Effect of a supplement rich in linolenic acid added to the diet of post partum dairy cows on ovarian follicle growth, and milk and plasma fatty acid compositions

The objective of this study was to determine the effect of a linseed supplement on follicle growth, progesterone concentrations and milk and plasma fatty acids in dairy cows post partum. Sixteen Holstein cows were given a basal total mixed diet plus one of two supplements: control (C; extruded soybeans; n = 8) or linseed (L; extruded linseeds; n = 8). One month after calving oestrous cycles were synchronised (PRID). Follicle growth and milk progesterone concentrations were measured every 2 d over the induced oestrous cycle. Milk production characteristics were unaffected by treatment. The L cows lost significantly more BCS than the C cows (P < 0.01). Plasma insulin, glucose and urea were unaffected by the treatment. Plasma NEFA tended to be affected by the treatment (L > C, P = 0.08). The proportions of 18:3n-3 in milk and plasma were increased by L compared to C (P < 0.001 and P < 0.01, respectively). There was an effect of dietary supplement on the numbers of small follicles (L < C, P < 0.05). Milk progesterone was unaffected by treatment. In conclusion, the increased supply of 18:3n-3 to the cows had only a modest effect on follicle populations and corpus luteum activity was unchanged.     

Effect of supplementation with different fat sources on the mechanisms involved in reproductive performance in lactating dairy cattle

Supplementary fat positively influences reproductive performance in dairy cattle, although the mechanisms involved are not clearly defined. Our objective was to determine the effects of four different fat supplements on follicle development, plasma steroid hormone concentrations and prostaglandin (PG) synthesis in lactating dairy cattle. Forty-eight early lactation Holstein-Friesian cows (21 primiparous, 27 multiparous) were used in a completely randomized block design. Cows were fed the same basal TMR diet and received one of four fat supplements: (i) palmitic acid (18:0 fatty acid; Control), (ii) flaxseed (rich in 18:3 n-3 fatty acid; Flax), (iii) conjugated linoleic acid (a mixture of cis-9, trans-11 and trans-10, cis-12 isomers; CLA), and (iv) fish oil (rich in 20:5 and 22:6 n-3 fatty acids; FO). All lipid supplements were formulated to be isolipidic; palmitic acid was added as necessary to provide a total lipid supplement intake of 500 g/day. Cows were synchronized to be in estrus on Day 15 of dietary treatment. All antral follicles were counted, and dominant follicles, subordinate follicles and corpora lutea were measured daily via transrectal ovarian ultrasonography for one complete estrous cycle. Blood samples were collected daily, and selected samples were analyzed for progesterone, estradiol, insulin-like growth factor-1, insulin, cholesterol and non-esterified fatty acids. Estrus was synchronized a second time, and liver and endometrial biopsies were collected on Day 7 of the estrous cycle. Gene expression was evaluated for a number of genes involved in prostaglandin synthesis (endometrium) and fatty acid uptake and utilization (liver). Fat supplementation had little effect on follicle development. Cows receiving supplementary n-3 fatty acids had lesser plasma progesterone (P4) and smaller corpora lutea than cows receiving the CLA or Control supplements. Effects of fat supplementation on the endometrial expression of genes involved in PG synthesis were minor. Hepatic expression of SREBF1, ASCL1 and FABP1 was reduced by FO supplementation. Reduced plasma P4 in n-3 supplemented cows may lead to a suboptimal uterine environment for embryo development and hence reduced fertility compared to cows receiving the control or CLA supplements.     

Influence of pumpkin seed cake and extruded linseed on milk production and milk fatty acid profile in Alpine goats

The aim was to determine the effect of substituting pumpkin seed cake (PSC) or extruded linseed (ELS) for soya bean meal in goats’ diets on milk yield, milk composition and fatty acids profile of milk fat. In total, 28 dairy goats were divided into three groups. They were fed with concentrate mixtures containing soya bean meal (Control; n=9), ELS (n=10) or PSC (n=9) as main protein sources in the trial lasting 75 days. Addition of ELS or PSC did not influence milk yield and milk gross composition in contrast to fatty acid profile compared with Control. Supplementation of ELS resulted in greater branched-chain fatty acids (BCFA) and total n-3 fatty acids compared with Control and PSC (P<0.05). Total n-3 fatty acids were accompanied by increased α-linolenic acid (ALA, C18:3n-3; 0.56 g/100 g fatty acids) and EPA (C20:5n-3; 0.12 g/100 g fatty acids) proportions in milk of the ELS group. In contrast, ELS and PSC resulted in lower linoleic acid (LA, C18:2n-6; 2.10 and 2.28 g/100 g fatty acids, respectively) proportions compared with Control (2.80 g/100 g fatty acids; P<0.05). Abovementioned resulted in lower LA/ALA ratio (3.81 v. 7.44 or 6.92, respectively; P<0.05) with supplementation of ELS compared with Control or PSC. The PSC diet decreased total n-6 fatty acids compared with the Control (2.96 v. 3.54 g/100 g fatty acids, P<0.05). Oleic acid (c9-C18:1), CLA (c9,t11-18:2) and t10-,t11-C18:1 did not differ between treatments (P⩾0.08), although stearic acid (C18:0) increased in ELS diets compared with Control (12.7 v. 10.2 g/100 g fatty acids, P<0.05). Partially substituted soya bean meal with ELS in hay-based diets may increase beneficial n-3 fatty acids and BCFA accompanied by lowering LA/ALA ratio and increased C18:0. Pumpkin seed cake completely substituted soya bean meal in the diet of dairy goats without any decrease in milk production or sharp changes in fatty acid profile that may have a commercial or a human health relevancy.     

Polyunsaturated fatty acids and choline in dairy goats nutrition: Production and health benefits

The potential to modify milk fatty acid composition and milk production by dietary administration of marine oils rich in n-3 PUFAs in goats diets is reviewed. Moreover animal and human health implications are considered. Role of nutrition in dairy goats for enhancing content of CLA in milk fat is also discussed. At last, rumen protected choline supplementation is evaluated to improve productive performance and metabolic health. While the effects of n-3 PUFAs administration on goat productive performance seem to depend on many factors, fish oil administration has been extensively shown to lower average concentration of C18:0 and saturated fatty acids, with a relative increase of C16:1, C18:3 n-3 and very long-chain n-3 PUFAs. Positive results have been evidenced in animals health following administration of EPA and DHA from fish oil, leading to increased phagocytic activity with no effects on extracellular ROS production in incubated goats cells. The nutritional and health properties of goat's milk could be further improved by increasing the content of CLA in milk fat. Provision of PUFAs from fresh pasture and plant lipids, mainly C18:2 n-6 and C18-3 n3 which serve as precursor for trans C18:1 formation in the rumen, have proved to enhance content of CLA in goat milk fat. Marine oils rich in n-3 PUFAs have been shown to be very effective at increasing CLA content in bovine milk, but very scarce data are available on dairy goats.Rumen protected choline has been show to increase productive performance, particularly milk production, fat percentage, and fat and protein yield without detrimental effects on methyl groups, thus reducing BHBA plasma content and hepatocellular lipid accumulation around transition.However the magnitude of the production response seems to be affected by the composition of the diet, and other factors as already reported for n-3 PUFAs administration.     

Effects of starch-rich or lipid-supplemented diets that induce milk fat depression on rumen biohydrogenation of fatty acids and methanogenesis in lactating dairy cows

Optimizing milk production efficiency implies diets allowing low methane (CH₄) emissions and high dairy performance. We hypothesize that nature of energy (starch v. lipids) and lipid supplement types (monounsaturated fatty acid (MUFA) v. polyunsaturated fatty acid (PUFA) mitigate CH₄ emissions and can induce low milk fat content via different pathways. The main objective of this experiment was to study the effects of starch-rich or lipid-supplemented diets that induce milk fat depression (MFD) on rumen biohydrogenation (RBH) of unsaturated fatty acids (FA) and enteric CH₄ emissions in dairy cows. Four multiparous lactating Holstein cows (days in milk=61±11 days) were used in a 4×4 Latin square design with four periods of 28 days. Four dietary treatments, three of which are likely to induce MFD, were based (dry matter basis) on 56% maize silage, 4% hay and 40% concentrates rich in: (1) saturated fatty acid (SFA) from Ca salts of palm oil (PALM); (2) starch from maize grain and wheat (MFD-Starch); (3) MUFA (cis-9 C18:1) from extruded rapeseeds (MFD-RS); and (4) PUFA (C18:2n-6) from extruded sunflower seeds (MFD-SF). Intake and milk production were measured daily. Milk composition and FA profile, CH₄ emissions and total-tract digestibility were measured simultaneously when animals were in open-circuit respiration chambers. Fermentation parameters were analysed from rumen fluid samples taken before feeding. Dry matter intake, milk production, fat and protein contents, and CH₄ emissions were similar among the four diets. We observed a higher milk SFA concentration with PALM and MFD-Starch, and lower milk MUFA and trans-10 C18:1 concentrations in comparison to MFD-RS and MFD-SF diets, while trans-11 C18:1 remained unchanged among diets. Milk total trans FA concentration was greater for MFD-SF than for PALM and MFD-Starch, with the value for MFD-RS being intermediate. Milk C18:3n-3 content was higher for MFD-RS than MFD-SF. The MFD seems more severe with MFD-SF and MFD-RS than PALM and MFD-Starch diets, because of a decrease in milk SFA concentration and a stronger shift from trans-11 C18:1 to trans-10 C18:1 in milk. The MFD-SF diet increased milk trans FA (+60%), trans-10 C18:1 (+31%), trans-10,cis-12 CLA (+27%) and PUFA (+36%) concentrations more than MFD-RS, which explains the numerically lowest milk fat yield and indicates that RBH pathways of PUFA differ between these two diets. Maize silage-based diets rich in starch or different unsaturated FA induced MFD with changes in milk FA profiles, but did not modify CH₄ emissions.     

Effect of extruded linseeds alone or in combination with fish oil on intake,milk production,plasma metabolite concentrations and milk fatty acid composition in lactating goats

Based on the potential benefits for long-term human health, there is interest in developing sustainable nutritional strategies for lowering medium-chain saturated fatty acids (FA) and increasing specific unsaturated FA in ruminant milk. Dietary supplements of extruded linseeds (EL), fish oil (FO) or a mixture of EL and FO increase cis-9,trans-11 CLA and long-chain n-3 polyunsaturated FA in bovine milk. Supplements of FO cause milk fat depression in lactating cows, but information for dairy goats is limited. A total of 14 Alpine goats were used in a replicated 3×3 Latin square with 28-days experimental periods to examine the effects of EL alone or in combination with FO on animal performance, milk fat synthesis and milk FA composition. Treatments comprised diets based on natural grassland hay supplemented with no additional oil (control), 530 of EL or 340 g/day of EL and 39 g/day of FO (ELFO). Compared with the control, ELFO tended (P=0.08) to lower milk fat yield, whereas EL increased (P<0.01) milk fat content and yield (15% and 10%, respectively). Relative to EL, ELFO decreased (P<0.01) milk fat content and yield (19% and 17%, respectively). Relative to the control and ELFO, EL decreased (P<0.05) milk 10:0 to 16:0 and odd- and branched-chain FA content and increased 18:0, cis-18:1, trans-13 18:1 (and their corresponding ∆-9 (desaturase products), trans-12,cis-14 CLA, cis-13,trans-15 CLA, cis-12,trans-14 CLA and trans-11,cis-13 CLA and 18:3n-3 concentrations. ELFO was more effective for enriching (P<0.05) milk cis-9, trans-11 CLA and trans-11 18:1 concentrations (up to 5.4- and 7.1-fold compared with the control) than EL (up to 1.7- and 2.5-fold increases). Furthermore, ELFO resulted in a substantial increase in milk trans-10 18:1 concentration (5.4% total FA), with considerable variation between individual animals. Relative to the control and EL, milk fat responses to ELFO were characterized by increases (P<0.05) in milk trans-16:1 (Δ9 to 11), trans-18:1 (Δ6 to 11), trans-18:2, CLA (cis-9,trans-11, trans-9,cis-11, trans-8,trans-10 and trans-7,trans-9) and 20- and 22-carbon FA concentrations. Overall, EL resulted in a relatively high cis-9 18:1 concentration and an increase in the 18:3n-3/18:2n-6 ratio, whereas combining EL and FO resulted in substantial increases in trans-FA, marginal enrichment in 20:5n-3 and 22:6n-3 and lower 16:0 concentration changes associated with a decrease in milk fat content. In conclusion, data provide further evidence of differential mammary lipogenic responses to diet in the goat compared with the cow and sheep.     

High- and low-purity glycerine supplementation to dairy cows in early lactation: effects on silage intake,milk production and metabolism

This study evaluated the effects of supplemental low- and high-purity glycerine on silage intake, milk yield and composition, plasma metabolites and body condition score (BCS) in dairy cows. A total of 42 cows of the Swedish Red Breed, housed in individual tie stalls, were fed 0.25 kg of low- or high-purity glycerine on top of concentrate, twice daily, during the first 4 weeks of lactation. One-third of the cows acted as controls, receiving no glycerine. Silage was fed for ad libitum intake and concentrate was fed at restricted level of intake, about 6 kg/day for primiparous cows and 7 kg/day for multiparous cows. Feed refusals were weighed daily. Cows were milked twice daily, milk yield was recorded on four occasions per week and milk samples were collected simultaneously. Blood samples were drawn from the coccygeal vessel once a week. Low- and high-purity glycerine had no effect on silage or total dry matter intake (P = 0.38 and P = 0.75, respectively) or on BCS (P = 0.45). Cows fed high-purity glycerine tended to have higher milk yield than control cows (P = 0.06). Milk composition tended to differ among treatments. No main effects of treatment on concentration of glycerine (P = 0.44), glucose (P = 0.78), insulin (P = 0.33), non-esterified fatty acids (P = 0.33) and β-hydroxybutyrate (P = 0.15) in plasma. These data indicate that high-purity glycerine has the potential to increase milk yield, as well as enhance the milk protein concentration and milk fat + protein yield.     

Effects of short-term oilseed supplementation on plasma fatty acid composition,progesterone and prostaglandin F metabolite in lactating beef cows

Twenty-four 3-year-old Angus cows (512.2±21.6 kg) and six ruminally cannulated beef heifers (523.1±16.9 kg) were used to determine the impact of feeding oilseeds starting at the beginning of estrous synchronization until maternal recognition of pregnancy on plasma fatty acid composition. Starting ~60 days postpartum cows were synchronized with the Select Synch+controlled internal drug-release (CIDR) device and timed artificial insemination (AI) protocol. The day CIDR was inserted; cattle were randomly assigned to one of the three treatments being grazing only (CON) or a supplement containing whole soybeans (SOY); or whole flaxseed (FLX). Cattle continued to receive these diets for 28 days. Blood was collected every 3 days until 10 days after insemination and then every day until 18 days after insemination. All cattle grazed a common pasture and supplemented cattle were individually fed their respective supplements once daily. Ruminally cannulated heifers were used to evaluate the impact supplements had on forage intake, which was reduced (P=0.05) with oilseed supplementation. Feeding oilseeds increased total fatty acid intake (P<0.001) across treatments with SOY having greater (P<0.001) 18:2n-6 intake than either CON or FLX. Likewise, cattle fed FLX had greater (P<0.001) 18:3n-3 intake than either CON or SOY. There was a treatment×time interaction (P⩽0.05) for all fatty acids identified except for 20:5n-3 (P=0.99). Within 3 days after the start of supplementation, plasma concentrations of 18:2n-6 increased (P<0.001) for cattle fed SOY compared with CON or FLX, whereas flax-fed cattle did not exhibit an increase (P=0.02) until day 15 of supplementation over that of CON. Plasma concentrations for 18:3n-3 was greater (P<0.013) for FLX than both CON and SOY by day 12. Feeding flaxseed tended to (P=0.07) increase and increased (P=0.01) plasma concentrations of 20:4n-6 by day 18 over CON and SOY, respectively. Overall, treatment did not affect serum concentration of progesterone (P=0.18) or prostaglandin F metabolite (P=0.89). However, day after breeding had an effect on serum progesterone (P=0.01) with day 16 after timed AI being lower compared with other days. Feeding oilseeds during the time of estrous synchronization will not only increase the energy density of the diet but will provide key fatty acids around the time of maternal recognition of pregnancy.     

Effects of olive and fish oil Ca soaps in ewe diets on milk fat and muscle and subcutaneous tissue fatty-acid profiles of suckling lambs

Enhancing healthy fatty acids (FAs) in ewe milk fat and suckling lamb tissues is an important objective in terms of improving the nutritional value of these foods for the consumer. The present study examined the effects of feeding-protected lipid supplements rich in unsaturated FAs on the lipid composition of ewe milk, and subsequently in the muscle and subcutaneous adipose tissues of lambs suckling such milk. Thirty-six pregnant Churra ewes with their new-born lambs were assigned to one of three experimental diets (forage/concentrate ratio 50 : 50), each supplemented with either 3% Ca soap FAs of palm (Control), olive (OLI) or fish (FO) oil. The lambs were nourished exclusively by suckling for the whole experimental period. When the lambs reached 11 kg BW, they were slaughtered and samples were taken from the Longissimus dorsi and subcutaneous fat depots. Although milk production was not affected by lipid supplementation, the FO diet decreased fat content (P<0.001), whereas the OLI milk FA profile resembled that of the Control diet. In contrast, although FO drastically diminished the contents of stearic and oleic acids (P<0.001), all the saturated even-numbered carbon FAs from 6:0 to 14:0 increased (P<0.05). FO also produced the highest levels of c9,t11-18:2 (2.21%) and n-3 FAs, 20:5 n-3 (0.58%), 22:5 n-3 (0.48%) and 22:6 n-3 (0.40%). The high levels of trans-11 18:1 (7.10%) obtained from the FO diet would suggest that Ca soaps only confer partial protection in the rumen. In contrast, the lack of significant differences in trans-10 18:1 levels (P>0.05) and other trans-FAs between Control and FO treatments would indicate that FO treatment does not alter rumen biohydrogenation pathways under the assayed conditions. Changes in dam milk FA composition induced differences in the FA profiles of meat and fat depots of lambs, preferentially incorporated polyunsaturated FAs into the muscle rather than storing them in the adipose tissue. In the intramuscular fat of the FO treatment, all the n-3 FAs reached their highest concentrations: 0.97 (18:3 n-3), 2.72 (20:5 n-3), 2.21 (22:5 n-3) and 1.53% (22:6 n-3). In addition, not only did FO intramuscular fat have the most cis-9, trans-11 18:2 (1.66%) and trans-11 18:1 (3.75%), but also the lowest n-6/n-3 ratio (1.80) and saturated FA content were not affected. Therefore, FO exhibited the best FA profile from a nutritional point of view.     

Plasma,milk and faecal progesterone concentrations during the oestrous cycle of lactating dairy cows with different milk yields

The hypotheses tested in this study were that neither average progesterone (P4) concentrations in plasma and milk nor average progesterone metabolites concentrations in faeces would differ during an oestrous cycle in two groups of cows with differing daily milk yields. High producing (HP = 8) and low producing (LP = 8) dairy cows were selected randomly for the study. Their oestrous cycles were initially synchronised using P4 and prostaglandin F2alpha. Chromic oxide capsules were administered twice daily to measure total faecal output. Samples of blood, faeces and milk were taken daily throughout one oestrous cycle, plasma and milk P4, and faecal progesterone metabolites (FP4M) assayed. The average daily milk yields in the two groups were 30.8 and 21.9l per day, respectively (P < 0.0001), although daily faecal output was similar in both the groups (HP, 7.7 versus LP, 6.9 kg DM; P = 0.24). Mean plasma and milk P4 concentrations were similar in both the groups (plasma P4, 4.12 versus 4.05 ng/ml; P = 0.3; milk P4, 8.2 versus 8.3; P = 0.9) during dioestrus. Average daily excretion of P4 to the milk was greater in HP than LP cows (252 versus 185 microg, P = 0.04). Neither concentration nor the daily yield of FP4Ms was affected by level of milk yield (concentration: 12.2 versus 11.5 microg/g; daily yield: 89.1 versus 82.9 mg per day; P > 0.05). These data showed that the concentrations of P4 in plasma and milk, and the concentrations and daily yields of FP4M were not affected by the level of daily milk yields which differed by about 41% of the LP average of 21.9l.     

Plasma oestradiol and progesterone during early pregnancy in the cow and the effects of treatment with buserelin

We have monitored plasma concentrations of oestradiol and progesterone after insemination in dairy cows, and investigated the effects of injection with 10 μg of the gonadotrophin-releasing hormone (GnRH) analogue buserelin, a treatment known to result in an improvement in conception rate. Animals were injected intramuscularly on Day 12 after insemination with 2.5 ml of either control saline (n = 29) or buserelin (n = 26). Blood samples were collected from Day 8 to Day 17 and milk samples from the day of insemination until Day 30. On the basis of milk progesterone profiles, in the control group 15 cows remained pregnant (control pregnant) and 11 underwent luteolysis (control not pregnant), whereas in the treated group 13 cows remained pregnant (treated pregnant) and 13 underwent luteolysis (treated not pregnant). Three cows were excluded from the control group owing to high progesterone at insemination or failed ovulation. In both the control and treated groups mean plasma progesterone concentration was significantly (P < 0.05) lower in non-pregnant cows than in pregnant ones from Day 12 post-insemination. However, no significant effect of buserelin treatment on plasma progesterone concentration was detected. In the control group the plasma oestradiol concentration was similar in the pregnant and non-pregnant cows. In the treated group, plasma oestradiol concentration in the non-pregnant cows was similar to that in the control group, whereas in the treated pregnant cows the plasma oestradiol concentration showed a significant (P < 0.05) decline after treatment. As oestradiol is known to stimulate the development of the luteolytic mechanism at this time, we suggest that buserelin is acting to reduce the strength of the luteolytic drive in some cows, thus improving the chance of the embryo being able to prevent luteolysis.     

The effect of N-fertilisation rate or inclusion of red clover to timothy leys on fatty acid composition in milk of dairy cows fed a commercial silage : concentrate ratio

The aim of this experiment was to, under typical Swedish production conditions, evaluate the effects of grass silages subjected to different N-fertilisation regimes fed to dairy cows on the fatty acid (FA) composition of their milk, and to compare the grass silages in this respect to red clover-dominated silage. Grass silages made from first year Phleum pratense L. leys subjected to three N-fertilisation regimes (30, 90 and 120 kg N/ha, designated G-30, G-90 and G-120, respectively) and a mixed red clover–grass silage (Trifolium pratense L. and P. pratense L.; 60/40 on dry matter (DM) basis, designated RC–G) were produced. The experiment was conducted as a change-over design, including 24 primiparous and multiparous dairy cows of the Swedish Red breed, each of which was allocated to three of the four diets. The cows were offered 11 kg DM of silage and 7 kg concentrates. The silages had similar DM and energy concentrations. The CP concentration increased with increase in N-fertilisation level. There was a linear increase in DM intake of the different silages with increased N fertilisation. There were also differences in concentrations of both individual and total FAs amongst silages. The daily milk production (kg/day) did not significantly differ between treatments, but G-30 silage resulted in higher concentrations of 18:2n-6 in the milk compared with the other two grass silages. The highest concentrations of 18:3n-3 and cis-9, trans-11 18:2 were found in milk from cows offered the RC–G silage. The G-30 diet resulted in higher concentration of 18:2n-6 and the same concentration of 18:3n-3 in the milk as the other grass silages, despite lower intake levels of these FAs. The apparent recoveries of 18:3n-3 from feed to milk were 5.74%, 4.27%, 4.10% and 5.31% for G-30, G-90, G-120 and RC–G, respectively. A higher recovery when red clover is included in the diet confirms previous reports. The higher apparent recovery of 18:3n-3 on the G-30 treatment may be related to the lower silage DM intake, which led to a higher relative proportion of ingested FAs originating from concentrates compared with the G-90 and G-120 diets. With the rates and types of concentrates used in this study, the achieved differences in FA composition among the silages were not enough to influence the concentrations of unsaturated FAs in milk.     

Postpartal ovarian activity of healthy cows and those affected by subclinical metabolic disorders

The postpartal ovarian activity was studied in healthy cows and in those affected by subclinical fatty liver disease and subclinical primary ketosis. Twenty-six dairy cows, 4–7 years old, with not less than 5000 l milk yield in the preceding lactation, were monitored for the following blood parameters: aspartate-amino-transferase (AST)/glutamicoxalacetic transaminase (GOT), albumin, total protein, total lipid, cholesterol, non-esterified fatty acid (NEFA) and triglyceride levels, glucose and ketones. The ratios albumin : total protein and NEFA : triglyceride were also calculated. Blood samples were collected once a week between days 255 and 260 of gestation and days 1–15 postpartum, and subsequently on the 30th, 45th and 60th days postpartum. Based on the biochemical parameters, the cows were assigned in retrospect to three groups: (1) healthy (n = 5), (2) subclinical fatty liver disease (n = 6), and (3) subclinical primary ketosis (n = 10). The postpartal ovarian activity was assessed by rectal palpation and by milk progesterone levels, determined by radioimmunoassay in samples collected 2–3 times weekly between days 5 and 70 postpartum.As early as 10–18 days postpartum, ovarian activity was evident in healthy cows. This was confirmed by the progesterone profiles indicating three regular ovarian cycles with normal hormone levels within 70 days postpartum. All five healthy cows were detected in estrus and only one failed to conceive after insemination.The six cows with subclinical fatty liver disease had no regular cycles and only a few small follicles were palpable on their ovaries. The milk progesterone fluctuated around the basal level (? 1.6 nmol/l). The first Graafian follicles appeared as late as days 30–35 postpartum and the luteal function commenced only between days 38 and 60, as indicated by palpation of corpora lutea and a concomitant rise in milk progesterone. The progesterone peaks were at the lower physiological limits characteristic of luteal function.The ovarian activity of the ten cows with subclinical primary ketosis was intermediate between that of healthy and fatty liver cows. The first follicles and corpora lutea were somewhat delayed, and the progesterone levels fluctuated considerably during the luteal phase. One cow in this group resumed ovarian inactivity during the 70-day postpartal observation period.     

Immune and oxidative response to linseed in the diet of periparturient Holstein cows

The aim of this research was to determine the influence of dietary replacement of n-6 with n-3 polyunsaturated fatty acids on cellular immunity and oxidative stress in the transition period dairy cows. The experiment was conducted on 20 dairy Holstein cows from 3±1 weeks before parturition until the 6^th week of lactation. Both groups were fed an iso-energetic and iso-nitrogenous diet. Soybean meal from control (C) group was replaced with linseed in the experimental (LS) group. Cellular immunity and oxidative stress were measured on days −10, 1, 21 and 42 relative to parturition. During the entire experimental period, the proportion of CD45⁺ cells was lower (P<0.05) in LS group compared with the C group. The phagocytosis ability and phagocytosis index of cows fed with n-3 fatty acids were significantly reduced (P<0.05) compared with the group of cows fed with n-6 fatty acids. The most severe decrease in phagocytosis ability was on day −10 and 1 relative to parturition. The activity of superoxide dismutase (P<0.05) and plasma glutathione peroxidase (P<0.05) increased around calving, although activities were not influenced by dietary treatment. Increased malondialdehyde concentration (P<0.05) was influenced by dietary n-3 fatty acids and the time relative to parturition. The immune suppression was most pronounced during periparturient period. In that matter we can conclude that not only dietary n-3 fatty acids but also oxidative stress, which reached peak at time of parturition, contributed to the reduced cellular immunity during the periparturient period.     

Prenatal and postnatal transfer of fatty acids from mother to pup in the hooded seal

Unlike most mammals, hooded seal (Cystophora cristata) pups are born with a substantial layer of adipose tissue. Subsequently, during the brief lactation period of only 4 days, fasting mothers mobilize enormous amounts of lipid from blubber and secrete milk (60% fat) at rates of 10 kg·day^-1. Pups gain 7 kg·day^-1 due primarily to the deposition of fat in blubber. We measured blubber content and fatty acid composition of blubber and milk in hooded seal mother-pup pairs at birth and over the 4-day lactation period to examine the nature and source of fetal lipids, the incorporation of maternal blubber fatty acids into milk lipid, and patterns of fatty acid deposition in suckling young. The fatty acid composition of the blubber of the newborn was notably different from that of its mother. Fetal deposition was likely due to a combination of both fetal synthesis and direct placental transfer of maternal circulating fatty acids. The blubber of the newborn was characterized by high levels (>90% of total fatty acids) of saturated and monounsaturated fatty acids of primarily endogenous origin. In particular, the fetus appeared to have high Δ-9 desaturase activity as evidenced by the large amounts of 14:1n-5 (4.2%) and 16:1n-7 (37.0%) in newborn blubber compared to maternal blubber (0.2% and 14.1%, respectively). Nevertheless, essential and long-chain polyunsaturated fatty acids of the n-3 and n-6 families, which could only have originated by direct transfer from the mother, comprised>7% of pup blubber fatty acids and indicated greater rates of placental transfer than found in humans. In hooded seal mothers, rapid lipid transfer during the brief lactation period appeared to be facilitated by direct incorporation of mobilized fatty acids into milk. Although some differences in proportions of specific fatty acids were found between milk and maternal blubber, most of these differences declined over the course of lactation. However, selective mobilization of 20:5n-3 from maternal blubber into milk was apparent throughout lactation and resulted in elevated levels in pup blubber at weaning compared to maternal blubber. Ingested fatty acids were deposited directly and without modification into the blubber of pups, and by 4 days the fatty acid composition of pup blubber was virtually identical to that of the milk consumed.     

Use of fluorogestone acetate after breeding to reduce the effect of premature luteal regression in dairy goats when superovulation is induced with FSH

The aim of the present study was to determine the effect of fluorogestone acetate (FGA) administered after mating, on embryo production in the dairy goat subjected to conventional superovulatory and embryo recovery protocols. Adult does, most of them of the French Alpine breed, were randomly assigned after a FSH-superovulatory estrus and fertile matings to a control group (n=20) or to a treated group (n=20) in which intravaginal sponges impregnated with FGA were inserted after mating and remove before embryo collection (day 6). Blood samples were collected every 12h from days 1 to 7 post-estrus and serum progesterone concentrations were determined. The FGA-group had a lesser percentage of does with normal corpora lutea (CL) and a greater percentage of animals with CL in regression or mixed (normal and in regression) when compared with the control group (13.3 and 64.7%, 53.3 and 23.5%, and 33.3 and 11.8%, respectively; P<0.05). Mean number of normal CL per doe was less and mean number of regressed CL greater in FGA as compared with the control group (4.2 compared with 10.7 and 8.5 compared with 3.6, respectively; P<0.05). There were no differences (P>0.05) in recovery rate, total number of CL, total recovered structures, oocytes and transferable and non-transferable embryos between groups. Serum progesterone concentrations from day 5 to 7 post-estrus were lower (P<0.05) in FGA as compared with the control group. Percentage of does with luteal failure on day 6 post-estrus was greater in FGA as compared with the control group (86.6 compared with 33.3%; P<0.01). When considering only does with luteal failure on day 6 post-estrus, mean total recovered structures, transferable embryos and percentage of does rendering > or =3 transferable embryos were greater in the FGA compared with the control group (6.3 and 1.3 structures, 4.5 and 1.2 embryos, 67 and 17%, respectively; P<0.05). In does not having luteal failure, FGA administration did not appear to affect embryo production or embryo survival. These results indicate that FGA administration after mating improves embryo recovery in dairy goats with luteal failure after superovulatory treatment. However, it also increases the incidence of luteal regression when administered early in the estrous cycle.     

Effect of extruded linseed supplementation on blood metabolic profile and milk performance of Saanen goats

This study assessed the effects of dietary supplementation with extruded linseed on milk yield and composition, milk fatty acid (FA) profile and renal and hepatic metabolism of grazing goats in mid-lactation. Forty Saanen goats were divided into two isoproductive groups: one group was fed the control diet (CON) composed of hay and pelleted concentrate and the other group was supplemented with additional 180 g/day of extruded linseed (LIN; dry matter basis), which supplied 70 g/day of fat per head for 9 weeks. Animals grazed on pasture for ∼3 h/day after the first of the 2 daily milkings. Milk samples were collected weekly and analyzed for fat, protein, lactose, milk urea nitrogen (MUN) and somatic cell count. Blood samples were collected every 2 weeks and analyzed for total bilirubin, creatinine, aspartate transaminase (AST), alanine transaminase (ALT), gamma glutamyl transpeptidase, alkaline phosphatase, total protein and urea nitrogen. Milk yield was higher in the LIN than in the CON group (2369 v. 2052 g/day). LIN group had higher milk fat (37.7 v. 33.4 g/kg) and protein (30.7 v. 29.1 g/kg) concentration and lower MUN (35.0 v. 43.3 mg/dl) than CON group. Goats fed LIN had greater proportions of 18:1 trans11, 18:2 cis9trans11 and total polyunsatured fatty acids n-3 in milk fat, because of higher 18:3n-3 and 20:5n-3 FA, and lower proportions of short- and medium-chain FAs than goats fed CON. All kidney and liver function biomarkers in serum did not differ between dietary groups, except for AST and ALT, which tended to differ. Extruded linseed supplementation to grazing mid-lactating goats for 2 months can enhance the milk performance and nutritional profile of milk lipids, without altering the general hepatic and renal metabolism.     

Changes in fatty acid profiles of thermo-intolerant and thermo-tolerant marine diatoms during temperature stress

Fatty acid composition and degree of fatty acid saturation during temperature stress in thermo-intolerant (Phaeodactylum tricornutum) and thermo-tolerant (Chaetoceros muelleri) marine diatoms were investigated. A greater number of fatty acids were observed in C. muelleri than in P. tricornutum regardless of treatment. The major fatty acids detected were 14:0, 16:0, 16:1, 16:2, 16:3, 18:0, 18:1(n-9)c, 18:2(n-6) and 20:5(n-3) with additional fatty acids 18:1(n-9)t and 20:4(n-6) detected in C. muelleri. Short duration (2 h) temperature increase above optimal growth temperature had a greater effect on fatty acid composition in C. muelleri than in P. tricornutum and the degree of fatty acid saturation was affected more by temperature in C. muelleri than in P. tricornutum during both short and long duration (24 h) treatments. Total protein assay results suggest that P. tricornutum, but not C. muelleri, was undergoing stress under our growing conditions although lipids in both diatoms were affected by increased temperature. Immunodetection of proteins with anti-rubisco indicates that the rubisco large subunit was undergoing greater turnover in C. muelleri than in P. tricornutum. However, the integrity of rubisco as a suitable indicator of lipid status needs further study. This work supports the hypothesis that a particular temperature, and not treatment duration, has the greater effect on changes in fatty acid composition. Furthermore, changes in fatty acid composition and degree of fatty acid saturation occurred more quickly in the diatoms in response to increased temperature than previously observed in nutrient starvation studies. Since diatom lipids represent an important resource for growth and reproduction of marine animals, the rapid alteration of their lipid composition under temperatures normally encountered in marine environments warrants further study.     

Effect of oilseed type on milk fatty acid composition of individual cows,and also bulk tank milk fatty acid composition from commercial farms

Supplementing dairy cow diets with oilseed preparations has been shown to replace milk saturated fatty acids (SFA) with mono- and/or polyunsaturated fatty acids (MUFA, PUFA), which may reduce risk factors associated with cardio-metabolic diseases in humans consuming milk and dairy products. Previous studies demonstrating this are largely detailed, highly controlled experiments involving small numbers of animals, but in order to transfer this feeding strategy to commercial situations further studies are required involving whole herds varying in management practices. In experiment 1, three oilseed supplements (extruded linseed (EL), calcium salts of palm and linseed oil (CPLO) and milled rapeseed (MR)) were included in grass silage-based diets formulated to provide cows with ~350 g oil/day, and compared with a negative control (Control) diet containing no supplemental fat, and a positive control diet containing 350 g/cow per day oil as calcium salt of palm oil distillate (CPO). Diets were fed for 28-day periods in a 5×4 Latin Square design, and milk production, composition and fatty acid (FA) profile were analysed at the end of each period. Compared with Control, all lipid supplemented diets decreased milk fat SFA concentration by an average of 3.5 g/100 g FA, by replacement with both cis- and trans-MUFA/PUFA. Compared with CPO, only CPLO and MR resulted in lower milk SFA concentrations. In experiment 2, 24 commercial dairy farms (average herd size±SEM 191±19.3) from the south west of the United Kingdom were recruited and for a 1 month period asked to supplement their herd diets with either CPO, EL, CPLO or MR at the same inclusion level as the first study. Bulk tank milk was analysed weekly to determine FA concentration by Fourier Transform mid-IR spectroscopy prediction. After 4 weeks, EL, CPLO and MR all decreased herd milk SFA and increased MUFA to a similar extent (average −3.4 and +2.4 g/100 g FA, respectively) when compared with CPO. Differing responses observed between experiments 1 and 2 may be due in part to variations in farm management conditions (including basal diet) in experiment 2. This study demonstrates the importance of applying experimental research into commercial practice where variations in background conditions can augment different effects to those obtained under controlled conditions.