FATTY ACID COMPOSITION OF BOVINE INTRAMUSCULAR AND SUBCUTANEOUS FAT AS RELATED TO BREED AND SEX

Effect of an essential oils blend on meat characteristics of crossbred heifers finished on a high-grain diet in a feedlot

Context Natural additives have been studied to increase animal performance and the quality of meat as alternatives to the use of antibiotics. Aims The present work investigated the effects of an essential oil blend (oregano, rosemary, lemon, garlic, eucalyptus, thyme and sweet orange) incorporated into the diet of crossbred heifers on the meat quality. Methods Thirty 12-month-old half-sister crossbred heifers (1/2 Angus vs 1/2 Nellore) with an average weight of 219.8 ± 8.8 kg were allocated in individual pens for 3 months. Three diets were tested: E0.0 (without the essential oil blend); E3.5 (with 3.5 g of the essential oil blend/animal.day); E7.0 (7.0 g of the essential oil blend/animal.day). The fatty acid composition (chemical) and profile of the Longissimus muscle were evaluated. In addition, the effect of aging (1, 7 and 14 days in vacuum packs at 2°C) on the colour, cooking and thawing losses, texture, and lipid oxidation were determined. Key results The essential oil blend did not affect (P > 0.05) the meat. It did not impact on the decrease in shear force, increased lipid oxidation or changes in colour with aging. Conclusions The chemical composition, water holding capacity, shear force, lipid oxidation, and fatty acid profile were not influenced by including the essential oil blend in the diet of heifers. Implications The use of low dosages of an essential oil blend could be applied in the diet of heifers, without affecting meat quality.

Short communication: Association of milk fatty acids with early lactation hyperketonemia and elevated concentration of nonesterified fatty acids

The objective of our study was to extend the limited research available on the association between concentrations of milk fatty acids and elevated nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) concentrations in early lactation dairy cattle. Measurement of milk fatty acids for detection of cows in excessive negative energy balance has the potential to be incorporated in routine in-line monitoring systems. Blood samples were taken from 84 cows in second or greater lactation 3 times per week between 3 to 14 d in milk. Cows were characterized as hyperketonemic (HYK) if blood BHB concentration was ≥1.2mmol/L at least once and characterized as having elevated concentrations of NEFA (NEFAH) if serum NEFA concentration was ≥1mmol/L at least once. Composition of colostrum and milk fatty acids at wk 2 postpartum was used to investigate the potential diagnostic value of individual fatty acids and fatty acid ratios for the correct classification of cows with NEFA and BHB concentrations above these thresholds, respectively. Receiver operating characteristic (ROC) curves were used to identify thresholds of fatty acid concentration and fatty acid ratios when ROC area under the curve was ≥0.70. Correct classification rate (CCR, %) was calculated as {[(number of true positives + number of true negatives)/total number tested] × 100}. None of the colostrum fatty acids yielded a sufficiently high area under the curve in ROC analysis for the association with HYK and NEFAH. The following fatty acids and fatty acid ratios were identified for an association with NEFAH (threshold, CCR): C15:0 (≤0.65g/100g, 68.3%); cis-9 C16:1 (≥1.85g/100g, 70.7%); cis-9 C18:1 (≥26g/100g, 69.5%), cis-9 C18:1 to C15:0 ratio (≥45, 69.5%); cis-9 C16:1 to C15:0 (≥2.50, 73.2%). Several fatty acids were associated with HYK (threshold, CCR): C6:0 (≤1.68g/100g, 80.5%), C8:0 (≤0.80g/100g, 80.5%), C10:0 (≤1.6g/100g, 79.3%); C12:0 (≤1.42g/100g, 82.9%); C14:0 (≤6.10g/100g, 84.1%); C15:0 (≤0.50g/100g, 82.9%), cis-9 C18:1 (≥30g/100g, 81.7%). The use of fatty acid ratios did not improve CCR over using individual fatty acids for the classification of HYK. Colostrum fatty acid composition was not useful in predicting NEFAH or HYK between 3 to 14 d in milk. Accuracy of milk fatty acids and fatty acid ratios to correctly classify cows with elevated concentrations of NEFA and BHB between 3 to 14 d in milk was moderate and overall higher for HYK. Determining changes in the fatty acid composition of milk fat from milk samples at wk 2 postpartum for the detection of cows with elevated concentrations of BHB and NEFA can currently not be recommended to replace direct measurement. Future applications should target repeated milk sampling between 3 to 14 d in milk to identify the best sampling for determination of milk fatty acid composition within the first 2 wk postpartum.

Fatty acid content and composition of UK beef and lamb muscle in relation to production system and implications for human nutrition

Although ruminant meats normally have a low ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (P:S ratio), the muscle contains a range of C(20) and C(22) PUFA of both the n-6 and n-3 series of potential significance in human nutrition. However, information on the amounts of these fatty acids in muscle and how they are modified by production system is limited In this study, the content and composition of fatty acids was determined in several muscles from beef steers fed grass (grazed) and bulls fed cereal concentrates. These are the two main types of beef production in the UK and Europe. Muscle fatty acids were also determined in lambs fed grass (grazed on pasture). The total fatty acid content of all muscles studied was less than 35 g kg(-1). The percentages in total fatty acids of all n-3 PUFA were higher in muscles from steers fed grass than from bulls fed concentrates whereas all n-6 PUFA were higher in the latter. The gluteobiceps muscle contained the largest amounts of fatty acids including PUFA and the m. longissimus dorsi the least amounts of PUFA in beef and lamb, and m. longissimus contained the lowest percentages of PUFA. Arachidonic acid was the major fatty acid in the C(20) + C(22) PUFA in beef from both production systems with twice as much in muscles from bulls fed concentrates. The P:S ratios were higher in the latter animals, range 0.21-0.34 compared with 0.08-0.13 in the steers fed grass. However, the n6:n-3 ratio was much less desirable in the bulls, 15.6-20.1 compared with 2.0-2.3 in the steers fed grass. These effects of production system in ruminants are larger than previously reported. Lamb muscle P:S ratios resembled those in grass-fed beef but the n-6:n-3 ratios were lower. The percentage of trans unsaturated 18:1 fatty acids was similar in both cattle production systems but lamb muscles contained twice as much as beef. Although the concentrations of the C(20) and C(22) PUFA are much lower than in fish, maintaining high n-3 levels in ruminant meats through grass feeding may be advantageous in human nutrition since meat is more widely consumed.

A comparison of fat composition of Japanese and long-term grain-fed Australian steers

Subcutaneous and intermuscular fat samples were collected from carcases of four major breeds of steers in Japan: Wagyu, Wagyu × Angus, Dairy and Murray Grey. For comparison, we also collected subcutaneous fat samples from carcases of long-term grain-fed (350-455 days) Angus, Jersey and Angus × Hereford steers, and short-term grain-fed (70-100 days) Murray Grey steers in Australia. Fatty acid profiles were determined on all samples and triacylglycerol composition, thermal properties, fat cell size and lipid and connective tissue contents were determined on representative samples. Compared with the Japanese samples which were soft to very soft when assessed subjectively, samples of Australian fat were generally hard and somewhat fibrous in appearance. These tactile and visual differences in the hardness of the subcutaneous fat between the Japanese and Australian beef were confirmed by the physical and chemical properties determined. Markedly different melting patterns were observed for the Australian and Japanese fat samples. The Japanese fat had considerably less saturated and more unsaturated fatty acids resulting in much higher unsaturated/saturated ratios (1.9) compared with the Australian samples (1.0). This resulted primarily from the high contents of oleic and palmitoleic acids and the low content of stearic acid of the Japanese samples. The triacylglycerols from the Japanese fat had considerably less tri-saturated and di-saturated fatty acids and more di-monounsaturated and tri-monounsaturated fatty acids in their structure. Differences were observed when the Japanese subcutaneous fat samples were grouped by their meat quality grades. From Grade 5 to Grade 2, there was a significant decrease in marbling score (9.3 to 2.5) and in the ratio of palmitoleic to stearic acid (1.7 to 1.2) and an increase in the connective tissue content (1.5 to 2.1%). Compared with subcutaneous fat, intermuscular fat had a higher content of saturated and a lower content of unsaturated fatty acids resulting in a lower ratio of unsaturated to saturated fatty acids and of palmitoleic to stearic acid. It was concluded that the fatty acid composition and the triacylglycerol structure of fat plays the predominant role in determining the lustre, texture and properties of fat desired by the Japanese market: the soft character of fat from Japanese cattle results primarily from its low content of stearic acid and consequent lower melting temperatures. Fat cell size and the lipid and connective tissue contents of fat appear to be less important.

Interrelation of fatty acid composition in adipose tissue, serum, and liver of dairy cows during the development of fatty liver postpartum

We investigated the composition of fatty acids in adipose tissue, serum, and liver of cows that were fed at restricted energy intake or were overfed during the dry period. Overfed cows had higher concentrations of serum nonesterified fatty acids and consequently accumulated greater amounts of triacylglycerols in the liver than did cows that were fed at restricted energy intake. The percentages of the different fatty acids present in adipose tissue were similar for both groups and did not change during sampling intervals. Before parturition, concentrations of the individual fatty acids present in serum were similar between groups. After parturition, concentrations of major fatty acids in serum, including palmitic, stearic, oleic, and linoleic acids significantly increased in both groups and were higher in overfed cows than in cows that were fed at restricted energy intake. The shift of concentrations of the different fatty acids present in the liver--as a result of increased lipolysis-was observed in palmitic, oleic, and linoleic acids but not stearic acid, suggesting that stearic acid is used by the liver (i.e., oxidation) or is considerably secreted through the milk, thereby not increasing in accumulation in the liver. In conclusion, different feeding regimens during the dry period do not influence the composition of fatty acids in adipose tissue. More intensive lipolysis results in increased concentrations of palmitic, stearic, oleic, and linoleic acids in the blood; subsequently, these fatty acids, excluding stearic acid, greatly accumulated in the liver.

Delta9 desaturase activity in bovine subcutaneous adipose tissue of different fatty acid composition

Two experiments were conducted to investigate the relationship between delta9 desaturase (stearoyl-coenzyme A desaturase) activity and fatty acid composition in subcutaneous adipose tissue from cattle of different backgrounds. In Experiment 1, subcutaneous adipose tissue samples were taken from carcasses of pasture-fed cattle and feedlot cattle fed for 100, 200, or 300 d. Adipose tissue from pasture-fed cattle had significantly lower total saturated fatty acids and higher total unsaturated fatty acids than feedlot cattle. Desaturase activity correspondingly was 60-85% higher in pasture-fed cattle than in feedlot cattle. There was no difference in the fatty acid composition or desaturase activity among samples from the 100-, 200-, and 300-d feedlot cattle. In Experiment 2, adipose tissue samples were collected from carcasses of feedlot cattle fed for 180 d with either a standard feedlot ration (control group), or a ration containing rumen-protected cottonseed oil (CSO) for the last 70-80 d. Adipose tissue from the CSO-fed cattle was more saturated than that from the control group, having significantly more 18:0 and less 16:1 and 18:1. Correspondingly, adipose tissue from the CSO group had significantly lower desaturase activity. The elevated 18:2 in adipose tissue from the CSO group confirmed that unsaturated fatty acids (including cyclopropenoid fatty acids) were protected from biohydrogenation. Further studies are needed to determine whether the repression of desaturase activity results from direct inhibition by cyclopropenoic acids or by higher dietary contents of 18:2.

Hepatic fatty acid composition in periparturient dairy cows with fatty liver induced by intake of a high energy diet in the dry period

The present study compared the hepatic fatty acid composition of cows that were fed a high energy diet during the dry period to induce fatty liver after parturition with that of control cows. Treated cows had higher concentrations of plasma nonesterified fatty acids as a result of greater lipolysis after parturition than did control cows; consequently, the treated cows accumulated greater amounts of triacylglycerols in the liver. Before parturition, treated cows had lower percentages of oleic acid and higher percentages of linoleic acid than did control cows, but percentages of other fatty acids were similar for both groups. After parturition, percentages of each fatty acid were changed substantially, particularly the four major fatty acids (palmitic, stearic, oleic, and linoleic acids). For treated cows, the percentages of palmitic and oleic acids were higher at 0.5 wk after parturition than at 1 wk before parturition; percentages of stearic and linoleic acids decreased. Unlike treated cows, the percentages of both oleic and linoleic acids in the control cows did not change during that time. Moreover, we found that when lipolysis decreased, as indicated by lower plasma nonesterified fatty acid concentrations, the percentages of each fatty acid gradually rebounded toward the concentrations measured before parturition; this observation indicates that the shift in hepatic fatty acid composition is influenced by lipolysis. The increased lipolysis after parturition led to a vast increase in the hepatic triacyglycerol concentration and to a shift in hepatic fatty acid composition.