RESEARCH:

Dietary fats as reproductive nutraceuticals in beef cattle - G. L. Williams2 and R. L. Stanko. Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, Beeville 78102-9410. Proc. Am. Soc. Anim. Sci., 1999.

Inadequate dietary energy intake and poor body condition are two of the most pervasive factors influencing reproductive efficiency in beef cattle production systems. Therefore, an important goal has been to discover novel methods for enhancing reproductive processes in cattle that are exposed to these conditions, often on a repeated basis. This review will examine dietary fat as a reproductive "nutraceutical," including the role of fatty acid content and minimum effective intake. Although the consumption of neutral lipids by ruminants is limited under natural conditions, the addition of digestible fats to increase caloric content or to positively modify diet physical characteristics is a long-standing practice. More recently, fat supplements have been used in attempts to influence specific metabolic pathways and, ultimately, hormones that directly modulate ovarian cellular processes. The basis for this approach lies within an array of digestive, metabolic, and reproductive sequelae that occur when cattle consume significant quantities of digestible fat. Evidence suggests that the consumption of fat by cattle, particularly polyunsaturated plant oils, can positively influence ovarian follicular growth, luteal function, and postpartum reproductive performance independent of caloric effects. Mechanistically, these effects have been attributed to a cascade of events that change rumen fermentation pat-terns, heighten lipoprotein-cholesterol synthesis, increase secretion of ovarian steroids, modify circulating concentrations of insulin and GH, and enhance the synthesis or accumulation of IGF-I in ovarian cells. Whole oilseeds, oil milling by-products, and some manufactured products are available to exploit these physiological concepts.
http://www.asas.org/jas/symposia/proceedings/0915.pdf


Effects of dietary fatty acids on reproduction in ruminants - Mattos R, Staples CR, Thatcher WW. Department of Dairy and Poultry Sciences, University of Florida, Gainesville 32611, USA. Rev. Reprod. 2000 Jan; 5(1):38-45.

Fats in the diet can influence reproduction positively by altering both ovarian follicle and corpus luteum function via improved energy status and by increasing precursors for the synthesis of reproductive hormones such as steroids and prostaglandins. Dietary fatty acids of the n-3 family reduce ovarian and endometrial synthesis of prostaglandin F2alpha, decrease ovulation rate in rats and delay parturition in sheep and humans. Polyunsaturated fatty acids such as linoleic, linolenic, eicosapentaenoic and docosahexaenoic acids may inhibit prostaglandin F2alpha synthesis through mechanisms such as decreased availability of its precursor arachidonic acid, an increased competition by these fatty acids with arachidonic acid for binding to prostaglandin H synthase, and inhibition of prostaglandin H synthase synthesis and activity. It is not known whether polyunsaturated fatty acids regulate expression of candidate genes such as phospholipase A2 and prostaglandin H synthase via activation of nuclear transcription factors such as peroxisome proliferator-activated receptors. Manipulation of the fatty acid profile of the diet can be used potentially to amplify suppression of uterine synthesis of prostaglandin F2alpha during early pregnancy in cattle, which may contribute to a reduction in embryonic mortality. Feeding fats and targeting of fatty acids to reproductive tissues may be a potential strategy to integrate nutrition and reproductive management to improve animal productivity.


Dietary fats varying in their fatty acid composition differentially influence follicular growth in cows fed isoenergetic diets - Thomas MG, Bao B, Williams GL. Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, Beeville 78102-9410, USA. J Anim Sci 1997 Sep;75(9):2512-9

The working hypothesis was that dietary fats differing in fatty acid composition would differentially influence ovarian follicular growth. Cows (n = 27) were fed isoenergetic, isonitrogenous, and isofibrous diets containing no added fat (control; CT, n = 7) or diets supplemented with fats containing primarily saturated (SAT, n = 7), polyunsaturated (PU, n = 7), or highly polyunsaturated (HPU, n = 6) fatty acids. Coincident changes in serum lipid metabolites, insulin, and GH and the concentration of IGF-I in large and medium-sized follicles also were examined. Body weights and body condition scores remained similar for all groups throughout the study. Polyunsaturated fat increased (diet x day, P = .06) the number of medium-sized follicles on d 5 through 9 of a synchronized estrous cycle within 3 wk of onset of feeding and maximized (P < .001) this to a fourfold difference at ovariectomy after 7 wk. Fats with predominantly SAT and HPU tended (P < .10) to produce these effects after 7 wk. All fat-supplemented diets increased serum concentrations of total cholesterol (P < .05), GH (P < .05), and follicular fluid IGF-I in large follicles (P < .065) compared to CT but differentially influenced serum concentrations of insulin. Polyunsaturated fat stimulated a marked increase (P < .001) in serum insulin relative to controls within 3 wk, whereas SAT and HPU increased (P < .05) serum insulin only after 6 to 7 wk. We conclude that consumption of PU fatty acids stimulates a greater rate of ovarian follicular growth in cattle compared to CT, AT, and HPU. Future research should investigate the potential role of insulin in mediating PU effects on follicular growth.
http://www.asas.org/jas/papers/1997/sep/sep2512.pdf


Fat supplementation influences postpartum reproductive performance in Brahman cows - De Fries CA, Neuendorff DA, Randel RD. Texas Agricultural Experiment Station, Overton 75684, USA. J Anim Sci 1998 Mar;76(3):864-70.

Multiparous Brahman cows (n = 40) in excellent body condition (6.5+/-.1) were randomly assigned to receive either 5.2 (rice bran) or 3.7% (control) dietary fat after calving. The experimental diets were formulated to be isocaloric and isonitrogenous. The experimental diets were fed twice daily from d 1 after calving through the first normal estrous cycle. Cows were weighed, scored for body condition, and bled at weekly intervals from d 1 through 50 after calving. Weekly bleedings continued until the first detectable estrus. Blood samples were collected daily throughout the first normal estrous cycle. All cows were exposed to a fertile bull at the estrus following the first normal estrous cycle and for a 60-d breeding season. Ovarian follicular populations were recorded weekly by transrectal ultrasonography from d 15 to 50 after calving. Calf weights were recorded at 14-d intervals from d 1 to 43 after birth and at weaning (205 d). Cows receiving rice bran gained more body condition (P < .05) than cows receiving the control supplement. The numbers of small (< 4.0 mm, P < .05), medium (4.0 to 7.9 mm, P < .05) and total follicles (P < .05) were greater in the rice bran than in the control group from 15 to 29 d after calving, and large follicles ( > or = 8.0 mm) increased in number (P < .05) and the largest follicle increased in size (P < .001) over time regardless of the level of dietary fat. Fat supplementation increased the numbers of medium (P < .01), large (P < .05), and total (P < .01) follicles and size of the largest follicle (P < .05) during the 3 wk before the first normal estrous cycle. The intervals from parturition to reproductively important end points were similar (P > .10) between dietary treatments as well as the percentage of cows showing normal or abnormal estrous cyclic activity. Treatment did not affect (P > .10) daily serum progesterone (P4) concentrations. However, there was a tendency (P = .09) for more rice bran-supplemented cows to be pregnant (94.1 vs 71.4%) after being exposed to a fertile bull for 60 d. Calf weight gain tended to be higher (P = .08) in calves nursing rice bran-supplemented dams. In conclusion, using rice bran, with high concentrations of oleic and linoleic acids, as a fat supplement for postpartum cows enhanced ovarian follicular growth before normal estrous cycles resumed and increased body condition scores and pregnancy rates without altering postpartum interval or serum P4 concentrations.
http://www.asas.org/jas/papers/1998/mar/mar864.pdf


Effects of altering dietary fatty acid composition on prostaglandin synthesis and fertility - Abayasekara DR, Wathes DC. Reproduction and Development Group, Department of Veterinary Basic Sciences, Royal Veterinary College, London, UK. Prostaglandins Leukot Essent Fatty Acids 1999 Nov;61(5):275-87.

Several studies over the past 20 years have demonstrated that subjects on diets composed of substances with high levels of n-3 polyunsaturated fatty acids (PUFAs) (e.g. fish) have a decreased incidence of heart disease. On this basis, a recent report from the Department of Health has advised UK consumers to decrease the proportion of saturated as opposed to unsaturated fats in their diet and to increase the ratio of n-3 to n-6 PUFAs. This could be achieved by altering the amounts of these constituents in milk and meat. n-3 Fatty acids can most easily be added to animal feed as either fish oil or linseed oil and can be increased in the blood and milk of ruminants following protection to avoid hydrogenation in the rumen. In western countries the ratio of consumption of n-6 to n-3 PUFAs is greater than 10 and current evidence tends to suggest that a ratio nearer 5 would be more desirable and compatible with cardiovascular well being. As fertility in the UK dairy herd is already poor, it is important to establish whether alterations in dietary n-3 and n-6 PUFAs affects herd fertility before widespread changes in animal diets are recommended. Therefore, this review considers the role played by PUFAs and eicosanoids in fertility, with particular reference to the implications for farm livestock production. The evidence reviewed shows that alteration of the concentration and ratio of n-6 and n-3 PUFAs in feeds can influence prostaglandin synthesis/metabolism in a number of mammalian systems. The changed patterns of prostaglandin synthesis can as a consequence, affect the diverse functions (e.g. hormone secretion) that are normally mediated via prostaglandins. Similarly, changes in prostaglandin synthesis effected through manipulation of PUFAs has a major bearing on fertility (as PGs affect many reproductive parameters, e.g. ovulation). Several studies in cattle and other mammals, show that feeding or infusing different types of fat with varying PUFA content to females can alter: the number and size of ovarian follicles, the ovulation rate, progesterone production by the corpus luteum, the timing of luteolysis and gestational length. In the male most recent work has focussed on sperm production and experiments in fowl have demonstrated clear effects of dietary PUFAs on both the sperm membrane phospholipid composition and on fertilizing ability.


Influence of supplemental fats on reproductive tissues and performance of lactating cows - Staples CR, Burke JM, Thatcher WW. Department of Dairy and Poultry Sciences, University of Florida, Gainesville 32611, USA. J Dairy Sci 1998 Mar;81(3):856-71.

Fat supplementation (about 3% of dietary dry matter) has often positively influenced the reproductive status of the dairy cow, including increased size of the ovulatory follicle, increased numbers of ovarian follicles, increased plasma concentration of progesterone, reduced secretion of prostaglandin metabolite, increased lifespan of the corpus luteum, and improved fertility. Supplemental fat may allay partially negative energy status during the early postpartum period, yet often the positive reproductive influence of supplemental fat has been independent of the energy status of the cow. The fatty acid profile of supplemental fats is influential to their impact. Linoleic acid and eicosapentaenoic acid (found in fish meal) are proven inhibitors of cyclooxygenase in endometrial tissue of dairy cows. As a result, endometrial secretion of PGF alpha can be suppressed, thus potentially preventing early embryonic death. This process may be aided by the effect fat has in suppressing estradiol-17 beta secretion, thus reducing uterine PGF2 alpha secretion and decreasing the sensitivity of the corpus luteum to PGF2 alpha. Targeting of dietary fatty acids toward ovarian and uterine function may enhance efficiency of reproductive management and fertility.
http://www.adsa.org/jds/papers/98/ds98856.pdf


Plasma fatty acids, prostaglandin F2alpha metabolite, and reproductive response in postpartum heifers fed rumen bypass fat - Filley SJ, Turner HA, Stormshak F., Department of Animal Sciences, Oregon State University, Corvallis 97331, USA. J Anim Sci 2000 Jan;78(1):139-44.

An experiment was conducted to determine whether feeding rumen-protected fatty acids (FA) to postpartum heifers would increase plasma concentrations of linoleic acid and PGF2, metabolite (PGFM), shorten the interval from calving to first increase in plasma concentrations of progesterone (P4), and increase pregnancy rate relative to controls. Hereford x Angus heifers (346 kg) were assigned randomly to treatments containing either lipid or barley supplemented diets for the first 30 d postpartum. Lipid was .23 kg.heifer(-1).d(-1) of calcium salts of FA (CSFA; n = 20), and an isocaloric amount of barley served as the control (n = 19). Supplements, with .23 kg of barley as a vehicle, and a basal diet of meadow and alfalfa hays were pen fed to heifers (5/pen). Heifers were bled on alternate days (d1 to 30) and twice weekly (d 30 to 2 wk after first estrus) for RIA of plasma PGFM and P4, respectively. Weight percentage of major FA in plasma on d1 and 7 was determined with gas chromatography. First behavioral estrus was detected by use of intact bulls and confirmed by an increase in plasma P4. On d 7, but not d 1, plasma from heifers fed CSFA had altered proportions of major FA (P < .01), including an increase in linoleic acid compared with those of controls (29.1 vs 25.6% of total FA; SE = .75; P < .01). Analysis of variance of contrast variables revealed an effect of treatment on direction of change in PGFM from d 3 to 5 (P < .01). By d 7 and on d 9, plasma concentrations of PGFM were greater in heifers fed CSFA than in controls (P = .02 and P = .06, respectively). There was no difference in plasma concentration of PGFM between treatments on d 1, 3, 5, 11, 13, and 15 postpartum (P = .80, .17, .52, .82, .46, and .77, respectively). Days to first estrus with ovulation, pregnancy rate, and calving interval were not affected by treatments (P = .58, .52, and .24, respectively). Although supplemental lipid fed to primiparous beef heifers increased plasma levels of linoleic acid and production of PGFM in the early postpartum period, it did not improve the fertility of these heifers in the subsequent breeding season.
http://www.asas.org/jas/papers/2000/sep2244.pdf


Effects of dietary fat and sire breed on puberty, weight, and reproductive traits of F1 beef heifers - Lammoglia MA, Bellows RA, Grings EE, Bergman JW, Bellows SE, Short RE, Hallford DM, Randel RD. BovaGen, San Antonio, TX 78216, USA. J Anim Sci 2000 Sep;78(9):2244-52.

Prepubertal F1 heifers (n = 246; from crossbred dams bred to either Hereford H, Limousin L, or Piedmontese P sires) were fed 1.9% (LF) or 4.4% (HF) dietary fat from 254+/-4 d of age until they reached puberty or the breeding season started. Safflower seeds (37% oil with 79% linoleic acid) were the added fat source. Blood samples and backfat thickness measurements were obtained from 60 randomly selected heifers representing the sire breeds and diets studied. In addition, five H-sired heifers from both diets were serially bled at 28-d intervals. Total gain, ADG, body condition score, and backfat thickness were affected by sire breed (P < 0.001) but not diet. Backfat thickness was affected (P < 0.01) by the diet x time on feed interaction. Diet did not affect pubertal age (P > 0.10) but tended (P = 0.08) to affect the percentage of heifers pubertal by the beginning of breeding (June 4). Sire breed effects on puberty age at beginning of breeding, percentage pubertal at the beginning of breeding, and puberty age during the entire study were all highly significant. The effect of the diet x sire breed interaction on percentage of heifers pubertal at beginning of breeding (P < 0.05) was 74.4 vs 76.3% in H-sired, 69.8 vs 60.5% in L-sired, and 76.2 vs 97.6% in P-sired heifers (LF vs HF, respectively). Number of AI services per pregnancy and final pregnancy percentage were not affected by diet or the diet x sire breed interaction. Diet affected progesterone (P < 0.05) and cholesterol (P < 0.001) concentrations, and sire breed tended to affect (P = 0.06) cholesterol concentrations. The effect of the diet x time on feed interaction on cholesterol concentrations was highly significant. There were no effects of diet or sample period on insulin or growth hormone concentrations in serially collected blood samples. We conclude that effects of supplemental dietary fat may be breed-dependent and hypothesize that a feeding period of approximately 60 d duration may be more appropriate than the 162 d used in this study.
http://www.asas.org/jas/papers/2000/sep2244.pdf



PRACTICAL APPLICATIONS:

Effect of Fishmeal Supplementation of First Service Conception Rates in Young Lactating Beef Cows - T.R. Bonnette, P.D. Burns, J.C. Whittier, D. Davidson, D.B. Abbey, and D. Schutz. 2000 Research Report. The Department of Animal Sciences Colorado State University

The objective of this experiment was to determine if fishmeal supple- mentation increased first service conception rates in young lactating beef cows. Lactating first-calf beef cows were fed a corn silage based diet that was supplemented with either corn gluten meal or fishmeal (n=20/treatment). First service conception rates were 20% higher in cows supplemented with fishmeal compared to cows supplemented with corn gluten meal. However, due to the small number animals used in this study, there was not a significant (P = .22) effect. Overall pregnancy rates did not differ between treatment groups (P > .10). Preliminary results from this experiment indicated that fishmeal supplementation may be an effective way to increase conception rates in lactating beef cows.
http://ansci.colostate.edu/ (full text article is located in the reproduction section of beef cattle publications)


Soybean diet helps cows get pregnant - Forrest Rose, University of Missouri.
Chris Zumbrunnen, University of Missouri regional livestock specialist, admits even he has a hard time believing the results from feeding raw soybeans to beef cows before calving season. He boosted the first-service conception rate 14% at rebreeding time -- just by feeding raw soybeans for 45 days.
http://www.agriculture.com/default.sph/AgNews.class?FNC=DetailNews__Asearch_listAgNews_html___43693


Whole soybeans boost beef rebreeding rates - Duane Dailey, Senior Writer, University of Missouri
Feeding whole unprocessed soybeans to cows in late pregnancy boosts rebreeding rates, said Chris Zumbrunnen, regional extension livestock specialist at Milan, MO. Feeding 3.5 pounds of whole beans per day increased both first-service conception rates and overall pregnancy in beef herds. Zumbrunnen told of University of Missouri research and farmer experience at a calving clinic, Jan. 12, at the MU Forage Systems Research Center.
http://www.agriculture.com/default.sph/AgNews.class?FNC=DetailNews__Asearch_listAgNews_html___47156

Response to dietary fat may depend on breed - Beef
Feeding a high-fat diet may increase the percentage of heifers pubertal by the start of the breeding season. But, the diet effect interacts with heifer breed, so the response may depend on breed, say researchers at the USDA Agricultural Research Service (ARS). The study found heifers with a low-fat body composition may have a different dietary fat requirement than heifers with a greater body fat composition.
http://industryclick.com/magazinearticle.asp?releaseid=3462&magazinearticleid=27745&siteid=5&magazineid=13

Feeding Raw Soybeans to Cattle - Dan B. Faulkner, Extension Beef Specialist, University of Illinois
Soybean prices are at their lowest level in 25 years because of large worldwide soybean production. Cattle producers might be able to economically feed ground raw soybeans to beef cattle. Generally, if the cost of soybeans is below 94% the cost of soybean meal (SBM), they can economically be included in beef diets to replace soybean meal.
http://beefnet.outreach.uiuc.edu/fulltext.cfm?section=2&documentID=80

Vegetable-based fat supplements - Clint Peck, Beef
Vegetable-based fat supplements, such as soybean oil, play an ever-increasing role in cattle nutrition. Cattle feeders have known for years that fat is a great source of energy. Cow/calf producers are catching on to that lesson now, too. Those ranchers are also learning that today's vegetable-based fat supplements offer some great potential benefits in cattle rations.
http://industryclick.com/magazinearticle.asp?releaseid=8402&magazinearticleid=118105&siteid=5&magazineid=13

Fat supplements for reproduction - John Maday, Drovers
Adequate energy is a key nutritional requirement for reproductive efficiency in beef cows. University of Nebraska Beef Specialist Ivan Rush notes that producers typically supplement cows with grain as an energy source, but fat could be a cost-effective alternative.
http://www.drovers.com/archives/article.ihtml?id=1333

Fat and fertility - Drovers
Research indicates that supplementing fat to young beef cows can improve pregnancy rates, according to Colorado State University Animal Scientist Patrick Burns. Results are particularly encouraging when the source is fish meal high in omega-3 fatty acids.
http://www.drovers.com/archives/article.ihtml?id=762