Fatty acid composition of the fats of the rumen and abomasum of sheep

The fatty acid composition of the abomasum and rumen tissues of 16-week old and 80-week old Romney ewes fed on pasture has been determined. For 16-week old lambs it was comparable to that of the longissimus dorsi of 26-week old lambs. At 80 weeks the rumen lipids showed a highly significant decrease in total saturated fatty acids, myristic acid and lower saturated acids with a corresponding increase in total unsaturated and octadecenoic (oleic) acids. The abomasum lipids showed similar changes. The reduced contents of myristic, lauric and decanoic acids in the lipids of the older animals were consistent with the removal of these acids from the diet. Whereas before weaning the dietary fetty acids are rich in myristic, lauric and decanoic acids, the fatty acids of sheep at pasture comprise mainly linotenic and palmitic acids. Consideration of the results of other investigations suggests that the changes in the fatty acid composition of the lipids of grazing sheep with age observed for the rumen and abomasum tissues may apply to muscle and fatty tissues generally.     

The fatty acid composition of the main phospholipid fractions of the rumen and abomasum tissues of foetal and adult sheep

The fatty acid composition has been determined on phosphatidyl choline, phos-phatidyl ethanolamine and sphingomyelin fractions earlier isolated from the rumen and abomasum tissues of foetal and of adult Romney sheep. The major proportion of polyunsaturated fatty acids was found in the phosphatidyl ethanolamine (17 to 43%) fraction and this was reduced in the phosphatidyl choline (7 to 25%) and sphingomyelin (1 to 4%) fractions. These features are in keeping with the results for mammalian tissues generally. The phosphatidyl ethanolamine fractions were further characterised by the low content of palmitic acid (<8%) compared with 25 to 30 % in the phosphatidyl choline fractions and 29 to 52% in the sphingomyelin fractions and by the occurrence of cyclopropane fatty acids. Consistent with the findings of other workers on mammalian tissues, the sphingomyelin fractions contained a relatively high content (16 to 27%) of higher w-saturated fatty acids including 22:0,23:0,24:0 and 25:0 and of tetracos-14-enoic (24:1 ω9) acid (5 to 16%). The total amounts of acids above C₂₀ tended to vary inversely with the levels of palmitic acid whereas the levels of stearic acid were relatively constant at 13 to 17%. Changes in fatty acid composition with age were generally not marked but the tissues of the foetus were distinguished from those of the foetus were distinguished from those of the adult by their substantial amount of eicosa-5,8,11-trienoic (20:3 ω9) acid together with relatively low contents of linoleic (18:2 ω6) and linolenic (18:3 ω3) acids and to a leser extent by reduced level of acids of the ω3 series. This was particularly reflected by the ratios of ω6/ω3 C₂₀ + C₂₂ acids in the phosphatidyl ethanolamine fractions, the valucs for the foetal rumen and abomasum tissues being 1.03 and 1.07, respectively, compared with corresponding values of 0.78 and 0.72 found in adult sheep. The results are consistent with a requirement for C₂₀ and C₂₂ polyunsaturated acids of the ω3 and ω6 series and some penetration of maternal fatty acids through the placenta. The resemblance between the fatty acid make-up and composition of foetal and maternal phospholipids suggests the possibiligy of transference of intact or lyso-phospholipids from the mother to the foetus through the placenta. However, such a possibility is counter-indicated by consideration of previous work using labelled intermediates and by the mechanism of conversion of linoleic and linolenic acids requiring their CoA derivatives in the formation of the corresponding polyunsaturated C₂₀ + C₂₂ acids. Nevertheless, the sharp cut-off of exogenous maternal fatty acids from the foetal triglycerides and their inclusion in the foetal phospholipids are not readily explainable.     

The composition and structure of the lipids of sheep lymph

Phosphatidylcholine was the principal phospholipid component in the intestinal lymph of sheep and was accompanied by small amounts of phosphatidylethanolamine, phosphatidylinositol, lysophosphatidylcholine and sphingomyelin. Stereo-specific analysis of the triacylglycerols confirmed that palmitic acid was concentrated in position sn-2 and showed that there was a higher proportion of the remaining saturated fatty acids in position sn-1 than in position sn-3. In the phosphatidylcholine, saturated fatty acids were concentrated in position sn-1 and unsaturated in position sn-2, contrary to an earlier report.     

Development of rumen function in calves: nature of protein reaching the abomasum

Effects of weaning age (4 and 8 wk) and ration (complete pelleted starter and unpelleted starter plus alfalfa-grass hay) on development of ruminal function were tested in a split-plot design. Maturity of ruminal function was estimated by the contribution of bacterial nitrogen to total nitrogen reaching the abomasum, essential amino acid composition of bacterial and abomasal protein, and ruminal volatile fatty acid concentrations. Sixteen Holstein bull calves were fitted with rumen and abomasal cannulas by 1 wk of age, and ingesta were sampled twice weekly from 2 to 11 wk of age. Contribution of bacterial nitrogen to total nitrogen in abomasal contents was similar to that of mature ruminants by 5 and 7 wk of age for calves weaned at 4 and 8 wk of age, respectively. Concentrations of ruminal volatile fatty acids indicative of mature ruminal function were reached by 5 wk of age. Pattern of essential amino acids in bacterial cells of the rumen was not affected by age, weaning age, or ration and was similar to that of mature ruminants. Analysis of abomasal digesta indicated no effect of starter ration and no effect of age or weaning age on the relative proportion of essential amino acids except lysine and arginine. Lysine decreased and arginine increased linearly from 2 wk until weaning.     

Changes in the rumen bacterial community in response to sunflower oil and fish oil supplements in the diet of dairy sheep

Rumen microbial biohydrogenation of dietary unsaturated fatty acids has a major effect on the process of developing healthier dairy products. This study aimed to investigate in vivo the effect of diet supplementation with sunflower (SO) and fish (FO) oils on the rumen bacterial community in dairy sheep. First, 32 lactating ewes, divided in 8 lots of 4 animals each (2 lots per treatment), were fed a high-concentrate total mixed ration supplemented with 0, 2% SO, 1% FO, or 2% SO plus 1% FO. After 21 d, rumen fluid samples were taken from each lot for DNA extraction and fluorescence in situ hybridization (FISH) analysis. In a second experiment, 5 cannulated ewes were first fed the same TMR, with the exception of a higher forage level, and then changed to the same diet supplemented with 2% SO plus 1% FO. After 0, 3, and 10 d, rumen content samples were taken for DNA extraction and FISH analysis (fluid). Total bacteria and the Butyrivibrio group were studied in microbial DNA by terminal RFLP analysis (T-RFLP), and real-time PCR was used to quantify Butyrivibrio bacteria that produce vaccenic acid or stearic acid. In rumen fluid samples, total bacteria and clostridial clusters IX and XIV were analyzed by FISH. Dietary supplementation with SO plus FO seemed to induce important changes in the total bacteria and Butyrivibrio populations, and a high interindividual variation was observed, and the speed of the effect of the lipid supplementation depended on the individual microbial composition. Analysis by T-RFLP and FISH showed increases in cluster IX bacteria with SO plus FO supplementation, presumably Quinella-like microorganisms. The abundances of vaccenic acid- and stearic acid-producing Butyrivibrio relative to total bacteria, estimated by real time PCR, were low (0.28 and 0.18%, respectively, in rumen fluid, and 0.86 and 0.81% in rumen contents) and only that of SA-producing bacteria seemed to be reduced by diets containing FO, although differences were only significant in lactating ewes. The T-RFLP analysis showed a variable effect of lipid supplementation on different bacteria of the family Lachnospiraceae, which includes the cultured bacteria known to be actively involved in rumen biohydrogenation. These results suggest that the latter bacteria do not play a dominant role in this process, and therefore other as-yet-uncultivated microorganisms might be more relevant.     

Genetic aspects of growth of Holstein-Friesian dairy cows from birth to maturity

In general, genetic selection is applied after first calving to traits that manifest themselves during the animal's productive life, mostly during the early part of productive life. This selection policy has had undesirable correlated responses in other economically important traits, such as health and fertility, and may also have had an effect on the growth of animals both during productive life and before first calving. In this study, we analyzed the growth trajectory of dairy heifers that had been selected for maximum production of combined fat and protein (measured in kg; select line) or for average production (control line) in the United Kingdom. Before first calving, these divergent lines were managed as a single group. Select line heifers grew faster than did control line heifers. They were also heavier at first calving, but by the end of 3 lactations, the lines were not significantly different in live weight. Selection primarily for yield and for other traits has led to heifers that grow faster and reach higher growth rates earlier in life. A genetic analysis of birth, weaning, and calving weights yielded heritability estimates of 0.53 (birth weight), 0.45 (weaning weight), and 0.75 (calving weight). Confidence intervals for the genetic correlations between the traits indicated that these BW traits are not under the same genetic control.     

Protein degradation in the rumen of sheep and cattle

Sheep and steers were given, at a maintenance level of feeding, four diets consisting of either poor quality dried grass, good quality dried grass or separate mixtures (63:35) of each of the dried grasses and barley. Ammonia and total N concentrations in rumen liquor were significantly higher in sheep than in steers whereas total volatile fatty acid concentration was significantly lower and protein N concentration, pH and rumen fluid dilution rate did not differ significantly between species. For all rumen measurements, except total volatile fatty acid concentration, there were significant differences between diets with the dietary responses being similar in both species. Protein degrading activity in the rumen was measured in vitro with casein as the substrate and in situ by measuring N disappearance when soyabean meal, cotton seed meal, groundnut meal, meat and bone meal, fish meal and dried grass were incubated in polyester bags in the rumen. Casein degrading activity of rumen liquor did not differ significantly between species, whereas rumen in-situ degradation of all feedstuffs, except fish meal, was significantly higher in sheep. In both species, ruminal casein degrading activity was higher when the good quality forage was given than when the poor quality forage was given and also increased when part of each forage was replaced by barley. In contrast, rumen in-situ degradability of feedstuffs did not differ when the two all-forage diets were given and the inclusion of barley in the diet reduced the rate of degradation. In both species and with all diets the rumen in-situ degradability ranking of the feedstuffs was similar.     

Changes in the composition of the fatty acids and aldehydes of meat lipids after heating

The effects of heating at 132°C on the fatty acids and fatty aldehydes of neutral lipids and phospholipids of lean beef, veal, lamb, pork and chicken were studied. Heating caused hydrolysis of the plasmalogens in the phospholipids, and varying amounts of the liberated fatty aldehydes were recovered in the neutral lipid fractions. Beef phosphatidyl choline lost more polyunsaturated fatty acids than that of the other meats. Beef and veal phosphatidyl ethanolamine lost more polyunsaturated fatty acid than that of lamb, pork or chicken, but the effect was obscured by the influx of fatty acids from elsewhere into this fraction after heating.     

Assessment of an in-situ technique to estimate the degradation of lipids in the rumen

In-situ disappearance of alfalfa hay, soybean, soybean meal and maize grain lipids and fatty acids were measured using two dairy cows. Bags were removed after 1, 2, 4 and 8 h incubation. Bacterial colonisation was estimated by labelling bacteria by a ¹⁵N infusion into the rumen. Results were then subtracted from calculations. Bacterial dry matter, lipids and fatty acids were highest for alfalfa hay and lowest for soybean. Disappearance of lipids and fatty acids was significantly higher for maize than for the other feeds. Stearic and octadecenoic acids appeared in hay and soybean as products of hydrogenation but no distinction could be made between fatty acids leaving the bags and fatty acids appearing or disappearing due to hydrogenation. Complete linolenic acid hydrogenation seems to be limited by the rate of hydrogenation of stearic acid into octadecenoic acids. Nylon bags seem to be a valuable tool to estimate hydrogenation or protection against hydrogenation in high linolenic content feeds.     

Changes of the composition in acerola (Malpighia emarginata DC.) fruit in relation to cultivar,growing region and maturity

BACKGROUND: Acerola (Malpighia emarginata DC.) has been known as a fruit rich in vitamin C. However, changes in composition of constituents in relation to cultivar, growing region and maturity have not been studied. We investigated the composition for five types of acerola fruits: three different cultivars (‘BOK’, ‘Flor Branca’ and ‘NRA309’) growing in Brazil, and one cultivar each in Vietnam (‘Vietnam’) and in Japan (‘Okinawa’). We also investigated the influence of fruit maturity on the compositional profiles. RESULTS: ‘BOK’ showed the highest vitamin C and malic acid contents whereas ‘Vietnam’ had the lowest vitamin C content. On the other hand, ‘NRA 309’ showed the highest level of total polyphenols. In the study of compositional changes during maturation, it was found that at immature stages proanthocyanidin was the major flavonoid, with high vitamin C content, but the levels of these constituents decreased as ripening progressed. At mature stages, anthocyanins appeared to be the major polyphenol in the ripe acerola fruit. CONCLUSION: This study showed that composition of acerola fruit differed significantly according to cultivar, growing region and maturity. The information provided in this study may help consumers to make an appropriate selection of functional food. Copyright © 2008 Society of Chemical Industry     

Changes in milk composition as affected by subclinical mastitis in sheep

The mechanism of the effects of glandular-level subclinical mastitis in dairy sheep on milk yield and on its composition as expressed in curd yield was studied. Thirty-six Israeli-Assaf dairy sheep with one udder half infected with identified coagulase-negative staphylococci and the contralateral gland free of bacteria were chosen. The milk yield of the infected halves was significantly lower than that of the uninfected ones (0.36 vs. 0.76 kg/milking). The somatic cell count and N-acetyl-beta-D-glucosaminidase activity were significantly higher in the infected halves than in the uninfected ones. The plasminogen activator and plasmin (PL) activities were significantly higher in the infected glands than in the uninfected ones, whereas plasminogen (PLG) activity and the ratio PLG:PL were significantly lower in the infected glands. Concentrations of Ca2+ did not differ, whereas Ca2+ activity was significantly lower and proteose peptone concentration was 2.4 times as high in the infected glands than in the uninfected ones. Curd yield was significantly lower in the infected glands than in the uninfected ones.     

Chemical composition of microbial matter in the rumen

Microbial fractions, comprising protozoa, large and small bacteria and whole particulate matter, have been isolated from rumen contents of sheep given a mainly concentrate diet, a mixture of hay and concentrate, and hay only. Samples of rumen contents were taken before and 2 h after feeding. The main components determined were: protein, lipid, nucleic acids, carbohydrate and ash. The amount of cell wall was estimated in terms of known cell wall constituents (diaminopimelic acid (DAP) and glucosamine). The concentration of some of the constituents varied with diet and with respect to the time of feeding. Many of the differences disappeared when the results were expressed on a polysaccharide-free basis. The amino acid composition of large and small bacteria was virtually the same. The amino acid composition of protozoa was similar except for the proportions of glutamic acid and lysine which were greater in protozoa, and alanine, glycine and DAP, the proportions of which were greater in bacteria. There were higher proportions of protein in large bacteria and protozoa than in small bacteria. Small bacteria contained more lipid, ash and DNA, and less RNA than the other two fractions. The polysaccharide content of protozoa and large bacteria increased from about 8% before feeding to about 30% after feeding, while the polysaccharide content of small bacteria increased only slightly after feeding.     

Dual X-ray absorptiometry accurately predicts carcass composition from live sheep and chemical composition of live and dead sheep

Fifty merino wethers (liveweight range from 44 to 81kg, average of 58.6kg) were lot fed for 42d and scanned through a dual X-ray absorptiometry (DXA) as both a live animal and whole carcass (carcass weight range from 15 to 32kg, average of 22.9kg) producing measures of total tissue, lean, fat and bone content. The carcasses were subsequently boned out into saleable cuts and the weights and yield of boned out muscle, fat and bone recorded. The relationship between chemical lean (protein+water) was highly correlated with DXA carcass lean (r(2)=0.90, RSD=0.674kg) and moderately with DXA live lean (r(2)=0.72, RSD=1.05kg). The relationship between the chemical fat was moderately correlated with DXA carcass fat (r(2)=0.86, RSD=0.42kg) and DXA live fat (r(2)=0.70, RSD=0.71kg). DXA carcass and live animal bone was not well correlated with chemical ash (both r(2)=0.38, RSD=0.3). DXA carcass lean was moderately well predicted from DXA live lean with the inclusion of bodyweight in the regression (r(2)=0.82, RSD=0.87kg). DXA carcass fat was well predicted from DXA live fat (r(2)=0.86, RSD=0.54kg). DXA carcass lean and DXA carcass fat with the inclusion of carcass weight in the regression significantly predicted boned out muscle (r(2)=0.97, RSD=0.32kg) and fat weight, respectively (r(2)=0.92, RSD=0.34kg). The use of DXA live lean and DXA live fat with the inclusion of bodyweight to predict boned out muscle (r(2)=0.83, RSD=0.75kg) and fat (r(2)=0.86, RSD=0.46kg) weight, respectively, was moderate. The use of DXA carcass and live lean and fat to predict boned out muscle and fat yield was not correlated as weight. The future for the DXA will exist in the determination of body composition in live animals and carcasses in research experiments but there is potential for the DXA to be used as an online carcass grading system.     

Repeatability of anogenital distance measurements from birth to maturity and at different physiological states in female Holstein cattle

The inverse association between anogenital distance (AGD; the distance from the center of the anus to the base of the clitoris) and fertility, its moderate heritability, and high variability reported in dairy cattle make AGD a promising candidate for further exploration as a reproductive phenotype. In addition to heritability, repeatability (i.e., consistency in measurements taken at different time points) is important for a reproductive phenotype to be considered useful in genetic selection. Therefore, our primary objective was to determine the repeatability of AGD from birth to breeding age (≈16 mo) in Holstein heifer calves, and during different stages of the estrous cycle, gestation, and lactation in Holstein cows. We also determined the associations among AGD, height (at the hip), and body weight (BW) at birth. In calves (n = 48), we recorded BW (kg) and height (cm) at birth and measured AGD (mm) at approximately 0, 2, 6, 9, 12, and 16 mo of age. In cows, AGD was measured at different stages of the estrous cycle (proestrus, estrus, metestrus and diestrus; n = 20), gestation (30, 90, 180, and 270 d; n = 78), and lactation (30–300 d in milk in 30-d increments; n = 30). Calf height and BW at birth had a weak positive association with AGD at birth. The AGD increased linearly from birth to breeding age, but there was no association between the AGD at birth and at breeding age in heifers. Although any 2 consecutive AGD measurements were correlated, 6 mo was the earliest age at which AGD was moderately correlated (r = 0.41) with that of breeding-age heifers. The AGD was neither influenced by the different stages of estrous cycle nor lactation and remained highly repeatable (r ≥ 0.95). Although AGD measurements at 30, 90, and 180 d of gestation (126.9, 126.7, and 127.7 mm, respectively) were strongly correlated (r ≥ 0.97) with each other, AGD at 270 d of gestation (142.8 mm) differed from AGD at all earlier stages of gestation. In summary, AGD measured at birth did not reflect AGD at breeding age in heifers, but AGD measurements in cows had high repeatability at all stages of the estrous cycle, gestation, and lactation, except at 270 d of gestation. Therefore, AGD could be measured reliably at any of the aforesaid physiological states in cows due to its high repeatability, except during late gestation. The earliest gestational stage when pregnancy-associated increase in AGD occurred, however, could not be definitively established in the present study.     

Nutrient demand interacts with legume maturity to affect rumen pool sizes in dairy cows

Effects of legume maturity on dry matter intake (DMI), milk production, ruminal fermentation and pool sizes, and digestion and passage kinetics, and the relationship of these effects with preliminary DMI (pDMI) were evaluated using 16 ruminally and duodenally cannulated Holstein cows in a crossover design with a 14-d preliminary period and two 17-d treatment periods. During the preliminary period, the pDMI of individual cows ranged from 22.9 to 30.0 kg/d (mean=25.9 kg/d) and the 3.5% fat-corrected milk yield ranged from 34.1 to 68.2 kg/d (mean=43.7 kg/d). Experimental treatments were diets containing alfalfa silage harvested either a) early-cut, less mature (EC) or b) late-cut, more mature (LC) as the sole forage. Early- and late-cut alfalfa contained 40.8 and 53.1% neutral detergent fiber (NDF) and 23.7 and 18.1% crude protein, respectively. Forage:concentrate ratios were 53:47 and 42:58 for EC and LC, respectively; both diets contained approximately 22% forage NDF and 27% total NDF. Preliminary DMI, an index of nutrient demand, was determined during the last 4d of the preliminary period when cows were fed a common diet and used as a covariate. Main effects of alfalfa maturity and their interaction with pDMI were tested by ANOVA. Alfalfa maturity and its interaction with pDMI did not affect milk yield but EC increased DMI compared with LC; thus, EC had lower efficiency of milk production than LC. The EC diet decreased milk fat concentration more per kilogram of pDMI increase than the LC diet, but milk fat yield was not affected. The lower concentration and faster passage rate of indigestible NDF for EC resulted in lower rumen pools of indigestible NDF, total NDF, and dry matter than did LC, which EC increased at a slower rate than did LC as pDMI increased. The EC diet decreased starch intake and increased ruminal pH compared with the LC diet. The rate of ruminal starch digestion was related to level of intake, but this did not affect ruminal or postruminal starch digestion. Total-tract digestibility of NDF, organic matter, and dry matter was higher for EC than LC. Microbial efficiency tended to be related to pDMI and the response differed by treatment. When alfalfa silage was the only source of forage in the diet, cows supplemented with additional concentrate to account for decreased protein and increased fiber concentrations associated with LC produced similar fat-corrected milk yields with greater efficiency than cows fed EC.     

Changes in terpenoid composition of milk and cheese from commercial sheep flocks associated with seasonal feeding regimens throughout lactation

Changes in the terpenoid content of milk and cheese from commercial sheep flocks monitored throughout lactation in the Cantabrian area of northern Spain were investigated. The flocks followed the same seasonal feeding strategy during lactation: indoor feeding in winter (early lactation) based on concentrate and forage; part-time grazing in the valley in early spring (mid lactation); and from mid spring on (late lactation), flocks were managed under extensive mountain grazing. In the present study design, seasonal feeding and lactation stage were intrinsically linked and could not be considered in isolation, and a holistic approach was necessary to consider the whole production management of the commercial flocks studied. Furthermore, the study focused on the identification of sesquiterpenoid ratios to differentiate milks and cheeses produced under extensive mountain grazing from those produced under other seasonal feeding regimens. Total abundance of mono- and sesquiterpenoids and that of individual compounds such as α-pinene, β-caryophyllene, α-humulene, α-amorphene, and γ-cadinene significantly increased in milk and cheese from indoor feeding to mountain extensive grazing. Sesquiterpenoid ratios such as γ-cadinene/α-muurolene, γ-cadinene/δ-cadinene, β-caryophyllene/α-muurolene, and (β-caryophyllene + γ-cadinene)/α-muurolene were used to differentiate mountain milks and cheeses from those from indoor feeding and part-time grazing in the valley. Multivariate discriminant analysis applied to individual terpenoids and sesquiterpenoid ratios showed milk and cheese samples classified into 2 groups: samples from indoor feeding and part-time grazing in the valley were classified together, and clearly separated from mountain milks and cheeses. The results of the present study showed that the sesquiterpenoid ratios approach could help to differentiate mountain dairy products from others obtained under other specific feeding regimens in a local environment.     

The composition of lipids from rice hulls and from the surface of rice caryopsis

Samples of hulls, of whole and ground caryopsis and of bran obtained from the Brazilian rice variety IAC 1246, were extracted with hexane and the characteristics and composition of the corresponding lipids were determined. The lipids from rice hulls showed a four times higher content of unsaponifiable matter and of free fatty acids than those from rice bran and rice caryopsis. There were also differences in the fatty acid composition as evidenced by the presence of 2–3% of saturated C₂₂ and C₂₄ acids and a lower proportion of unsaturated acids in the rice hull lipids. On the other hand there was a close resemblance between the rice hull lipids and those on the surface of the caryopsis. Chromatographic analysis of the unsaponifiable matter of lipids from rice hulls and caryopsis surface disclosed the presence of hydrocarbons, alcohols and sterols in ascending order, the sterols consisting of about 50% of β-sitosterol, 20–40% of campesterol, 10–20% of stigmasterol and 2–3% of cholesterol. On the basis of the above results it was concluded that a preliminary solvent extraction of paddy rice in order to remove the waxy lipids from the hulls and the caryopsis surface would benefit the subsequent milling process and improve the quality of the brown rice and of crude rice bran oil.