest liver concentrations of glycogen on wk 2 and 4 after calving and lowest concentrations of TG on wk 4 after calving. Liver C16:0 relative percentages in multiparous cows increased after calving whereas those of C18:0 decreased. Relative percentages of liver C16:0 were higher in wk 2 and 4 postpartum for multiparous cows fed EB compared with those fed CO and FL; those of C18:0 were lower in wk 4 postpartum for cows fed EB compared with those fed CO and FL. Liver C18:1 relative percentages of multiparous cows increased after calving and were higher in wk 4 for cows fed EB compared with those fed CO and FL. The inverse was observed for liver C18:2 relative percentages. In general, diets had more significant effects on plasma concentrations of nonesterified fatty acids, beta-hydroxybutyrate, and glucose and liver profiles of fatty acids, TG, total lipids, and glycogen of multiparous than primiparous cows. These data suggest that feeding a source of saturated fatty acids increased the risk of fatty liver in the transition cow compared with feeding no lipids or whole flaxseed. Feeding flaxseed compared with no lipids or a source of saturated fatty acids from 6 wk before calving could be a useful strategy to increase liver concentrations of glycogen and decrease liver concentrations of TG after calving, which may prevent the development of fatty liver in the transition dairy cow.

Effects of essential oils on digestion, ruminal fermentation, rumen microbial populations, milk production, and milk composition in dairy cows fed alfalfa silage or corn silage.

Four Holstein cows fitted with ruminal cannulas were used in a 4 x 4 Latin square design (28-d periods) with a 2 x 2 factorial arrangement of treatments to investigate the effects of addition of a specific mixture of essential oil compounds (MEO; 0 vs. 750 mg/d) and silage source [alfalfa silage (AS) vs. corn silage (CS)] on digestion, ruminal fermentation, rumen microbial populations, milk production, and milk composition. Total mixed rations containing either AS or CS as the sole forage source were balanced to be isocaloric and isonitrogenous. In general, no interactions between MEO addition and silage source were observed. Except for ruminal pH and milk lactose content, which were increased by MEO supplementation, no changes attributable to the administration of MEO were observed for feed intake, nutrient digestibility, end-products of ruminal fermentation, microbial counts, and milk performance. Dry matter intake and milk production were not affected by replacing AS with CS in the diet. However, cows fed CS-based diets produced milk with lower fat and higher protein and urea N concentrations than cows fed AS-based diets. Replacing AS with CS increased the concentration of NH(3)-N and reduced the acetate-to-propionate ratio in ruminal fluid. Total viable bacteria, cellulolytic bacteria, and protozoa were not influenced by MEO supplementation, but the total viable bacteria count was higher with CS- than with AS-based diets. The apparent digestibility of crude protein did not differ between the AS and CS treatments, but digestibilities of neutral detergent fiber and acid detergent fiber were lower when cows were fed CS-based diets than when they were fed AS-based diets. Duodenal bacterial N flow, estimated using urinary purine derivatives and the amount of N retained, increased in cows fed CS-based diets compared with those fed AS-based diets. Feeding cows AS increased the milk fat contents of cis-9, trans-11 18:2 (conjugated linoleic acid) and 18:3 (n-3 fatty acid) compared with feeding cows CS. Results from this study showed limited effects of MEO supplementation on nutrient utilization, ruminal fermentation, and milk performance when cows were fed diets containing either AS or CS as the sole forage source.

Effects of lasalocid or monensin supplementation on digestion, ruminal fermentation, blood metabolites, and milk production of lactating dairy cows.

Six ruminally fistulated midlactating multiparous Holstein cows were used in a double 3 x 3 Latin square design (35-d periods) to study the effects of lasalocid (LAS) and monensin (MON) supplemented at 24 mg/ kg of dry matter on digestion, ruminal fermentation, blood metabolites, and milk production. Cows were blocked according to milk production and fed a red clover silage-based total mixed ration (17.8% crude protein) without supplementation or supplemented with LAS or MON. Daily dry matter intake, milk production, and milk fat and protein concentrations were similar among treatments and averaged 23.5 kg, 36.6 kg, 3.36%, and 3.38%, respectively. Rumen lipogenic:glucogenic volatile fatty acids and NH(3)-N concentration were lower, and apparent digestibility of dry matter, organic matter, crude protein, and gross energy were higher with than without ionophore supplementation. Compared with LAS, MON increased concentrations of plasma urea-N and milk urea-N, and excretion of urinary urea-N and total N. Monensin also decreased N retention and tended to reduce plasma concentration of nonessential AA in comparison with LAS. Both ionophores reduced daily fecal excretion of N by 13 g compared with the control, but MON increased daily losses of urinary N by 36 g compared with LAS. Results from this study suggest that postabsorptive metabolism of N might be altered by the type of ionophore fed.