Effect of different feeding strategies and dietary fiber levels on energy and protein retention in gestating sows.

The aim of the study was to investigate whether increased inclusion of sugar beet pulp (SBP) alters retention of fat, protein, and energy when backfat (BF) is restored in early- and mid-gestation. In total, 46 sows were fed one of four dietary treatments with increasing inclusion of SBP providing dietary fiber (DF) levels of 119, 152, 185, and 217 g/kg; sows were assigned to one of three feeding strategies (FS; high, medium, and low) depending on BF thickness at mating and again at day 30 for the following month. On days 0, 30, 60, and 108, body weight (BW) and BF thickness were measured and body pools of protein and fat were estimated using the deuterium oxide technique. On days 30 and 60, urine, feces, and blood samples were collected to quantify metabolites, energy, and nitrogen (N) balances. On days 15 and 45, heart rate was recorded to estimate heat energy. At farrowing, total born and weight of the litter were recorded. In early gestation, BW gain (P < 0.01) and body protein retention increased (P < 0.05) with increasing fiber inclusion, while body fat retention increased numerically by 59%. The increase in BF was greatest for sows fed the high FS, intermediate when fed the medium strategy, and negligible for sows fed the lowest FS (P < 0.001). Nitrogen intake, N loss in feces, and N balance increased linearly, whereas N loss in urine tended to decrease with increasing inclusion of fibers in early gestation. Concomitantly, fecal energy output and energy lost as methane increased linearly (P < 0.001), while energy output in urine declined linearly. Total metabolizable energy (ME) intake therefore increased from 36.5 MJ ME/d in the low fiber group to 38.5 MJ ME/d in the high fiber group (P < 0.01). Changing the ME towards more ketogenic energy was expected to favor fat retention rather than protein retention. However, due to increased intake of ME and increased N efficiency with increasing fiber inclusion, the sows gained more weight and protein with increasing fiber inclusion. In conclusion, increased feed intake improved both fat and protein retention, whereas increased DF intake increased protein retention.

Feeding sows sugar beet pulp (SBP) has many known benefits, for example, increased satiety and high fermentability. This study investigates the ability of the sow to utilize energy for fat retention when replacing part of starch with dietary fiber. After a demanding lactation, sows need to restore body fat, and concomitantly avoid excessive protein retention, which will increase energy demand for maintenance and risk of locomotory problems. The hypothesis in this study is that energy from fermented fibers is more efficient for fat retention than dietary starch. In the study, sows had numerically greater fat retention when fed high concentrations of fiber from SBP, but concomitantly sows unintendedly also increased their protein retention, which in turn substantially increased their body weight. Sows were allocated to one of three feeding strategies depending on their body condition score (lean, medium, or fat) in early gestation, and backfat was efficiently restored in most sows within a month. In conclusion, although gestating sows have a high capability to utilize energy from fermentable fiber, they are disposed to protein over fat retention. These aspects need to be addressed in the nutrition of modern genotype sows.

Corrigendum: A westernized diet changed the colonic bacterial composition and metabolite concentration in a dextran sulfate sodium pig model for ulcerative colitis.

[This corrects the article DOI: 10.3389/fmicb.2023.1018242.].

A westernized diet changed the colonic bacterial composition and metabolite concentration in a dextran sulfate sodium pig model for ulcerative colitis.

Introduction: Ulcerative colitis (UC) is characterized by chronic inflammation in the colonic epithelium and has a blurred etiology. A western diet and microbial dysbiosis in the colon were reported to play a role in UC development. In this study, we investigated the effect of a westernized diet, i.e., increasing fat and protein content by including ground beef, on the colonic bacterial composition in a dextran sulfate sodium (DexSS) challenged pig study. Methods: The experiment was carried out in three complete blocks following a 2×2 factorial design including 24 six-week old pigs, fed either a standard diet (CT) or the standard diet substituted with 15% ground beef to simulate a typical westernized diet (WD). Colitis was induced in half of the pigs on each dietary treatment by oral administration of DexSS (DSS and WD+DSS, respectively). Samples from proximal and distal colon and feces were collected. Results and discussion: Bacterial alpha diversity was unaffected by experimental block, and sample type. In proximal colon, WD group had similar alpha diversity to CT group and the WD+DSS group showed the lowest alpha diversity compared to the other treatment groups. There was a significant interaction between western diet and DexSS for beta diversity, based on Bray-Curtis dissimilarly. The westernized diet and DexSS resulted in three and seven differentially abundant phyla, 21 and 65 species, respectively, mainly associated with the Firmicutes and Bacteroidota phyla followed by Spirochaetota, Desulfobacterota, and Proteobacteria. The concentration of short-chain fatty acids (SCFA) was lowest in the distal colon. Treatment had a slight effect on the estimates for microbial metabolites that might have valuable biological relevance for future studies. The concentration of putrescine in the colon and feces and that of total biogenic amines was highest in the WD+DSS group. We conclude that a westernized diet could be a potential risk factor and an exacerbating agent for UC by reducing the abundance of SCFA-producing bacteria, increasing the abundance of pathogens such as Helicobacter trogontum, and by increasing the concentration of microbial proteolytic-derived metabolites in the colon.

Influence of fiber-rich coproducts on nutrient and energy digestibility and utilization in sows.

Coproducts from the food and agricultural industries can potentially be used to replace concentrated high-value grain crops in diets for sows. The coproducts are typically high in fiber and with diverse composition. Energy digestibility and utilization are generally high in sows fed fiber-rich feedstuff, but nitrogen digestion and utilization may be compromised. The purpose of this study was to quantify the apparent total tract digestibility (ATTD) of nutrients and utilization of energy and nitrogen in empty nonlactating sows fed with six different fiber-rich coproducts (FRCP). Brewers spent grain (BSG), pea hull (PH), potato pulp (PP), pectin residue (PR), sugar beet pulp (SBP), and seed residue (SR) were mixed into a basal diet (BD) with as high an inclusion level as possible, or the BD was fed solely to eight empty sows in a Youden square incomplete cross-over design. The collection period consisted of a total collection period of 5 d, of which 2 d were in a respiration chamber. The sows had a gross energy (GE) intake between 28.5 and 42.3 MJ/d; greatest for the PH fed sows and lowest for the PP fed sows. The ATTD of dry matter, organic matter, GE, and N did not differ among the BD and the PH and SBP fed sows, while the ATTDs of all nutrients and energy were intermediate for PR and BSG lowest in SR fed sows (P < 0.01). The differences were caused by variation in digestible and metabolizable energy content of the FRCP ingredients, which was lowest for SR, intermediate for PR followed by BSG and greatest for SBP, PP, and PH (P < 0.001). Total heat production (HP) did not differ among treatments but the nonactivity related HP was highest in SR fed sows and lowest in PH and SBP fed sows (P < 0.05). Retention of energy was greatest following the PH and BD (7.42 and 2.19 MJ/d, respectively), intermediate for PP, SBP, and BSG fed sows (-0.22 to -0.69 MJ/d) and lowest for the PR and SR fed sows (-4.26 and -6.17 MJ/d, respectively; P < 0.001). From a sow feeding perspective, SBP and PH have the potential to partly replace high-value grain crops due to high ATTD of all nutrients and because sows can efficiently utilize energy and protein. In contrast, SR and PR show low ATTD of nutrients and energy, thereby compromising the nutritive value. PP and BSG also have the potential to be included in sow diets, but caution should be taken because of compromised N utilization and thereby increased environmental impact.

Coproducts from the food and agricultural industries have the potential to partly substitute grain in diets for empty nonlactating sows. Many coproducts are high in fiber and with diverse fiber composition. Some being easily fermented, while others are more resistant to fermentation giving rise to a large variation in the total tract digestibility and utilization of nutrients and energy. How well fiber-rich coproducts are digested and utilized is poorly understood in sows, but it is important to ensure an optimal energy and protein composition of the feed depending on the physiological stage of the sow. This study aimed to increase knowledge on the digestibility and utilization of six fiber-rich coproducts potentially to be included in the sow's feed. We found pea hulls and sugar beet pulp suitable as grain replacers due to their high total tract digestibility and no negative effects on energy and protein utilization. Potato pulp and brewers spent grain were also well suited. However, caution should be taken in balancing diets because of increased fecal and urine nitrogen output, which will increase environmental impact. Seed and pectin residues primarily serve as gut fill.

Influence of four fiber-rich supplements on digestibility of energy and nutrients and utilization of energy and nitrogen in early and mid-gestating sows.

The digestibility of energy and nutrients in fiber-rich diets depends greatly on the fiber source but most data are from studies with growing pigs. The purpose of this study was to investigate the apparent total tract digestibility (ATTD) of nutrients in different fiber-rich diets and to quantify whole-body metabolism and utilization of energy and nitrogen (N) in gestating sows. Four fiber-rich diets based on sugar beet pulp (SBP), soy hulls (SH), palm kernel expellers (PKE), or a mixed fiber (MF) were formulated, with an average daily intake of total fiber (TF) of 471, 507, 651, and 437 g/d, respectively. A total of 48 multiparous sows were stratified by body weight at mating (day 0) and assigned to one of the four diets throughout gestation. Body weight and backfat were measured, and body pools of fat and protein were estimated using the deuterium oxide dilution technique at days 0, 30, and 60. On days 30 and 60, urine and fecal grab samples were obtained. On days 15 and 45, heart rate was measured to estimate total heat production. The ATTD of nutrients differed across treatments (P < 0.001), while in vivo organic matter digestibility deviated with up to ±3.3% units from in vitro enzyme digestibility of organic matter. The ATTD of energy was highly negatively correlated with intake of lignin (P < 0.001), while ATTD of N was highest (negatively) correlated (P < 0.001) with intake of insoluble non-starch polysaccharides (NSP). The ATTD of all nutrients except NSP was lowest in PKE-fed sows and highest, except for N, in sows fed the SBP diet. The ATTD of N was highest in the MF-fed sows and ATTD of NSP was lowest in the MF-fed sows. Sows lost most energy as heat (53% to 72% of gross energy intake), followed by energy in feces (15% to 17%), urine (3% to 4%), and methane (0.5% to 0.9%). Energy for maintenance accounted for the majority of the heat production and the total energy retention was lowest and highest in the SBP- and PKE-fed sows, with a retention of 3.3 and 13.3 MJ/d, respectively (P < 0.001). Sows lost most N through urine, the lowest and highest N loss (relative to intake) was observed in SH- and SBP-fed sows (50% to 63%, respectively), while 14% to 26% was retained as body protein. In conclusion, the fiber-rich diets were utilized efficiently by gestating sows with respect to energy with ATTD values above 82% in all four fiber-rich diets, whereas the high TF content in the diets compromised the N utilization in gestating sows.

How much energy and nutrients a pig can use from the feed depends greatly on the feed ingredients, feed level, and the physiological stage of the animal. Fibers are of great interest because they can improve health and welfare of pigs and co-products from the food and agriculture industries are among the most interesting. The ability to degrade different fiber sources and utilize energy and nutrients are poorly understood in gestating sows, but highly important when formulating the feed composition. The hypothesis was that sugar beet pulp was superior to the other three fiber-rich sources investigated: soy hulls, palm kernel expellers, or a mix of fibers, with respect to intake and utilization of energy and nutrients. We did not find sugar beet pulp to be particularly superior with respect to energy (fermentation or utilization), whereas utilization of nitrogen was highest for sugar beet pulp but compromised in the three other diets depending on fiber sources.

Bioavailability of Different Zinc Sources in Pigs 0-3 Weeks Post-Weaning.

The bioavailability of dietary zinc (Zn) in pigs may differ according to the Zn source and is affected by other components in the diet. The aim was to determine the biomarkers of Zn bioavailability (apparent total tract digestibility of Zn and serum Zn status) following six different sources of added Zn and their effect on the performance and faecal consistency score in piglets 0-3 weeks after weaning on day 28. The sources of Zn were Zn oxide (ZnO), Zn sulfate (ZnSO4), porous ZnO, Zn-glycinate, amino acid-bound Zn and hydroxy covalent-bound Zn added at 100 mg/kg (ZnO and ZnSO4 also added at 1000 mg/kg), in a total of eight treatments (n = 12/treatment). Pigs were individually housed, and titanium dioxide was included as an indigestible marker in the feed. The digestibility of Zn on day 14 post-weaning was negative for all six Zn sources at 100 mg Zn/kg, indicating insufficient Zn supply. The digestibility of Zn differed according to the Zn source, but the digestibility of Zn from ZnO and ZnSO4 did not differ between processed inorganic or chelated organic sources of Zn. However, the differences in Zn digestibility between Zn sources were not reflected as differences in the serum Zn status, feed intake, gain or probability of diarrhoea.

Determination of the Optimal Level of Dietary Zinc for Newly Weaned Pigs: A Dose-Response Study.

One hundred and eighty individually housed piglets with an initial body weight of 7.63 ± 0.98 kg (at 28 days of age) were fed a diet containing either 153, 493, 1022, 1601, 2052 or 2407 mg zinc/kg (added Zn as zinc oxide; ZnO) from day 0-21 post weaning to determine the optimal level of Zn for weaned piglets. Body weight, feed intake and faecal scores were recorded, and blood and faecal samples were collected. Dietary Zn content quadratically affected both feed intake and gain in the first two weeks, with an approximately 1400 mg Zn/kg diet and a Zn intake of 400 mg/day as the optimal levels. The relative risk of diarrhoea increased up to 60% at day 7 and 14 if serum Zn status dropped below the weaning level (767 µg/L), and maintain the weaning serum Zn status required approximately 1100 mg Zn/kg (166 mg Zn/day) during week 1. Blood markers of intestinal integrity (D-lactate and diamine oxidase) were unaffected by dietary Zn, and dietary Zn levels of 1022 and 1601 mg/kg did not affect the faecal numbers of total bacteria, Lactobacilli and E. Coli bacteria compared to 153 mg Zn/kg. These results indicate that the requirement for Zn in newly weaned piglets may be substantially higher than currently assumed.

Dietary Red Meat Adversely Affects Disease Severity in a Pig Model of DSS-Induced Colitis Despite Reduction in Colonic Pro-Inflammatory Gene Expression.

Diet plays a substantial role in the pathogenesis and management of ulcerative colitis (UC), and epidemiologic studies indicate an association between red meat intake and increased risk of UC development. Therefore, we evaluated the effect of a red meat diet on dextran sulfate sodium (DSS)-induced colitis in pigs. Weaned pigs (42 days old) were fed either a control diet or a diet substituted with 15% minced, cooked and dried beef from experimental day 0 to 14. From day 14 to 18, half of the pigs on each diet received a daily oral dose of DSS. Dietary red meat aggravated the severity of colitis based on clinical signs of disease (negative performance score) and histopathological parameters in the colon such as erosion/ulceration and the overall inflammation score but no negative effects were observed on systemic health or small intestinal permeability. Importantly, dietary meat also caused a potential beneficial reduction in the colonic expression of the pro-inflammatory cytokines IL-17A and IL-6, the pro-inflammatory enzyme PTGS2 and in the chemokine IL-8. The present study emphasizes the potential of diet to modulate mucosal inflammation and that a red meat diet might be a risk factor for the development of inflammatory bowel disease.

High-Amylose Maize, Potato, and Butyrylated Starch Modulate Large Intestinal Fermentation, Microbial Composition, and Oncogenic miRNA Expression in Rats Fed A High-Protein Meat Diet.

High red meat intake is associated with the risk of colorectal cancer (CRC), whereas dietary fibers, such as resistant starch (RS) seemed to protect against CRC. The aim of this study was to determine whether high-amylose potato starch (HAPS), high-amylose maize starch (HAMS), and butyrylated high-amylose maize starch (HAMSB)-produced by an organocatalytic route-could oppose the negative effects of a high-protein meat diet (HPM), in terms of fermentation pattern, cecal microbial composition, and colonic biomarkers of CRC. Rats were fed a HPM diet or an HPM diet where 10% of the maize starch was substituted with either HAPS, HAMS, or HAMSB, for 4 weeks. Feces, cecum digesta, and colonic tissue were obtained for biochemical, microbial, gene expression (oncogenic microRNA), and immuno-histochemical (O6-methyl-2-deoxyguanosine (O6MeG) adduct) analysis. The HAMS and HAMSB diets shifted the fecal fermentation pattern from protein towards carbohydrate metabolism. The HAMSB diet also substantially increased fecal butyrate concentration and the pool, compared with the other diets. All three RS treatments altered the cecal microbial composition in a diet specific manner. HAPS and HAMSB showed CRC preventive effects, based on the reduced colonic oncogenic miR17-92 cluster miRNA expression, but there was no significant diet-induced differences in the colonic O6MeG adduct levels. Overall, HAMSB consumption showed the most potential for limiting the negative effects of a high-meat diet.

Barley beta-glucans varying in molecular mass and oligomer structure affect cecal fermentation and microbial composition but not blood lipid profiles in hypercholesterolemic rats.

There is an unmet need for appealing and functional barley ß-glucan (BG) food matrices that can provide sufficient and active BG doses to consumers. We investigated how molecular mass and oligomer structure important for BG food and health properties affected plasma lipids and gut parameters in hypercholesterolemic rats. Following 3 weeks on a high-cholestrol diet, rats were given a high-cholesterol diet supplemented with either cellulose (control) or purified barley BGs with low (100 or 150 kDa; glucagel or lowBG, respectively) or medium (530 kDa; mediumBG) molecular masses varying in cellotriosyl/cellotetraosyl oligomer ratio for 4 weeks. All four diets (control, glucagel, lowBG or mediumBG) reduced plasma triacylglycerol and cholesterols from week 3 to 7. The BG diets increased cecal production of short-chain fatty acids (SCFAs) compared to the control diet. The glucagel and lowBG diets stimulated the number of Bifidobacterium in the cecum, whereas the mediumBG diet reduced numbers of both Bacteroides/Prevotella and Lactobacillus in the cecum compared to the control diet. In conclusion, barley BGs at 6.5-7.5% of the diet independent of molecular mass and oligomer block structure showed no additional effect compared to the control treatment on blood cholesterol and triacylglycerol levels in this hypercholesterolemic rat model. Furthermore, the cecal fermentation pattern and microbial composition did not seem to affect plasma lipid composition.

A search for synbiotics: effects of enzymatically modified arabinoxylan and Butyrivibrio fibrisolvens on short-chain fatty acids in the cecum content and plasma of rats.

Identification of dietary strategies to increase large intestinal production and absorption of short-chain fatty acids (SCFAs), especially butyrate, is of great interest due to the possible health promoting effects. We explored the effect of an enzymatically modified arabinoxylan-rich diet (EAXD) versus a Western-style control diet (WSD) low in dietary fiber with or without orally administrated Butyrivibrio fibrisolvens, a butyrate producer, on the SCFA pool in the cecal content and feces and the SCFA concentration in the blood of rats. The pool of acetate, butyrate and total SCFA was more than double in the cecal content from EAXD-fed rats compared with WSD-fed rats, and this was also reflected as an increase in portal plasma SCFA concentrations. Acetate, propionate and total SCFA concentrations were higher in mixed venous plasma following the EAXD. The number of B. fibrisolvens did not increase significantly in cecal content following administration of the bacteria. Furthermore, there was no interaction between the EAXD and B. fibrisolvens on the measured parameters.

Diets high in resistant starch and arabinoxylan modulate digestion processes and SCFA pool size in the large intestine and faecal microbial composition in pigs.

The effects of a high level of dietary fibre (DF) either as arabinoxylan (AX) or resistant starch (RS) on digestion processes, SCFA concentration and pool size in various intestinal segments and on the microbial composition in the faeces were studied in a model experiment with pigs. A total of thirty female pigs (body weight 63.1 (sem 4.4) kg) were fed a low-DF, high-fat Western-style control diet (WSD), an AX-rich diet (AXD) or a RS-rich diet (RSD) for 3 weeks. Diet significantly affected the digestibility of DM, protein, fat, NSP and NSP components, and the arabinose:xylose ratio, as well as the disappearance of NSP and AX in the large intestine. RS was mainly digested in the caecum. AX was digested at a slower rate than RS. The digesta from AXD-fed pigs passed from the ileum to the distal colon more than twice as fast as those from WSD-fed pigs, with those from RSD-fed pigs being intermediate (P< 0.001). AXD feeding resulted in a higher number of Faecalibacterium prausnitzii, Roseburia intestinalis, Blautia coccoides-Eubacterium rectale, Bifidobacterium spp. and Lactobacillus spp. in the faeces sampled at week 3 of the experimental period (P< 0.05). In the caecum, proximal and mid colon, AXD feeding resulted in a 3- to 5-fold higher pool size of butyrate compared with WSD feeding, with the RSD being intermediate (P <0.001). In conclusion, the RSD and AXD differently affected digestion processes compared with the WSD, and the AXD most efficiently shifted the microbial composition towards butyrogenic species in the faeces and increased the large-intestinal butyrate pool size.

Proliferative effect of whey from cows' milk varying in phyto-oestrogens in human breast and prostate cancer cells.

Intake of dietary phyto-oestrogens has received a great deal of attention owing to their potential influence on hormone-sensitive cancers such as breast and prostate cancer. Cows' milk contains phyto-oestrogens and the content varies according to the composition of the feed and the type and amount of legumes used. In this study we evaluated the proliferative effect of milk (whey) with different phyto-oestrogen content in human breast (MCF-7) and prostate cancer cells (PC-3). Milk was obtained from cows fed either a birdsfoot trefoil-timothy silage based ration (B1) or two different red clover silage based diets (R1 and R2) resulting in total phyto-oestrogen contents of 403, 1659 and 1434 ng/ml for the B1, R1 and R2 diets, respectively. Whey was produced from the milk and added to cell culture medium in concentrations up to 10% for MCF-7 cells and 5% for PC-3 cells. Cell proliferation was measured fluorometrically after 7 d for MCF-7 cells and 5 d for PC-3 cells. There was no significant difference in the proliferative effect of whey from the different dietary treatments at any of the whey concentrations tested. An anti-proliferative effect (P<0·01) of 5 and 10% whey was seen when tested in the presence of 10 pM oestradiol in the medium. This effect was independent of dietary treatment of cows. Whey induced a significant (P<0·01) proliferative response in PC-3 cells independent of dietary treatment. Purified equol in concentrations similar to equol concentrations in milk decreased PC-3 cell proliferation, and therefore the stimulatory effect of whey in PC-3 cells is believed to be mediated by other bioactives than equol. In conclusion, our results suggest that using whey in these proliferation assays, it was not possible to discriminate between milk with high or low levels of phyto-oestrogens.

Proliferative effect of whey from cows' milk obtained at two different stages of pregnancy measured in MCF-7 cells.

Dietary estrogens may play a role in the etiology of hormone-dependent cancers like breast cancer. Cow's milk contains various endogenous estrogens and feed derived phytoestrogens that potentially contribute to an estrogenic effect of milk in consumers, and therefore we evaluated the effect of milk (whey) in a proliferation assay with estrogen-sensitive MCF-7 human breast cancer cells. Milk samples were obtained from 22 cows representing different stages of pregnancy (first and second half) and whey was produced from the milk. 0·1, 0·25 or 0·5% whey was included in the cell culture medium and after 6 days of treatment cell proliferation was assessed by a colorimetric method with a fluorometer. Whey induced significant (P<0·05) proliferative effects compared with control cells with no added whey at all concentrations tested. There was no difference in the proliferative effect of whey depending on the stage of pregnancy from which the milk was obtained. We did not observe anti-proliferative effects when whey was tested in the presence of 10 pm estradiol in the medium. In conclusion, these results indicate that whey, irrespective of the pregnancy stage from which the milk was obtained induced a significant proliferative response in MCF-7 cells and no anti-proliferative effect, which may be caused, at least in part, by estrogens present in milk. The implications of our findings in relation to for example breast cancer will have to be studied further in other model systems preferentially in vivo.

Prepubertal exposure to cow's milk reduces susceptibility to carcinogen-induced mammary tumorigenesis in rats.

Cow's milk contains high levels of estrogens, progesterone and insulin-like growth factor 1 (IGF-1), all of which are associated with breast cancer. We investigated whether prepubertal milk exposure affects mammary gland development and carcinogenesis in rats. Sprague-Dawley rats were given either whole milk or tap water to drink from postnatal day (PND) 14 to PND 35, and thereafter normal tap water. Mammary tumorigenesis was induced by administering 7,12-dimethylbenz[a]anthracene on PND 50. Milk exposure increased circulating E2 levels on PND 25 by 10-fold (p < 0.001) and accelerated vaginal opening, which marks puberty onset, by 2.5 days (p < 0.001). However, rats exposed to milk before puberty exhibited reduced carcinogen-induced mammary carcinogenesis; that is, their tumor latency was longer (p < 0.03) and incidence was lower (p < 0.05) than in the controls. On PND 25 and 50, mammary glands of the milk-exposed rats had significantly less terminal end buds (TEBs) than the tap water-exposed controls (p < 0.019). ER-α protein levels were elevated in the TEBs and lobules of milk rats, compared to rats given tap water (p < 0.019), but no changes in cyclin D1 expression, cell proliferation or apoptosis were seen. IGF-1 mRNA levels were reduced on PND 50 in the mammary glands of rats exposed to milk at puberty. Our results suggest that drinking milk before puberty reduces later risk of developing mammary cancer in rats. This might be mediated by a reduction in the number of TEBs and lower expression of IGF-1 mRNA in the mammary glands of milk-exposed animals.

The influence of bovine milk high or low in isoflavones on hepatic gene expression in mice.

Isoflavones have generated much attention due to their potential positive effects in various diseases. Phytoestrogens especially equol can be found in bovine milk, as feed ration for dairy cows is comprised of plants containing phytoestrogens. The aim of this study was to analyze the changes in hepatic gene expression after dietary intake of milk high and low in isoflavones. In addition to pelleted feed female NMRI mice were offered water, water added either 17beta-estradiol, equol, Tween 80, and milk high and low in isoflavone content for a week. Gene expression was analyzed using an array qPCR kit. It was revealed that Tween 80 and 17beta-estradiol upregulated both phase I and phase II genes to the same extent whereas equol alone, high and low isoflavone milk did not alter the expression of phase I genes but decreased the expression of phase II genes. This study shows that dietary isoflavones can regulate the transcription of especially phase II liver enzymes which potentially could give rise to an increase in reactive oxygen metabolites that may contribute to the development of cancer.

Estrogenic activity of bovine milk high or low in equol using immature mouse uterotrophic responses and an estrogen receptor transactivation assay.

BACKGROUND: Cow's milk contain phytoestrogens especially equol depending on the composition of the feed ration. However, it is unknown whether milk differing in equol exhibits different estrogenicity in model systems and thereby potentially in humans as milk consumers. METHODS: The estrogenicity of high and low equol milk (HEM and LEM, respectively) and purified equol was investigated in immature female mice including mRNA expression of six estrogen-sensitive genes in uterine tissue. Extracts of HEM and LEM were also tested for estrogenicity in vitro in an estrogen receptor (ER) reporter gene assay with MVLN cells. RESULTS: The total content of phytoestrogens was approximately 10 times higher in HEM compared with LEM, but levels of endogenous milk estrone and 17beta-estradiol were similar in the two milk types (503-566 and 60-64.6pg/ml, respectively). There was no difference in uterine weight between mice receiving LEM and HEM, and no difference from controls. Equol (50 times the concentration in HEM) was not uterotrophic. The ERbeta mRNA expression was down-regulated in the uteri of HEM mice compared with LEM and controls, but there was no difference between milk types for any of the other genes. Extracts of HEM showed a higher estrogenicity than extracts of LEM in MVLN cells, and there was a dose-dependent increase in estrogenicity by equol. CONCLUSION: The higher in vitro estrogenicity of HEM was not reflected as a higher uterine weight in vivo although the down-regulation of ERbeta in uterine tissue of HEM mice could suggest some estrogenic activity of HEM at the gene expression level.

Effect of silage type and concentrate level on conjugated linoleic acids, trans-C18:1 isomers and fat content in milk from dairy cows.

The objective of the study was to examine how the fatty acid composition of milk especially concentrations of conjugated linoleic acids (CLA) and trans-C18:1 isomers and milk fat percentage were affected by silage type and concentrate level. Forty dairy cows were blocked and randomly assigned to one of four diets in a 2 x 2 factorial arrangement of treatments and a six week experimental period. Treatments were total mixed rations with maize (M) or grass (G) silage differing in polyunsaturated fatty acid (PUFA) profile and starch content, combined with a high (H) or a low (L) level of concentrate (with or without grain). Treatments had no significant effect on milk, protein and lactose yield, but energy corrected milk yield, milk fat percentage and fat yield was lower and protein percentage higher for maize compared with grass silage diets. Overall, maize silage diets resulted in higher concentrations of CLA isomers compared with grass silage diets, but there was a significant interaction between silage type and concentrate level for concentrations of cis9,trans11-CLA; trans10,cis12-CLA; trans11-C18:1 and trans10-C18:1. A high level of concentrate increased trans10,cis12-CLA and trans10-C18:1 and reduced cis9,trans11-CLA and trans11-C18:1 when maize but not grass silage was provided. The results suggest that high levels of concentrate (grain) do not significantly alter the pattern of PUFA biohydrogenation in the rumen, the concentration of CLA and trans-C18:1 isomers in milk or cause milk fat depression unless combined with forage naturally high in starch and C18:2n-6 such as maize silage.