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This study investigated the use of K2CO3 as dietary buffer to prevent or to recover from low milk fat production when early-lactating dairy goats are fed a high-starch, low-fiber (HSLF) diet. At kidding, 30 Alpine goats housed in pens with Calan gate feeders received a total mixed ration with a forage-to-concentrate ratio of 55:45 on a dry matter (DM) basis for a baseline period of 27 ± 4 d. Goats (milk yield, 4.14 ± 0.88 kg/d; milk fat, 4.28 ± 0.52%; mean ± SD) were then assigned to 1 of 10 blocks according to parity (first vs. second or more) and milk fat concentration, and fed a HSLF diet containing 45% forages and 55% concentrates for 2 experimental periods of 28 d. Treatments were identified as (1) control, in which the HSLF diet was fed throughout both periods; (2) preventive, in which the HSLF diet supplemented with K2CO3 (1.6% of DM) was fed during both periods; and (3) recovery, in which the HSLF diet was fed during the first period (P1) and the HSLF diet supplemented with K2CO3 was fed during the second period (P2). Data from P1 and P2 were analyzed separately. In P1, preplanned contrasts were used to evaluate the preventive effect of K2CO3 (control and recovery, both groups receiving the same diet during this period, vs. preventive), and in P2, to assess the potential of K2CO3 to alleviate an already existing state of low milk fat (control vs. recovery and preventive vs. recovery). Feeding the HSLF diet in P1 moderately decreased milk fat concentration (−16%) and yield (−13%) as compared with baseline. Dietary addition of K2CO3 decreased DM intake by 12 and 14% in P1 and P2, respectively. Ruminal pH was not different among treatments. There was also no significant difference in milk yield (4.13 and 3.71 kg/d on average in P1 and P2, respectively) for any tested contrasts. In P1, milk fat concentration and yield did not differ among goats fed control (3.58% and 151 g/d, respectively) and preventive (3.67% and 148 g/d, respectively) diets. In P2, milk fat concentration and yield did not differ among goats fed the control diet (3.38% and 137 g/d, respectively), and diets where K2CO3 was used as preventive (3.44% and 126 g/d, respectively) or recovery treatment (3.25% and 113 g/d, respectively). Supplementing a high-concentrate diet with 1.6% K2CO3 was therefore not effective in either preventing or suppressing already existing conditions of low milk fat production in dairy goats.

Our primary objective was to determine the effects of the abomasal infusion of 16-carbon (16C) and 22-carbon (22C) fatty acids (FA) on apparent FA digestibility, plasma FA concentrations, and their incorporation into milk fat in cows. Our secondary objective was to study the effects of 1-carbon donors choline and l-serine on these variables. Five rumen-cannulated Holstein cows (214 ± 4.9 d in milk; 3.2 ± 1.1 parity) were enrolled in a 5 × 5 Latin square experiment with experimental periods lasting 6 d. Abomasal infusates consisted of (1) palmitic acid (PA; 98% 16:0 of total fat), (2) PA + choline chloride (PA+CC; 50 g/d of choline chloride), (3) PA + l-serine (PA+S; 170 g/d of l-serine), (4) behenic acid (BA; 92% 22:0 of total fat), and (5) docosahexaenoic acid algal oil (DHA; 47.5% DHA of total fat). Emulsions were formulated to provide 301 g/d of total FA and were balanced to provide a minimum of 40 and 19 g/d of 16:0 and glycerol, respectively, to match the content found in the infused algal oil. Apparent digestibility of FA was highest in DHA, intermediate in PA, and lowest in BA. Digestibility of 16C FA was lowest in BA and highest in PA. The digestibility of 22C FA was highest in DHA relative to BA (99 vs. 58%), whereas 1-carbon donors had no effect on 22C FA digestibility. Plasma 16C FA concentrations were greatest with PA treatment, and 22C FA concentrations were ~3-fold greater in DHA-treated cows relative to all other treatments. Milk fat 16:0 content was highest in PA relative to BA and DHA (e.g., 37 vs. 27% in PA and DHA), whereas the milk yield of 16:0 was higher in PA relative to DHA (i.e., 454 vs. 235 g/d). Similarly, milk 22:0 content and yield were ~10-fold higher in BA relative to all other treatments, whereas DHA treatment resulted in higher content and yield of 22:6 in milk fat relative to all other treatments (41- and 38-fold higher, respectively). Consequently, the content of FA >16C (i.e., preformed) was higher in milk fat from cows infused with BA and DHA relative to PA. De novo FA content in milk did not differ between PA, PA+CC, and PA+S (~16% of milk fat) but was higher in BA and DHA treatments (19 and 21%, respectively). We conclude that FA carbon chain length and degree of saturation affected FA digestibility and availability for absorption as well as their incorporation into milk fat. The abomasal infusion of choline chloride and l-serine did not modify these variables relative to infusing palmitic acid alone.

In high-yielding dairy cows, some fertility traits can be influenced by the fatty acid (FA) composition of the follicular fluid during early lactation. The first objective of the current study was to evaluate the potential of dietary supplements enriched in specific FA to influence the FA composition of follicular fluid lipid classes in early lactation dairy cows. The second objective was to determine the influence of the resulting follicular fluid FA composition on the folliculogenesis, lipid and energy metabolism of granulosa cells, as well as oocyte quality and embryo development. Twenty Holstein multiparous cows in late gestation were randomly assigned to 200 g/d of FA supplements enriched in (1) palmitic acid (control treatment; 82% 16:0; PA) in the rumen or (2) palmitoleic acid (sea buckthorn oil; 27% cis-9 16:1, 28% 16:0, 22% cis-9 18:1, and 11% cis-9,cis-12 18:2; SBT) in the abomasum. The treatment period ranged from 20 ± 5 d precalving to 67 ± 2 d postcalving. Cumulus-oocyte complexes, granulosa cells, and follicular fluid were recovered from 2 sequential sessions of ovum pick-up (OPU-1 and OPU-2) at 46 and 67 ± 2 d postcalving (mean ± standard deviation). On the same days, blood samples were collected. Milk performance was recorded, and feed and milk samples were collected from d 8 to 10 ± 3 (onset of lactation), d 35 to 37 ± 2 (before OPU-1), and d 63 to 65 ± 2 (before OPU-2). Treatments did not affect milk yield or fat concentration throughout the experimental trial. Compared with PA, SBT increased the cis-9 16:1 concentration in milk fat, in plasma esterified lipid classes (phospholipids, cholesterol esters, and triacylglycerols), and in follicular fluid phospholipids and cholesterol esters at OPU-1. Abundance of mRNA for stearoyl-CoA desaturase 1 and 5, and perilipin 2 in granulosa cells was not different between treatments, but an increase in the level of stearoyl-CoA desaturase 5 was observed between the 2 OPU periods. Treatments did not affect oocyte quality and developmental capacity or embryo lipid metabolism when cultivated in vitro. These results suggest that limited modifications in the FA composition of the oocyte microenvironment via dietary lipid supplements enriched in specific FA had no major effects on granulosa cell metabolism and oocyte developmental capacity in early lactation cows.

The objective of the current study was first to characterize lipid raft microdomains isolated as detergent-resistant membranes (DRM) from mammary gland tissue, and second to determine how dietary fatty acids (FA) such as conjugated linoleic acid (CLA), 19:1 cyclo, and long-chain n-3 polyunsaturated FA affect lipid raft markers of mammary cells, and to finally establish relationships between these markers and lactation performance in dairy cows. Eight Holstein cows were used in a replicated 4 × 4 Latin square design with periods of 28 d. For the first 14 d, cows received daily an abomasal infusion of (1) 406 g of a saturated FA supplement (112 g of 16:0 + 230 g of 18:0) used as a control; (2) 36 g of a CLA supplement (13.9 g of trans-10,cis-12 18:2) + 370 g of saturated FA; (3) 7 g of Sterculia fetida oil (3.1 g of 19:1 cyclo, STO) + 399 g of saturated FA; or (4) 406 g of fish oil (55.2 g of cis-5,cis-8,cis-11,cis-14,cis-17 20:5 + 59.3 g of cis-4,cis-7,cis-10,cis-13,cis-16,cis-19 22:6, FO). Mammary biopsies were harvested on d 14 of each infusion period and were followed by a 14-d washout interval. Cholera toxin subunit B, which specifically binds to ganglioside M-1 (GM-1), a lipid raft marker, was used to assess its distribution in DRM. Infusions of CLA, STO, and FO were individually compared with the control, and significance was declared at P ≤ 0.05. Milk fat yield was decreased with CLA and FO, but was not affected by STO. Milk lactose yield was decreased with CLA and STO, but was not affected by FO. Mammary tissue shows a strong GM-1-signal enrichment in isolated DRM from mammary gland tissue. Caveolin (CAV) and flotillin (FLOT) are 2 proteins considered as lipid raft markers and they are present in DRM from mammary gland tissue. Distributions of GM-1, CAV-1, and FLOT-1 showed an effect of treatments determined by their subcellular distributions in sucrose gradient fractions. Regardless of treatments, data showed positive relationships between the yield of milk fat, protein, and lactose, and the abundance GM-1 in DRM fraction. Milk protein yield was positively correlated with relative proportion of FLOT-1 in the soluble fraction, whereas lactose yield was positively correlated with relative proportion of CAV-1 in the DRM fractions. Infusion of CLA decreased mRNA abundance of CAV-1, FLOT-1, and FLOT-2. Regardless of treatments, a positive relationship was observed between fat yield and mRNA abundance of FLOT-2. In conclusion, although limited to a few markers, results of the current experiment raised potential links between variation in specific biologically active component of raft microdomains in bovine mammary gland and lactation performances in dairy cows.

Deoiled soy lecithin is a feed additive enriched in phospholipids. Our study evaluated the effects of dietary deoiled soy lecithin supplementation on (1) milk production and composition, (2) plasma and milk fatty acid (FA) content and yield, and (3) apparent FA digestibility and absorption in lactating dairy cows fed fractionated palm fat. In a split-plot Latin square design, 16 Holstein cows (160 ± 7 days in milk; 3.6 ± 1.2 parity) were randomly allocated to a main plot receiving a corn silage and alfalfa haylage-based diet with palm fat containing either moderate (MPA) or high palmitic acid (HPA) content at 1.75% of ration dry matter (72 or 99% palmitic acid, respectively; n = 8/palm fat diet). On each palm fat diet, deoiled soy lecithin was top-dressed at 0, 0.12, 0.24, or 0.36% of ration dry matter in a replicated 4 × 4 Latin square design. Following a 14-d covariate period, lecithin supplementation spanned 14 d, with milk and blood collected during the final 3 d. Milk composition and pooled plasma markers were measured. The statistical model included the fixed effects of palm fat type, lecithin dose, period, and the interaction between palm fat type and lecithin dose. The random effect of cow nested within palm fat group was also included. Lecithin linearly decreased dry matter intake. In cows fed HPA, lecithin feeding reduced milk fat content and tended to decrease milk fat yield. Although no changes in milk yield were observed, a quadratic reduction in 3.5% fat-corrected milk was observed with increasing lecithin dose. Lecithin linearly increased energy-corrected milk efficiency in cows fed MPA. Lecithin supplementation also decreased milk urea nitrogen, relative to unsupplemented cows. The proportion of 16-carbon FA in milk fat decreased linearly with lecithin dose, whereas 18-carbon FA increased linearly. Lecithin reduced de novo FA (16-carbon) content and tended to increase preformed FA (16-carbon) content in a linear manner. Compared with MPA, HPA diets reduced apparent total and 16-carbon FA digestibility and absorption. Deoiled soy lecithin feeding did not modify FA digestibility or absorption. Our observations suggest that soy lecithin feeding modifies rumen digestion to reduce dry matter intake and change milk composition.

Tall fescue might be an alternative to timothy in northeastern North America because of its tolerance of recurring drought periods and its good summer regrowth, but is not always considered as an option in dairy rations because of its possible lack of palatability. The objective of this study was to evaluate the effects on the performance of lactating dairy cows of (1) replacing timothy silage by tall fescue silage, offered as sole forage in the diet or in combination with alfalfa silage, and (2) feeding tall fescue as silage (35% dry matter, DM) or haylage (55% DM). Experimental diets with a forage-to-concentrate ratio of 70:30 were (1) 100% timothy silage (TS); (2) 100% tall fescue silage (TFS); (3) 55:45 timothy:alfalfa silages (TS + AS); (4) 55:45 tall fescue:alfalfa silages (TFS + AS); and (5) 100% tall fescue haylage (TFH). Fifteen Holstein cows in mid-lactation (5 fitted with a rumen fistula) were randomly assigned to treatments in a triple 5 × 5 Latin square design with treatment periods of 21 d. Preplanned contrasts were timothy versus tall fescue silages, sole grass species versus grass-alfalfa, interaction between sole grass species and grass-alfalfa, and TFS versus TFH. Grass species did not affect dry matter intake (DMI) or milk yield and fat concentration. Milk protein concentration was not affected by grass species when offered in combination with alfalfa, but it was higher with the TS diet than the TFS diet when offered as sole forages. Adding alfalfa to either tall fescue or timothy silage resulted in greater DMI and milk yield, but lower milk fat concentration, than when the grass silages were the sole forage in the diet. The molar proportion of propionate in the rumen was greater when cows were fed diets with tall fescue silage compared with timothy silage, which resulted in a lower acetate-to-propionate ratio. Milk fat concentrations of fatty acids from microbial origin, namely branched-chain fatty acids, were greater when grass silage, and especially timothy silage, were fed as sole forages rather than with alfalfa silage. Feeding TFH rather than TFS caused a decrease in DMI and tended to lower milk protein concentration, but did not affect milk yield. A more fibrolytic fermentation profile was observed in rumen of cows fed TFH compared with TFS, as indicated by the increase in the molar proportion of acetate and the higher acetate-to-propionate ratio in rumen fluid, and a concomitant increase in branched-chain fatty acid concentration in milk fat. Tall fescue as silage or haylage is a valuable alternative to timothy silage for lactating dairy cows.