Effects of postpartum dietary fat and body condition score at parturition on plasma, adipose tissue, and milk fatty acid composition of lactating beef cows

Two experiments were conducted with lactating Angus x Gelbvieh beef cows to determine the effects of postpartum lipid supplementation, BCS at parturition, and day of lactation on fatty acid profiles in plasma, adipose tissue, and milk. In Exp. 1, 36 pri-miparous cows (488 +/- 10 kg of initial BW; 5.5 +/- 0.02 initial BCS) were given ad libitum access to hay and assigned randomly to a low-fat (control) supplement or supplements with cracked, high-linoleate safflower seeds (linoleate) or cracked, high-oleate safflower seeds (oleate) from d 3 to 90 of lactation. Diets were formulated to be isonitrogenous and isocaloric; safflower seed diets provided 5% of DMI as fat. Plasma and milk samples were collected on d 30, 60, and 90 of lactation. Adipose tissue biopsies were collected near the tail-head region of cows on d 45 and 90 of lactation. In Exp. 2, 3-yr-old cows achieving a BCS of 4 +/- 0.07 (479 +/- 36 kg of BW) or 6 +/- 0.07 (580 +/- 53 kg of BW) at parturition were used in a 2-yr experiment (n = 36/yr). Beginning 3 d postpartum through d 61 of lactation, cows were fed diets similar to those of Exp. 1. Adipose tissue and milk samples were collected on d 30 and 60, and plasma was collected on d 31 and 61 of lactation. Responses to postpartum dietary treatment were comparable in both experiments. Cows fed linoleate and oleate had greater (P < 0.001) total fatty acid concentrations in plasma than cows fed control. Except for 15:1, milk fatty acids with <18 carbons were greatest (P < or = 0.01) for cows fed control, whereas milk from cows fed linoleate had the greatest (P < or = 0.02) 18:1trans-11, 18:2n-6, and cis-9, trans-11 CLA. Milk from cows fed oleate had the greatest (P < 0.001) 18:1cis-9. In Exp. 1, total fatty acid concentrations in adipose tissue samples decreased at d 90 compared with d 45 of lactation, but the fatty acid profile of cow adipose tissue was not affected (P = 0.14 to 0.80) by dietary treatment. In Exp. 2, the percentage of cis-9, trans-11 CLA in adipose tissue of cows with a BCS of 6 decreased (P = 0.001) from d 30 to 60 of lactation. Plasma and milk fatty acid composition reflected alterations in postpartum diet. Less medium-chain fatty acids and more 18-carbon fatty acids in milk were indicative of reduced de novo fatty acid synthesis in the mammary gland of beef cows fed lipid supplements; however, the metabolic demands of lactation prevented the deposition of exogenously derived fatty acids in adipose tissue through d 90 of lactation.     

Fatty acid composition of plasma, medial basal hypothalamus, and uterine tissue in primiparous beef cows fed high-linoleate safflower seeds

The experimental objectives were to evaluate the influence of supplemental high-linoleate safflower seeds on fatty acid concentrations in plasma, medial basal hypothalamus, uterine tissues, and serum 13,14-dihydro-15-keto PGF(2)alpha metabolite (PGFM) in primiparous beef cows during early lactation. Beginning 1 d postpartum, 18 primiparous, crossbred beef cows (411 +/- 24.3 kg of BW) were fed foxtail millet hay at 1.68% of BW (DM basis) and either a low-fat supplement (control: 63.7% cracked corn; 33.4% safflower seed meal; and 2.9% liquid molasses; DM basis) at 0.35% of BW (n = 9) or a supplement (linoleate) containing 95.3% cracked high-linoleate (79% 18:2n-6) safflower seeds and 4.7% liquid molasses (DM basis) at 0.23% of BW (n = 9). Diets were formulated to be isonitrogenous and isocaloric. The linoleate diet contained 5.4% of DMI as fat vs. 1.2% for control. Beginning 1 d postpartum, cattle were bled every 3 d for collection of serum and plasma. Cattle were slaughtered at 37 +/- 3 d postpartum for collection of the medial basal hypothalamus, myometrium, endometrium, caruncular tissue, intercaruncular tissue, and oviduct. Feeding linoleate increased (P = 0.001) plasma concentrations of 18:2n-6, 18:2cis-9 trans-11 and total unsaturated fatty acids; however, 18:1trans-11 did not differ (P = 0.19) between treatments. Concentrations of 20:5n-3 in the medial basal hypothalamus tended (P = 0.10) to be greater for cattle fed linoleate. Concentrations of fatty acids in the oviduct were greater (P < 0.05) than in other uterine tissues. Cows fed linoleate had greater (P = 0.05) concentrations of 18:3n-3 in the endometrium and less (P = 0.06) 18:2cis-9 trans-11 in the myometrium than cows fed the control. Supplemental fat increased (dietary treatment x day postpartum, P = 0.01) concentrations of PGFM in serum more in linoleate than control cows from d 3 to 9 postpartum. Lipid supplementation early in the postpartum period altered the fatty acid composition of medial basal hypothalamus, uterine tissue, and serum concentrations of PGFM. The most novel observation was that the oviduct appeared to be the most sensitive tissue to additional dietary linoleic acid, which could potentially influence fertility.     

Effects of body condition score at parturition and postpartum supplemental fat on adipose tissue lipogenic activity of lactating beef cows

Three-year-old Angus x Gelbvieh beef cows nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of initial BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of initial BW) at parturition were used in a 2-yr experiment (n = 36/yr) to determine the effects of BCS at parturition and postpartum lipid supplementation on cow adipose tissue lipogenesis. Beginning 3 d postpartum, cows within each BCS were randomly assigned to be fed hay and a low-fat control supplement or supplements with either cracked high-linoleate safflower seeds or cracked high-oleate safflower seeds until d 60 of lactation. Diets were formulated to be isonitrogenous and isocaloric, and safflower seed diets provided 5% DMI as fat. Adipose tissue biopsies were collected near the tail-head region of cows on d 30 and 60 of lactation. Dietary treatment did not affect (P > or = 0.43) adipose tissue lipogenesis. Body condition score at parturition did not affect acetate incorporation into lipid (P = 0.53) or activity of acetyl CoA carboxylase (P = 0.77) or fatty acid synthase (P = 0.18). Lipoprotein lipase activity and palmitate incorporation into triacyl-glycerol tended to be greater (P = 0.06), and palmitate esterification into total acylglycerols was greater (P = 0.01) in cows with a BCS of 4 at parturition. Mean activity of acetyl-CoA carboxylase (P < 0.001), lipoprotein lipase (P = 0.01), and rate of palmitate incorporation into monoacylglycerol (P = 0.02), diacylglycerol (P = 0.001), triacylglycerol (P = 0.003), and total acylglycerols (P = 0.002) were greater at d 30 than d 60, suggesting a greater proclivity for fatty acid biosynthesis and esterification by adipose tissue at d 30 of lactation. Although dietary lipid supplementation did not affect adipose tissue lipogenesis, results suggest that cows with a BCS of 4 at parturition have a greater propensity to deliver exogenously derived fatty acids to the adipocyte surface and incorporate preformed fatty acids into acylglycerols as stored adipocyte lipid. Additionally, cows in early lactation seemed to be able to synthesize and incorporate more fatty acids into stored lipid than cows during peak lactation.     

Conjugated linoleic acid content in adipose tissue of calves suckling beef cows on pasture and supplemented with raw or extruded soybeans

The concentration of CLA in adipose tissue can be increased in ruminants by feeding pasture and extruded soybeans. The objective of this study was to evaluate maternal supplementation of raw (RS) or extruded (ES) soybeans on the concentrations of CLA in milk fat of cows and s.c. adipose tissue of suckling calves. Thirty-two spring-calving cows (BW 624 +/- 76 kg; BCS 3.5 +/- 0.4; mean +/- SD) and calves (BW 127 +/- 15 kg) were separated into 2 groups. Cows were distributed to have 8 calves of each sex in both groups. When animals were turned out to pasture, dams received 2 kg/d of either RS or ES. Dietary treatments had no effect on average milk intake (P = 0.22) and pasture forage intake (P = 0.13) for calves over the course of the grazing season. As a result, no effect of treatments was observed on ADG (P = 0.26). At weaning, milk fat content of CLA reached 15.4 and 24.2 mg/g of total fatty acids for cows fed RS and ES, respectively (P = 0.02). The CLA concentrations in adipose tissue were 16.9 and 25.0 mg/g of total fatty acids for calves suckling dams fed RS and ES, respectively (P < 0.001). Overall, results demonstrated supplementing grazing cows with ES increased CLA content in milk and adipose tissue of suckling calves.     

Immune response and serum immunoglobulin G concentrations in beef calves suckling cows of differing body condition score at parturition and supplemented with high-linoleate or high-oleate safflower seeds

Two experiments were conducted to determine the effect of maternal lipid supplementation on the immune response to antigenic challenge in suckling calves. In Exp. 1, beginning 1 d postpartum, 18 primiparous crossbred beef cows were fed Foxtail millet hay and a low-fat (control) supplement or a supplement containing cracked, high-linoleate safflower seed in individual feeding stanchions until d 40 of lactation. The diets were formulated to provide similar quantities of N and TDN, and the linoleate diet was formulated to contain 5% of DMI as fat. Calves were injected s.c. with 15 mg of antigen (ovalbumin) at d 21 and again at d 35 of age. To measure the total serum antibody production in response to the antigen, blood samples were collected from the calves every 7 d via jugular venipuncture from d 14 to 42. Calves from linoleate-supplemented cows had a decrease (P = 0.04) in total antibody production in response to ovalbumin and appeared to have a delayed response to antigen challenge. Total antibody production increased (P < 0.001) after secondary exposure to ovalbumin. In Exp. 2, 36 Angus x Gelbvieh beef cows that were nutritionally managed to achieve a BCS of 4 or 6 at parturition were used to determine the effects of prepartum energy balance and postpartum lipid supplementation on the passive transfer of immunoglobulins and the immune response to antigenic challenge in their calves. Beginning at 3 d postpartum and continuing until d 60 of lactation, cows were fed hay and a low-fat control supplement or supplements consisting of either cracked, high-linoleate or high-oleate safflower seeds. Safflower seed supplements were formulated to provide 5% of DMI as fat. Calves were injected s.c. with 15 mg of ovalbumin at 21 d of age and again at 48 d of age. The antibody responses were determined in serum; cell-mediated immunity was assessed by intradermal antigen injection at 60 d of age. A trend was noted (P = 0.10) for calves suckling control-supplemented cows to have a greater response to antigen compared with calves from linoleate- and oleate-supplemented cows; however, no difference was observed among treatments (P = 0.86) in cell-mediated immune response. Postpartum oilseed supplementation in beef cows appears to decrease antibody production in response to antigenic challenge in suckling calves. However, BCS at parturition did not influence passive transfer of immunoglobulins in neonatal calves.     

Fatty acid indices of stearoyl-CoA desaturase do not reflect actual stearoyl-CoA desaturase enzyme activities in adipose tissues of beef steers finished with corn-, flaxseed-, or sorghum-based diets

We hypothesized that stearoyl-CoA desaturase (SCD) enzyme activity would not correlate with fatty acid indices of SCD activity in steers fed different grains. Forty-five Angus steers (358 +/- 26 kg BW) were individually fed for 107 d diets differing in whole cottonseed (WCS) supplementation (0, 5, or 15% of DM) and grain source (rolled corn, flaxseed plus rolled corn, or ground sorghum grain) in a 3 x 3 factorial arrangement. Flaxseed- and corn-fed steers had greater (P < 0.01) G:F (0.119 and 0.108, respectively) than sorghum-fed steers (0.093). Marbling score was decreased by WCS (P = 0.04), and LM area was decreased (P < 0.01) by sorghum. Plasma 14:0, 16:0, 16:1n-7, and 18:2n-6 were greatest in corn-fed steers, whereas plasma 18:3n-3 and 20:5n-3 were greatest in the flax-seed-fed steers (P < 0.01). Plasma 18:1trans-11 was least in sorghum-fed steers, and plasma cis-9,trans-11 CLA was barely detectable, in spite of high intestinal mucosal SCD enzyme activity (118 to 141 nmol*g tissue(-1).7 min(-1)). Interfascicular (i.f.) and s.c. cis-9,trans-11 CLA remained unchanged (P > or = 0.25) by treatment, although 18:1trans-11 was increased (P < or = 0.02) in steers fed corn or flaxseed. Steers fed flaxseed also had greater (P < 0.01) i.f. and s.c. concentrations of 18:3n-3 than steers fed the other grain sources. Oleic acid (18:1n-9) was least and total SFA were greatest (P < 0.01) in i.f. adipose tissue of steers fed 15% WCS. Lipogenesis from acetate in s.c. adipose tissue was greater (P < 0.01) in flaxseed-fed steers than in the corn- or sorghum-fed steers. Steers fed flaxseed or corn had larger i.f. mean adipocyte volumes (P < 0.01) than those fed sorghum and tended (P = 0.07) to have larger s.c. adipocyte volumes. Several fatty acid indices of SCD enzyme activity were decreased (P < or = 0.03) by WCS in i.f. adipose tissue, including the 18:2cis-9,trans-11/ 18:1trans-11 ratio. The 18:2cis-9,trans-11/18:1trans-11 ratio also tended to be decreased (P = 0.09) in s.c. adipose tissue by flaxseed; however, SCD enzyme activities in i.f. and s.c. adipose tissue were not affected by dietary WCS (P > or = 0.47) or grain source (P > or = 0.37). Differences in SFA seemed to be independent of SCD enzyme activity in both adipose tissues, suggesting that duodenal concentrations of fatty acids were more important in determining tissue fatty acid concentrations than endogenous desaturation by SCD.     

Feeding lambs high-oleate or high-linoleate safflower seeds differentially influences carcass fatty acid composition

Our objective was to determine effects of dietary high-oleate (Oleate; 76% 18:1) or high-linoleate (Linoleate; 78% 18:2) safflower seeds on fatty acids in muscle and adipose tissue of feedlot lambs. White-faced ewe lambs (n = 36) were fed a beet pulp, oat hay, and soybean meal basal diet (Control), blocked by BW, and allotted randomly to dietary treatments. Cracked safflower seeds were used in isocaloric and isonitrogenous replacement of beet pulp, oat hay, and soybean meal so that Oleate and Linoleate diets contained 5.0% additional fat. Fatty acids were determined in semitendinosus, longissimus dorsi (longissimus), and adipose tissue from the tail head (tailhead adipose tissue), adjacent to the 12th rib (s.c. adipose tissue), and kidney and pelvic fat (KPH adipose tissue) depots. Fatty acid data were analyzed within muscle and adipose tissue as a split-block design. Single degree of freedom orthogonal contrasts were used to compare treatment effects. Average daily gain, feed efficiency, and carcass characteristics did not differ (P = 0.15 to 0.96) across dietary treatments. Adipose tissue saturated fatty acids were greater (P = 0.04) for Controls but were not different (P = 0.36) in muscle. Trans-vaccenic acid (18:1(trans-11)) increased (P < 0.0001) with safflower supplementation and was greater (P < 0.0001) in Linoleate than in Oleate for both tissue types. Linoleate lamb had greater (P < 0.0001) PUFA than Oleate lamb in muscle and adipose tissue. Conjugated linoleic acids (CLA; cis-9, trans-11 and trans-10, cis-12) were greater (P < 0.0001) in muscle and adipose tissue of lambs fed safflower seeds. Lambs fed Linoleate had greater (P < 0.0001) CLA in adipose tissue and muscle than lambs fed Oleate. Saturated fatty acids were greater (P < 0.0001) in s.c. adipose tissue than in tailhead adipose tissue. Mono- and polyunsaturated fatty acids were greater (P < 0.0001) in tailhead adipose tissue than in s.c. adipose tissue. Weight percentages of 18:1(trans-11) ranked tailhead adipose tissue = KPH adipose tissue > s.c. adipose tissue and semitendinosus > longissimus, whereas CLA ranked tailhead adipose tissue > s.c. adipose tissue > KPH adipose tissue and semitendinosus > longissimus. Feeding mono- and polyunsaturated fatty acids increased tissue 18:1(trans-11) and CLA, which is a favorable change in regard to current human dietary guidelines.     

Effects of early- to mid-gestational undernutrition with or without protein supplementation on offspring growth, carcass characteristics, and adipocyte size in beef cattle

Angus × Gelbvieh cows with 2 to 3 previous pregnancies were used to evaluate effects of maternal nutrient restriction on offspring adipose tissue morphology at standard production endpoints. At 45 d after AI to a single sire, pregnancy was confirmed and cows randomly allotted into groups and fed a control (Con, 100% of NRC recommendations), nutrient-restricted (NR, 70% of Con diet), or nutrient-restricted + protein-supplemented (NRP, 70% of Con + essential AA supply to the small intestine equal to Con) diet. At d 185 of gestation, cows were commingled and received the Con diet thereafter. Bull calves were castrated at 2 mo of age. Calves were weaned at 210 d, backgrounded for 28 d, and then placed in the feedlot for 195 d. Steers and heifers were slaughtered at an average 12th-rib fat thickness of 7.6 mm. Adipose tissue from selected depots was collected for adipocyte size analysis. There was no significant difference in BW or BCS between Con, NRP, and NR cows at d 45 of gestation, which averaged 489.7 ± 17.7 kg and 5.35 ± 0.13, respectively. At d 185 of gestation, Con and NRP groups had similar BW (566.1 ± 14.8 and 550.2 ± 14.8 kg) and BCS (6.34 ± 0.27 and 5.59 ± 0.27), but NR cows exhibited reduced (P < 0.05) BW (517.9 ± 14.8 kg) and BCS (4.81 ± 0.27). Among offspring (steers and heifers) at slaughter, there were no significant differences in BW or organ weights among treatment groups. Yield grade was reduced (P < 0.05) and semitendinosus weight/HCW tended (P = 0.09) to be reduced in NR offspring compared with Con and NRP offspring. Average adipocyte diameter was increased (P < 0.05) in subcutaneous, mesenteric, and omental adipose tissue and tended (P = 0.09) to increase in perirenal adipose tissue in NR compared with Con offspring with NRP offspring adipocyte diameter being either intermediate or similar to Con calves. The adipocyte size alterations observed in NR offspring were confirmed by DNA concentration of the adipose tissue depots. There also was an increased mRNA expression (P < 0.05) of fatty acid transporter 1 in subcutaneous adipose tissue from NR offspring compared with Con and NRP offspring. Nutritional restriction during early and mid gestation increased or tended to increase (P < 0.09) adipocyte diameter in all adipose tissue depots in finished steer and heifer calves.     

Effects of body condition score at parturition and postpartum supplemental fat on metabolite and hormone concentrations of beef cows and their suckling calves

To determine the effects of BCS at parturition and postpartum lipid supplementation on blood metabolite and hormone concentrations, 3-yr-old Angus x Gelbvieh beef cows, which were nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of BW) at parturition, were used in a 2-yr experiment (n = 36/yr). Beginning at 3 d postpartum, cows within each BCS were assigned randomly to be fed hay and a low-fat control supplement or lipid supplements with either cracked high-linoleate or high-oleate safflower seeds until d 61 of lactation. The diets were formulated to be isonitrogenous and isocaloric, and the safflower seed supplements were formulated to achieve 5% DMI as fat. On d 31 and 61 of lactation, blood samples were collected preprandially and then hourly postprandially (at 0, 1, 2, 3, and 4 h). Serum insulin (P = 0.27) and glucose (P = 0.64) were not affected by BCS at parturition. The mean concentrations of plasma NEFA (P = 0.08) and beta-hydroxybutyrate (P = 0.08) tended to be greater, and serum IGF-I was greater (P < 0.001) in BCS 6 than BCS 4 cows. Conversely, serum GH was greater (P = 0.003) for BCS 4 cows, indicating that regulation of IGF by GH may have been uncoupled in BCS 4 cows. The postpartum diet did not affect NEFA (P = 0.94), glucose (P = 0.15), IGF-I (P = 0.33), or GH (P = 0.62) concentrations. Oleate-supplemented cows had greater (P = 0.03) serum insulin concentrations, whereas control cows had greater (P = 0.01) plasma beta-hydroxybutyrate concentrations. Concentrations of NEFA (P = 0.05) and glucose (P < 0.001) were greater, and beta-hydroxybutyrate tended (P = 0.07), to be greater at d 3, whereas serum IGF-I was greater (P = 0.003) at d 6 of lactation. Similar concentrations of NEFA, glucose, GH, and IGF-I indicate that the nutritional status of beef cows during early lactation was not influenced by lipid supplementation. However, perturbations of the somatotropic axis in BCS 4 cows indicate that the influence of energy balance and BCS of the cow at parturition on postpartum performance should be considered when making managerial decisions.     

Body condition score at parturition and postpartum supplemental fat effects on cow and calf performance

Three-year-old Angus x Gelbvieh beef cows nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of BW) at parturition were used in a 2-yr experiment (n = 36/yr) to determine the effects of prepartum energy balance and postpartum lipid supplementation on cow and calf performance. Beginning 3 d postpartum, cows within each BCS were assigned randomly to be fed hay and a low-fat control supplement or supplements with either high-linoleate cracked safflower seeds or high-oleate cracked safflower seeds until d 60 of lactation. Diets were formulated to be isonitrogenous and isocaloric, and safflower seed supplements were provided to achieve 5% of DMI as fat. Ultrasonic 12th rib fat and LM area were lower (P < 0.001) for cows in BCS 4 compared with BCS 6 cows throughout the study. Cows in BCS 4 at parturition maintained (P = 0.02) condition over the course of the study, whereas cows in BCS 6 lost condition. No differences (P = 0.44 to 0.71) were detected for milk yield, milk energy, milk fat percentage, or milk lactose percentage because of BCS; however, milk protein percentage was less (P = 0.03) for BCS 4 cows. First-service conception rates did not differ (P = 0.22) because of BCS at parturition, but overall pregnancy rate was greater (P = 0.02) in BCS 6 cows. No differences (P = 0.48 to 0.83) were detected in calf birth weight or ADG because of BCS at parturition. Dietary lipid supplementation did not influence (P = 0.23 to 0.96) cow BW change, BCS change, 12th rib fat, LM area, milk yield, milk energy, milk fat percentage, milk lactose percentage, first service conception, overall pregnancy rates, or calf performance. Although cows in BCS of 4 at parturition seemed capable of maintaining BCS during lactation, the overall decrease in pregnancy rate indicates cows should be managed to achieve a BCS >4 before parturition to improve reproductive success.     

The fatty acid composition of muscle fat and subcutaneous adipose tissue of grazing heifers supplemented with plant oil-enriched concentrates

Our objective was to determine the effect of oil supplementation of pasture fed, beef cattle on the fatty acids, particularly CLA and PUFA, of muscle and s.c. adipose tissue. Forty-five Charolais crossbred heifers were blocked on BW and randomly assigned to 1 of 3 dietary regimens in a randomized complete block design (n = 15). The 3 treatments were: unsupplemented grazing (GO), restricted grazing plus a sunflower oil-enriched ration (SO), or restricted grazing plus a linseed oil-enriched ration (LO). Heifers were fed the experimental diets for approximately 158 d. Samples of LM muscle and s.c. adipose tissue were taken postmortem, the muscle fat was separated into neutral lipid and polar lipid (no separation was performed on the s.c. adipose tissue), and the fatty acid profile was determined by GLC. No effect of dietary treatment on carcass weight or total fatty acid concentration (mean 2,571 mg/100 g of muscle) in muscle fat was detected. Heifers offered SO had a greater (P < 0.001) proportion of CLA and C18:1trans-11 (1.90 and 9.35 vs. 1.35 and 6.89 g/100 g of fatty acids, respectively) in neutral lipid of muscle fat compared with those offered LO, which had a greater proportion of CLA and C18:1trans-11 than heifers offered GO (0.78 and 3.37 g/100 g of fatty acids, respectively). Similar effects were observed in the polar lipid and s.c. lipid. The PUFA:SFA ratio was greater in muscle fat and s.c. adipose tissue from supplemented heifers than in those offered GO (P < 0.001). Compared with LO, the PUFA:SFA ratio was greater (P < 0.05) in muscle fat of heifers offered SO, but there was no difference between SO and LO for this ratio in s.c. adipose tissue. The n-6:n-3 PUFA ratio was similar in muscle and s.c. adipose tissue for GO and LO, but it was greater (P < 0.05) for SO. It is concluded that supplementation of pasture-fed cattle with plant oil-enriched concentrates resulted in an increase in beef fat of some fatty acids considered to be of benefit to human health. Concentrates enriched with sunflower oil were more effective in increasing the CLA concentration, whereas linseed oil-enriched concentrates resulted in a more favorable n-6:n-3 PUFA ratio. The relevance to human health of the associated increase in C18:1trans-11 merits investigation.     

Plasma mineral and energy metabolite concentrations in dairy cows fed an anionic prepartum diet that did or did not have retained fetal membranes after parturition

OBJECTIVE: To compare plasma total calcium, phosphorus, magnesium, nonesterified fatty acids (NEFA), beta hydroxy butyrate (BHB), and glucose concentrations in parturient dairy cows that were fed an anionic prepartum diet between those with and without retained fetal membranes (RFM) at 24 hours after parturition. ANIMALS: 152 Holstein cows that calved during October through December of 1997 PROCEDURE: All cows were fed an anionic prepartum diet. Blood sample was taken within 6 hours after parturition from randomly selected cows. Thirty-nine cows had a diagnosis of RFM at 24 hours after parturition; 113 were not affected with RFM. At calving, body condition score (BCS; 1 [thin] to 5 [obese]), parity, and calving difficulty score were recorded. Plasma calcium, phosphorus, magnesium, NEFA, BHB, and glucose concentrations were compared between cows with or without RFM. RESULTS: Cows with RFM had significantly lower plasma calcium concentration soon after calving, compared with cows without RFM. Cows with a parity of > or = 3 had significantly lower plasma concentrations of calcium and higher concentrations of magnesium, compared with cows with a parity of 1 or 2. Cows with a BCS of > or = 3.25 at calving had significantly higher plasma concentrations of BHB than cows with a BCS of 2.75 to 3.0. Cows with dystocia had significantly higher plasma concentrations of glucose, compared with cows without dystocia. CONCLUSIONS AND CLINICAL RELEVANCE: In parturient cows fed a prepartum anionic diet, those with RFM have lower plasma calcium concentrations than cows without RFM, although this association does not prove a cause-effect relationship.     

Feeding flaxseed in grass hay and barley silage diets to beef cows increases alpha-linolenic acid and its biohydrogenation intermediates in subcutaneous fat

The objective of the study was to determine temporal fat deposition and fatty acid profiles in beef cows fed hay- or barley silage-based diets, with or without flaxseed. Crossbred cull beef cows (n = 64, >30 mo of age, 620 ± 5 kg) were removed from grassland pastures, randomly assigned to 16 pens, and given ad libitum access to 50:50 (wt/wt, DM basis) forage:concentrate diets containing 0 or 15% ground flaxseed (DM basis, 5.2% added fat). Diets consisted of hay control (HC), hay+flaxseed (HF), barley silage control (SC), and silage+flaxseed (SF). Backfat biopsies were obtained from each cow at 0, 6, and 12 wk, and at slaughter (~20 wk) to assess fatty acid composition. With the exception of feed efficiency, flaxseed × forage interactions were not significant for backfat accumulation or performance parameters. Flaxseed improved (P < 0.01) feed conversion when supplemented to hay-based diet and increased ADG (P = 0.03), resulting in a heavier (P = 0.02) BW. Compared with hay, barley silage increased (P < 0.01) DMI, ADG, and feed efficiency. Subcutaneous fat contained 0.68% n-3 fatty acids at wk 0, and reached 0.68, 0.81, and 0.94% in HF cows after 6, 12, and 20 wk, respectively (Y(n-3) = 0.0133X + 0.6491, r = 0.87). It was 0.67% at wk 0, and reached 0.65, 0.77, and 0.90% in SF cows after 6, 12, and 20 wk, respectively (Y(n-3) = 0.0121X + 0.6349, r = 0.75). In contrast, weight percentage of n-3 fatty acids decreased in HC cows from 0.63, 0.50, and 0.47, to 0.43%, and in SC cows from 0.63, 0.40, and 0.36, to 0.33% over the 20 wk. A forage × flaxseed interaction (P < 0.05) occurred for many of the α-linolenic acid (ALA) biohydrogenation intermediates, including vaccenic acid (C18:1 trans-11) and CLA (combined C18:2 trans-7,cis-9 and cis-9,trans-11) in plasma, and in subcutaneous fat this also included non-CLA dienes. Concentrations of most α-linolenic acid biohydrogenation intermediates were greater when feeding flaxseed with hay. In conclusion, forage source altered plasma concentrations and rate of accumulation of ALA biohydrogenation products in subcutaneous fat from beef cows fed flaxseed. Factors responsible for this response are yet to be defined, but may include forage-mediated changes in ruminal biohydrogenation of ALA, as well as alterations in fatty acid metabolism and deposition.     

Corn oil supplementation to steers grazing endophyte-free tall fescue. II. Effects on longissimus muscle and subcutaneous adipose fatty acid composition and stearoyl-CoA desaturase activity and expression

Eighteen steers were used to evaluate the effect of supplemental corn oil level to steers grazing endophyte-free tall fescue on fatty acid composition of LM, stearoyl CoA desaturase (SCD) activity and expression as well as cellularity in s.c. adipose. Corn oil was supplemented (g/kg of BW) at 0 (none), 0.75 (medium), and 1.5 (high). Cottonseed hulls were used as a carrier for the corn oil and were supplemented according to pasture availability (0.7 to 1% of BW). Steers were finished on a rotationally grazed, tall fescue pasture for 116 d. Fatty acid composition of LM, s.c. adipose, and diet was determined by GLC. Total linoleic acid intake increased linearly (P < 0.01) with corn oil supplementation (90.7, 265.1, and 406.7 g in none, medium, and high, respectively). Oil supplementation linearly reduced (P < 0.05) myristic, palmitic, and linolenic acid percentage in LM and s.c. adipose. Vaccenic acid (C18:1 t11; VA) percentage was 46 and 32% greater (linear, P = 0.02; quadratic, P = 0.01) for medium and high, respectively, than none, regardless of tissue. Effect of oil supplementation on CLA cis-9, trans-11 was affected by type of adipose tissue (P < 0.01). In the LM, CLA cis-9, trans-11 isomer was 25% greater for medium than for none and intermediate for high, whereas CLA cis-9, trans-11 CLA isomer was 48 and 33% greater in s.c. adipose tissue for medium and high than for none, respectively. Corn oil linearly increased (P 0.05) the percentage of total SFA, MUFA, or PUFA but linearly increased (P = 0.03) n-6:n-3 ratio from 2.4 to 2.9 in none and high, respectively. Among tissues, total SFA and MUFA were greater in s.c. adipose than LM, whereas total PUFA, n-6, and n-3 fatty acids and the n-6:n-3 ratio were lower. Trans-10 octadecenoic acid, VA, and CLA trans-10, cis-12 were greater (P < 0.01) in s.c. adipose than in LM. Oil supplementation did not alter (P > 0.05) stearoyl CoA desaturase activity or mRNA expression. Corn oil supplementation to grazing steers reduced the percentages of highly atherogenic fatty acids (myristic and palmitic acids) and increased the percentages of antiatherogenic and anticarcinogenic fatty acids (VA and cis-9, trans-11 CLA).     

Chemical and sensory properties of beef of known source and finished on wet distillers grains diets containing varying types and levels of roughage

Beef knuckles (n = 160) were obtained from source-verified cattle finished on 30% wet distillers grains plus solubles enriched with varying levels of alfalfa hay (4 or 8%), corn silage (6 or 12%), or corn stalks (3 or 6%) based on NDF. Proximate analysis, pH, oxidation-reduction potential, fatty acid composition, and sensory analysis were conducted on the rectus femoris muscle to determine if roughage inclusion, in conjunction with wet distillers grains plus solubles and cattle source, affects beef flavor with particular interest in liver-like off-flavor. Proximate analysis, fat content, and oxidation-reduction potential were unaffected (P ge;0.129) by diet or source. For s.c. adipose tissue, cattle from Nebraska (NE) had greater amounts of MUFA (P = 0.048) and unsaturated fatty acids (P = 0.068) but less SFA (P = 0.065) when compared with cattle from South Dakota. Diet affected s.c. adipose tissue levels of 15:0, 17:0, and n-3 fatty acids in which cattle from NE finished on the low corn stalk diet had (P < or =0.050) lower levels. Cattle from NE had (P < or = 0.049) greater i.m. adipose proportions of 13:0 and CLA. Dietary effects (P < or = 0.050) were observed for i.m. adipose tissue proportions of 16:0, 18:1(n-9), 18:2(n-6), 20:4(n-6), 22:5(n-3), MUFA, PUFA, and n-6 fatty acids. Sensory analysis revealed that cattle from NE were (P < or = 0.023) less juicy and had less bloody notes when compared with cattle from South Dakota. Cattle finished on the low alfalfa diet were (P < or = 0.014) more tender and juicy but had more bloody notes. No (P ge; 0.670) dietary or source effects were noted for liver-like off-flavor. Subcutaneous amounts of 18:2(n-6 trans) (r = -0.17) were inversely related to the incidence of liver-like off-flavor, whereas 20:1(n-9) (r = 0.21), CLA cis-9, trans-11 (r = 0.16) were directly related. Data from this study indicate that type and level of roughage inclusion and cattle source have minimal effects on fatty acid profiles and sensory properties of the musculus rectus femoris. However, individual fatty acids of s.c. and i.m. adipose tissue were significantly correlated with liver-like off-flavor.     

Effect of indoor energy restriction level and management on beef production in Belgian Blue double‐muscled cow‐calf pairs

One hundred and twenty‐six cows were involved to investigate the impact of energy (E) restriction (100%, 90%, 80% and 70% of total energy requirements) during the indoor period and two calf management systems (CMS: suckling or rearing). An E restriction during the indoor period resulted in a loss of body weight, even for E100, which was compensated during the re‐alimentation period, but body weight remained lower in suckling than in non‐suckling cows. The cows yielded 213 full‐term gestations and 8 abortions. Abortion was not affected by E (p = 0.187) or CMS (p = 0.804). Calving interval was neither affected by E (p = 0.775) but tended to be longer in suckled cows (p = 0.087). E reduced body weight and body condition score (BCS) at the end of the calving interval, while CMS only affected BCS. E70 resulted in a higher colostrum yield than E100 and E 90 but immunoglobulin content was not affected (p = 0.759). Cow culling was not affected by E or CMS. It increased from 12.9% to 22.2% and 32.5% for cows with a BCS at parturition lower than 1.5 or between 1.5 and 2.0, or higher than 2 respectively. Calf birth weight was neither affected by E or CMS, but there was an interaction between E and dam age (p = 0.050). Increasing the E restriction tended to reduce calf survival (p = 0.089). Performance of the surviving calves was not affected by E, but suckling calves gained faster than rearing calves (p < 0.001). Beef production by the cow‐calf pair was not different between energy levels (p = 0.738), but it was 10.8% lower for E70 than for E100 cows. It is not appropriate to apply an E restriction of more than 10–20% for maximum cow reproductive traits and calf performance.     

Comparison of muscle fatty acid profiles and cholesterol concentrations of bison,beef cattle,elk, and chicken

The objective of this study was to compare fatty acid weight percentages and cholesterol concentrations of longissimus dorsi (LD), semitendinosus (ST), and supraspinatus (SS) muscles (n = 10 for each) of range bison (31 mo of age), feedlot-finished bison (18 mo of age), range beef cows (4 to 7 yr of age), feedlot steers (18 mo of age), free-ranging cow elk (3 to 5 yr of age), and chicken breast. Lipids were analyzed by capillary GLC. Total saturated fatty acids (SFA) were greater (P < 0.01) in range bison than in feedlot bison and were greater (P < 0.01) in SS of range beef cattle than in feedlot steers. Muscles of elk and range bison were similar (P > 0.05) in SAT. In LD, polyunsaturated fatty acids (PUFA) were highest (P < 0.01) for elk and range bison and lowest (P < 0.01) for feedlot steers within each muscle. Range bison and range beef cows had greater (P < 0.01) PUFA in LD and ST than feedlot bison or steers, respectively. Range-fed animals had higher (P < 0.01) n-3 fatty acids than feedlot-fed animals or chicken breast. Chicken breast n-6 fatty acids were greater (P < 0.01) than for muscles from bison, beef, or elk. Elk had higher (P < 0.01) n-6 fatty acids than bison or beef cattle; however, range-fed animals had higher (P < 0.01) n-6 fatty acids than feedlot-fed animals in ST. Conjugated linoleic acid (CLA, 18:2cis-9, trans-11) in LD was greatest (P < 0.01) for range beef cows (0.4%), and lowest for chicken breast and elk (mean = 0.1%). In ST, CLA was greatest (P < 0.01) for range and feedlot bison and range beef cows (mean = 0.4%) and lowest for elk and chicken breast (mean = 0.1%). Also, SS CLA was greatest (P < 0.01) for range beef cows (0.5%) and lowest for chicken breast (0.1%). Mean total fatty acid concentration (g/100 g tissue) for all muscles was highest (P < 0.01) for feedlot bison and feedlot cattle and lowest (P < 0.01) for range bison, range beef cows, elk, and chicken. Chicken breast cholesterol (mg/100 g tissue) was higher (P < 0.01) than LD and ST cholesterol, which were lowest (P < 0.01; 43.8) for range bison and intermediate for the other species. Cholesterol in SS was highest (P < 0.01) for feedlot bison and steers, which were similar to chicken breast (mean = 61.2 vs 52.8 for the mean of the other species). We conclude that lipid composition of bison muscle varies with feeding regimen, and range-fed bison had muscle lipid composition similar to that of forage-fed beef cows and wild elk.     

Effects of breed type and restricted versus ad libitum feeding on fatty acid composition and cholesterol content of muscle and adipose tissue from mature bovine females

Fatty acid composition and cholesterol content of muscle and adipose tissue from mature cows (N = 101) representing 15 breeds and crosses were determined. An initial group of cows was slaughtered after being fed slightly above the maintenance level for 2 wk; the remaining cows were fed either at the maintenance level or ad libitum for 84 d, then slaughtered. Samples of triceps brachii and longissimus muscle and subcutaneous and perinephric adipose tissue were obtained from each carcass. In addition, phospholipid and triacylglycerol fatty acids from total lipid extracts of triceps brachii muscle and subcutaneous adipose tissue were analyzed for 24 cows that were fed ad libitum or at the maintenance level for 84 d. Breed type effects on fatty acid composition were more pronounced in adipose tissue than in muscle tissue. Total lipid extracts of both triceps brachii and longissimus muscle from animals fed a maintenance diet for 84 d contained higher (P less than .01) percentages (3 to 8%) of polyunsaturated fatty acids (PUFA) and lower percentages (2 to 3%) of saturated fatty acids (SFA) than those from animals fed ad libitum for 84 d. This reflected significant variation in the fatty acids C14:0, C16:0, C18:2, C18:3 and C20:4 for both longissimus and triceps brachii muscle. Fatty acid composition within phospholipid and triacylglycerol fractions was similar regardless of maintenance or ad libitum feeding. Much of the variation in total lipid fatty acid composition appeared to be the result of differences in triacylglycerol:phospholipid ratios. Adipose tissue contained about twice as much cholesterol (mg/100 g wet weight) as muscle tissue. Both breed type and feeding group effects on cholesterol content of muscle tissue were nonsignificant. Values for cholesterol content of adipose tissue from cows fed restricted diets were higher than those from cows fed ad libitum (approximately 55 mg/100 g higher for subcutaneous and 25 mg/100 g for perinephric). The results show that changes in fatty acid composition of bovine tissues can be made genetically and by varying the energy level in the diet. Alteration of the cholesterol content of muscle tissue by these methods does not appear to be feasible.     

Influence of nutrient intake and body fat on concentrations of insulin-like growth factor-I, insulin, thyroxine, and leptin in plasma of gestating beef cows

Pregnant Angus x Hereford cows (n = 73) were used to determine the effects of amount of nutrient intake and BCS on concentrations of IGF-I, insulin, leptin, and thyroxine in plasma. At 2 to 4 mo of gestation, cows were blocked by BCS and assigned to one of four nutritional treatments: high (H = a 50% concentrate diet fed ad libitum in a drylot) or adequate native grass pastures and one of three amounts of a 40% CP supplement each day (M = moderate, 1.6 kg; L = low, 1.1 kg; or VL = very low, 0.5 kg; as-fed basis). After 110 d of treatment, all cows grazed dormant native grass pasture and received 1.6 kg/d of a 40% CP supplement. At 68, 109, and 123 d of treatment, cows were gathered, and plasma samples were collected by tail venipuncture (fed sample). After 18 h without feed and water, a second plasma sample was collected (fasted sample). At 109 d of treatment, BCS was greatest (P < 0.05) for H cows, similar for M and L cows, and least for VL cows. Concentrations of insulin and leptin were greater (P < 0.05) for H cows than for M and VL cows at 68 and 109 d, but similar for all groups at 123 d. Thyroxine in plasma was greatest (P < 0.05) for H cows at 68 d and similar for cows on all treatments at 123 d. Concentrations of IGF-I, insulin, and leptin in fed and fasted cows were positively correlated with BCS at 109 d. Body condition was predictive of concentrations of IGF-I, insulin, and leptin when cows had different nutrient intakes, but BCS accounted for less than 12% of the variation in plasma concentrations of IGF-I, insulin, and leptin when nutrient intake was the same for all cows. We conclude that amount of nutrient intake has a greater influence than body energy reserves on IGF-I, insulin, and leptin concentrations in the plasma of gestating beef cows.