Effects of milk diets containing beef tallow or coconut oil on the fatty acid metabolism of liver slices from preruminant calves

Effects of medium-chain fatty acids and tributyrin supplementation in milk replacers on growth performance, blood metabolites, and hormone concentrations in Holstein dairy calves

This study aimed to evaluate the effects of triglycerides containing medium-chain fatty acids (MCT) and tributyrin (TB) supplementation in a milk replacer (MR) on growth performance, plasma metabolites, and hormone concentrations in dairy calves. Sixty-three Holstein heifer calves (body weight at 8 d of age, 41.1 ± 2.91 kg; mean ± SD) were randomly assigned to 1 of 4 experimental MR (28% crude protein and 18% fat): (1) containing 3.2% C8:0 and 2.8% C10:0 (in fat basis) without TB supplementation (CONT; n = 15), (2) containing 6.7% C8:0 and 6.4% C10:0 without TB supplementation (MCT; n = 16), (3) containing 3.2% C8:0 and 2.8% C10:0 with 0.6% (dry matter basis) TB supplementation (CONT+TB; n = 16), (4) containing 6.7% C8:0 and 6.4% C10:0 with 0.6% TB supplementation (MCT+TB; n = 16). The MR were offered at 600 g/d (powder basis) from 8 to 14 d, up to 1,300 g/d from 15 to 21 d, 1,400 g/d from 22 to 49 d, down to 700 g/d from 50 to 56 d, 600 g/d from 57 to 63 d, and weaned at 64 d of age. All calves were fed calf starter, chopped hay, and water ad libitum. The data were analyzed using a 2-way ANOVA via the fit model procedure of JMP Pro 16 (SAS Institute Inc.). Medium-chain fatty acid supplementation did not affect the total dry matter intake. However, calves that were fed MCT had greater feed efficiency (gain/feed) before weaning (0.74 ± 0.098 vs. 0.71 ± 0.010 kg/kg) compared with non-MCT calves. The MCT calves also had a lower incidence of diarrhea compared with non-MCT calves during 23 to 49 d of age and the weaning period (50 to 63 d of age; 9.2% vs. 18.5% and 10.5% vs. 17.2%, respectively). Calves fed with TB had a greater total dry matter intake during postweaning (3,465 vs. 3,232 g/d). Calves fed TB also had greater body weight during the weaning (90.7 ± 0.97 vs. 87.9 ± 1.01 kg) and postweaning period (116.5 ± 1.47 vs. 112.1 ± 1.50 kg) compared with that of non-TB calves. The plasma metabolites and hormone concentrations were not affected by MCT or TB. These results suggest that MCT and TB supplementation in the MR may improve the growth performance and gut health of dairy calves.

Effects of Coconut Oil and Palm Oil on Growth, Rumen Microbiota, and Fatty Acid Profile of Suckling Calves

This study aimed to evaluate the effects of coconut oil and palm oil in milk replacer (MR) on the growth performance, blood lipids, rumen fermentation, rumen microbiota, and fatty acid profile of hepatic and muscle of suckling calves. Thirty-six Holstein male calves were randomly assigned to three treatments. Three milk replacers containing different fat sources were as follows: control group (CON, milk fat), coconut oil group (CCO, coconut oil powder as fat), and palm oil group (PLO, palm oil powder as fat). Calves were weighed and blood sampled at 14, 28, 42, and 56 days old, respectively, and the feed intake and fecal score were recorded daily. Fat sources in milk replacers had no effects on body weight, ADG, DMI, fecal score, or days of abnormal fecal in suckling calves among the three groups, while the PLO group tended to decrease starter intake compared with the other groups. Serum concentrations of TC, HDL-C, LDL-C, and VLDL-C in the CCO group increased compared with those of the CON group. Palm oil also decreased the serum GLU concentration of calves but had no effects on serum lipids compared with milk fat. Coconut oil or palm oil had no effects on rumen fermentation, rumen chyme enzyme activity, rumen bacterial community richness and diversity, and dominant phyla and genera when compared with milk fat. However, compared with the CON group, the CCO group increased the proportion of MCFAs and n-6 PUFAs, and decreased the proportion of UFAs and MUFAs in liver tissue, while the PLO group increased the proportion of PUFAs and decreased the proportion of n-3 PUFAs in liver tissue. In addition, compared with the CON group, the CCO group increased the proportion of MCFAs, and decreased the proportion of UFAs and n-3 PUFAs in longissimus dorsi, while the PLO group increased the proportion of PUFAs and decreased the proportion of n-3 PUFAs in longissimus dorsi. In conclusion, compared with milk fat, coconut oil or palm oil in MR had no effects on growth performance, rumen fermentation, and rumen microflora but significantly increased serum lipids concentration and changed some proportions of MCFAs and PUFAs in liver and longissimus dorsi in suckling calves. These results indicate that coconut oil or palm oil as the sole fat source for MRs has no adverse effect on calf rumen fermentation and rumen microbiota but has a detrimental effect on n-3 PUFAs deposition in the liver and longissimus dorsi muscle.

When Two plus Two Is More than Four: Evidence for a Synergistic Effect of Fatty Acids on Peroxisome Proliferator-Activated Receptor Activity in a Bovine Hepatic Model

The inclusion of fat in livestock diets represents a valuable and cost-effective way to increase the animal’s caloric intake. Beyond their caloric value, fatty acids can be understood in terms of their bioactivity, via the modulation of the ligand-dependent nuclear peroxisome proliferator-activated receptors (PPAR). Isotypes of PPAR regulate important metabolic processes in both monogastric and ruminant animals, including the metabolism of fatty acids (FA), the production of milk fat, and the immune response; however, information on the modulation of bovine PPAR by fatty acids is limited. The objective of this study was to expand our understanding on modulation of bovine PPAR by FA, both when used individually and in combination, in an immortalized cell culture model of bovine liver. Of the 10 FA included in the study, the greatest activation of the PPAR reporter was detected with saturated FA C12:0, C16:0, and C18:0, as well as phytanic acid, and the unsaturated FA C16:1 and C18:1. When supplemented in mixtures of 2 FA, the most effective combination was C12:0 + C16:0, while in mixtures of 3 FA, the greatest activation was caused by combinations of C12:0 with C16:0 and either C18:0, C16:1, or C18:1. Some mixtures display a synergistic effect that leads to PPAR activation greater than the sum of their parts, which may be explained by structural dynamics within the PPAR ligand-binding pocket. Our results provide fundamental information for the development of tailored dietary plans that focus on the use of FA mixtures for nutrigenomic purposes.

Jersey calf performance in response to high-protein, high-fat liquid feeds with varied fatty acid profiles: blood metabolites and liver gene expression

Most available Jersey calf milk replacers (CMR) use edible lard as the primary fat source, which lacks medium-chain fatty acids (MCFA). However, Jersey cow milk consists of over 10% MCFA. The objective of this trial was to determine whether altering the fatty acid profile of CMR by increasing the amount of MCFA would alter liver lipid infiltration, liver gene expression, and blood metabolites when fed to Jersey calves. Fifty Jersey calves were fed 1 of 4 diets: pasteurized saleable whole milk (pSWM) from Jersey cows [27.9% crude protein (CP), 33.5% fat, dry matter (DM) basis]; CMR containing 100% of fat as edible lard (100:00; 29.3% CP, 29.1% fat, DM basis); CMR containing 20% of fat as coconut oil (CO; 80:20; 28.2% CP, 28.0% fat); or CMR containing 40% of fat as CO (60:40; 28.2% CP, 28.3% fat). Liquid diet DM intake averaged 0.523, 0.500, 0.498, and 0.512 kg/d for pSWM, 100:00, 80:20, and 60:40, respectively. Calves were fed their assigned liquid diet daily at 0600 and 1800 h from 2 d of age until 7 wk of age, and once daily until 8 wk of age. Calves were taken off trial at 9 wk of age. Calves had access to water and grain (23.8% CP, 2.71% fat, DM basis). Grain DM intake averaged 0.386, 0.439, 0.472, and 0.454 kg/d for pSWM, 100:00, 80:20, and 60:40, respectively. Liver biopsy cores were obtained from 15 calves at 42 d of age (pSWM, n=4; 100:00, n=4; 80:20, n=3; 60:40, n=4) and from 4 baseline calves <2d of age. Liver biopsy cores were used for histological appraisal of lipid infiltration and gene expression analyses of short-, medium-, and long- chain acyl-coenzyme A dehydrogenases, sterol regulatory element binding transcription factor 1, acetyl coenzyme A carboxylase, and fatty acid synthase. Lipid infiltration and expression of selected genes were not different among diets. After an overnight fast, weekly blood samples were taken immediately before feeding at 0600 h via jugular venipuncture in all calves. Serum and plasma obtained from blood samples were used in the analyses of total protein, glucose, triglycerides, nonesterified fatty acids, and plasma urea nitrogen (PUN). Nonesterified fatty acids and PUN were the only blood metabolites affected solely by diet. Nonesterified fatty acids decreased in a linear manner with increased dietary CO inclusion. Calves fed pSWM had higher PUN than calves fed 80:20. In this trial, altering the fatty acid profile of CMR with the addition of medium-chain fatty acids from CO had minimal effects on liver lipid infiltration, liver gene expression, and blood metabolites when fed to Jersey calves.

Long-chain fatty acids differentially alter lipogenesis in bovine and caprine mammary slices

Indirect comparisons from studies in vivo have suggested that caprine mammary tissue is less sensitive than bovine mammary tissue to the anti-lipogenic effect of long-chain fatty acids (LCFA), including specific rumen biohydrogenation (RBH) intermediates of polyunsaturated fatty acids (PUFA). Our objective was to investigate the effects on lipogenesis of 18-carbon LCFA differing in the degree of unsaturation and/or double bond conformation using cultured slices of bovine and caprine mammary tissues. Mammary tissues were collected from five multiparous Holstein × Normande cows and six multiparous Alpine goats in mid lactation. The expression of genes involved in milk component synthesis was measured in tissues collected at slaughter and after slice preparation: FASN, SCD1, CD36, SREBF1 and PPARG1 mRNA levels were higher in bovine than caprine samples, whereas the opposite was observed for CSN2 mRNA levels. Bovine and caprine mammary slices were incubated for 20 h in a medium with BSA (control), cis-9-18 : 1, 18 : 2n-6, 18 : 3n-3, cis-9, trans-11-CLA, or trans-10, cis-12-CLA (the latter at 3 increasing concentrations: C1 (0.11 mm), C2 (0.16 mm), C3 (0.37 mm)). Lipogenesis was estimated by measuring the incorporation of 14C-acetate into total lipid. Significant differences of individual LCFA (P < 0.05) were observed between species: bovine tissue showed a decrease in total lipogenesis with 18 : 2n-6, 18 : 3n-3, trans-10,cis-12-CLA (C2 and C3) while caprine tissue showed an increase after treatment with 18 : 3n-3, cis-9, trans-11-CLA or trans-10, cis-12-CLA (C3). These results were not related to the mRNA abundance of our set of genes in the mammary slices after incubation. In conclusion, this study demonstrates that caprine mammary slices reacted differently from bovine mammary slices to the anti-lipogenic activity of specific LCFA and suggests that regulation of lipogenesis via other genes and/or at protein level and enzyme activity may be involved.

Effects of the peroxisome proliferator-activated receptor-alpha agonists clofibrate and fish oil on hepatic fatty acid metabolism in weaned dairy calves

Peroxisome proliferator-activated receptor-alpha (PPARalpha) agonists increase fatty acid oxidation in liver of nonruminants. If similar effects occur in dairy cattle, enhanced hepatic oxidative capacity could decrease circulating nonesterified fatty acids and hepatic triacylglycerol accumulation in periparturient cows. The objectives of this study were 1) to determine whether partitioning of fatty acid metabolism by liver slices from weaned Holstein calves treated with PPARalpha agonists in vivo is altered compared with partitioning by liver slices from control (untreated) calves, and 2) to measure in vitro metabolism of palmitate and oleate by bovine liver slices and relate these to mRNA abundance for key enzymes. Weaned male Holstein calves (7 wk old; n=15) were assigned to 1 of 3 groups for a 5-d treatment period: control (untreated), clofibrate (62.5 mg/kg of BW), or fish oil (250 mg/kg of BW). Calves treated with clofibrate consumed less dry matter. Body weight, liver weight, liver weight:body weight ratio, blood nonesterified fatty acids, beta-hydroxybutyrate, and liver composition were not significantly different among treatments. Liver slices were incubated for 2, 4, and 8 h to determine in vitro conversion of [1-(14)C] palmitate and [1-(14)C] oleate to CO(2), acid-soluble products, esterified products, and total metabolism. In liver slices incubated for 8 h, conversion of palmitate to CO(2) was greater for calves treated with clofibrate compared with control calves or calves treated with fish oil. Conversion of palmitate to esterified products, total palmitate metabolism, and metabolism of oleate were not different among treatments. Conversion of palmitate to CO(2) was greater than that from oleate for all treatments, but rates of total metabolism did not differ. Clofibrate increased or tended to increase liver expression of several PPARalpha target genes involved in fatty acid oxidation (e.g., ACADVL, ACOX1, CPT1A), whereas fish oil did not significantly affect genes associated with fatty acid oxidation but tended to increase DGAT1. Overall, our data indicated that bovine liver responded to clofibrate treatment but not fish oil, although increases in hepatic lipid metabolism were much less than those reported in rodents treated with clofibrate or fish oil. Applications of PPARalpha agonists may be of interest to increase the rate of hepatic fatty acid oxidation and decrease triacylglycerol accumulation in periparturient dairy cows.

In vitro metabolism of rumenic acid in bovine liver slices

Ruminant products are the major source of CLA for humans. However, during periods of fat mobilization, the liver might play an important role in CLA metabolism which would limit the availability of the latter for muscles and milk. In this context, rumenic acid (cis-9, trans-11 CLA) metabolism in the bovine liver (n = 5) was compared to that of oleic acid (n = 3) by using the in vitro liver slice method. Liver slices were incubated for 17 h in a medium containing 0.75 mM of FA mixture and 55 microM of either [1-(14)C] rumenic acid or [1-(14)C] oleic acid at 37 degrees C under an atmosphere of 95% O(2)-5% CO(2). Rumenic acid uptake by liver slices was twice (P = 0.009) that of oleic acid. Hepatic oxidation of both FA (> 50% of incorporated FA) led essentially to the production of acid-soluble products and to a lower extent to CO(2) production. Rumenic acid was partly converted (> 12% of incorporated rumenic acid) into conjugated C18:3. CLA and its conjugated derivatives were mainly esterified into polar lipids (71.7%), whereas oleic acid was preferentially esterified into neutral lipids (59.8%). Rumenic acid secretion as part of VLDL particles was very low and was one-fourth lower than that of oleic acid. In conclusion, rumenic acid was highly metabolized by bovine hepatocytes, especially by the oxidation pathway and by its conversion into conjugated C18:3 for which the biological properties need to be elucidated.

Effects of Vegetable Fats Versus Lard in Milk Replacers on Feed Intake, Digestibility, and Growth in Finnish Ayrshire Bull Calves

The aim was to study whether vegetable fat mixtures could be used instead of lard [15.2% in dry matter (DM)] in milk replacers without impairing the performance of Finnish Ayrshire bull calves (n = 58). The growth performance of the calves was measured before and after weaning from 14 d to 6 mo of age. The following 3 fat sources in a milk replacer were studied: 1) a mixture of palm, coconut, and rapeseed oil, 2) palm and coconut oil, and 3) lard. The calves were bucket-fed 2 L of milk replacer 3 times per day. The milk replacer contained 116 g of DM/L, resulting in an average DM intake of 4.8 g of DM/kg of body weight0.75 (BW0.75) during the 8-wk trial, after which the calves were weaned. All the calves had free access to water, commercial starter, and grass silage before weaning. The weaned calves had free access to water and grass silage and were given 3 kg/d (air-dry basis) of a commercial concentrate mixture. The concentrate was replaced by barley when the bulls were 4.5 mo old. There were no significant differences between the diets in feed intake and apparent diet digestibility. The health and BW of the calves were similar during the study. The feed conversion rate (kg of DM intake/kg of gain) before weaning was significantly greater for the lard diet compared with the 2 vegetable fat mixtures. After weaning, the feed conversion rate was slightly lower for the diet that included the palm, coconut, and rapeseed oil mixture than for the diet that included palm and coconut oil mixture. The study showed that the 2 mixtures consisting solely of vegetable oils were effective dietary components, thus providing 2 alternative fat mixtures of milk replacers, for use instead of lard in formulating commercial calf milk replacers.

Vaccenic acid metabolism in the liver of rat and bovine

Hepatic metabolism of vaccenic acid (VA), especially its conversion into CLA, was studied in the bovine (ruminant species that synthesizes CLA) and in the rat (model for non-ruminant) by using the in vitro technique of liver explants. Liver tissue samples were collected from fed animals (5 male Wistar rats and 5 Charolais steers) and incubated at 37 degrees C for 17 h under an atmosphere of 95% O2/5% CO2 in medium supplemented with 0.75 mM of FA mixture and with 55 microM [1-14C]VA. VA uptake was about sixfold lower in bovine than in rat liver slices (P< 0.01). For both species, VA that was oxidized to partial oxidation products represented about 20% of VA incorporated by cells. The chemical structure of VA was not modified in bovine liver cells, whereas in rat liver cells, 3.2% of VA was converted into 16:0 and only 0.33% into CLA. The extent of esterification of VA was similar for both animal species (70-80% of incorporated VA). Secretion of VA as part of VLDL particles was very low and similar in rat and bovine liver (around 0.07% of incorporated VA). In conclusion, characteristics of the hepatic metabolism of VA were similar for rat and bovine animals, the liver not being involved in tissue VA conversion into CLA in spite of its high capacity for FA desaturation especially in the rat. This indicates that endogenous synthesis of CLA should take place exclusively in peripheral tissues.

Small Intestine and Liver Microsomal Triacylglycerol Transfer Protein in the Bovine and Rat: Effects of Dietary Coconut Oil

The bovine liver is characterized by a chronic low capacity to secrete triacylglycerols (TAG). In situations favoring their hepatic synthesis, such as coconut oil feeding, TAG accumulate, leading to a lipid infiltration in the liver of preruminant calves. To assess the possible role of the microsomal TAG transfer protein (MTP) in this phenomenon and to put into evidence a tissue-specific regulation in the bovine species, we compared by Western blot the content in both MTP subunits in the liver and in different portions of the small intestine in preruminant calves and in growing rats receiving coconut oil or beef tallow as the sole source of fat in the diet. The pattern of MTP distribution was similar between calf and rat tissues, the jejunum being the major site for both MTP expression and intestinal absorption of dietary lipid endproducts. Concentrations of the MTP large and small subunits were 10- to 20-fold lower and 2- to 3-fold lower, respectively, in calf than in rat tissues, including the liver. Coconut oil in the diets of calves and rats did not significantly affect the expression of MTP large subunits even though TAG content was strongly increased 12-fold in the calf liver. These results clearly indicated that calf liver handled fat metabolically in a manner different from rat liver. However, present experimental conditions did not allow proof that MTP was directly related to the accumulation of fat in calf liver.

Effects of dietary coconut oil on apolipoprotein B synthesis and VLDL secretion by calf liver slices

Incorporation of coconut oil (CO) rich in lauric acid into the milk diet induces a lipid infiltration of the liver (steatosis) in 1-month-old calves. Among possible steps involved in diet-induced liver steatosis, the ability of the calf liver to synthesize apolipoprotein (Apo) B and to secrete it as part of VLDL particles was investigated. Liver samples were taken from calves fed for 17 d on a conventional milk replacer containing CO (n 5) and beef tallow (BT, n 4) as reference. Samples were cut into slices 0.5 mm thick and subsequently incubated for 12 h in a medium containing a [(35)S]methionine-[(35)S]cysteine mix and 0.8 mm-sodium laurate or oleate, the major fatty acids of CO and BT diets respectively. Concentrations of total [(35)S]proteins, [(35)S]albumin and [(35)S]ApoB in liver cells were 2-fold lower 0.0004 and 0.03 respectively) in CO- than in BT-fed calves. Although the total amount of proteins secreted (including albumin) was similar in both groups of calves, the amount of VLDL-[(35)S]Apo secreted was 2-fold lower (P = 0.004) in CO- than in BT-fed calves. These results suggest that a CO-enriched milk diet induces in preruminant calves a lipid infiltration of the liver by decreasing ApoB synthesis, leading to a reduction in secretion of VLDL particles.