Fatty Acids In Milk Fat Research Articles

Dietary supplementation of rumen native microbes improves lactation performance and feed efficiency in dairy cows

Objectives were to determine the effects of 2 dietary microbial additives supplemented to diets of Holstein cows on productive performance and feed efficiency. One-hundred and 17 Holstein cows were enrolled at 61 d (31 to 87 d) postpartum in a randomized complete block design experiment. Cows were blocked by parity group, as nulliparous or multiparous cows and, within parity, by pre-treatment energy-corrected milk yield. Within block, cows were randomly assigned to one of 3 treatments administered as top-dress for 140 d. Treatments consisted of either 100 g of corn meal containing no microbial additive (CON; 15 primiparous and 25 multiparous), 100 g of corn meal containing 5 g of a mixture of Clostridium beijerinckii and Pichia kudriavzevii (G1; 4 × 107 cfu of C. beijerinckii and 1 × 109 cfu of P. kudriavzevii; 14 primiparous and 24 multiparous), or 100 g of corn meal containing 5 g of a mixture of C. beijerinckii, P. kudriavzevii, Butyrivibrio fibrisolvens, and Ruminococcus bovis (G2; 4 × 107 cfu of C. beijerinckii, 1 × 109 cfu of P. kudriavzevii, 1 × 108 cfu of B. fibrisolvens, and 1 × 108 cfu of R. bovis; 15 primiparous and 24 multiparous). Intake of DM, milk yield, and BW were measured daily, whereas milk composition was analyzed at each milking 2 d a week, and body condition was scored twice weekly. Milk samples were collected on d 60 and 62 in the experiment and analyzed for individual fatty acids. The data were analyzed with mixed-effects models with orthogonal contrast to determine the impact of microbial additive (MA; CON vs. 1/2 G1 + 1/2 G2) and type of microbial additive (TMA; G1 vs. G2). Results are described in sequence as CON, G1, and G2. Intake of DM (22.2 vs. 22.4 vs. 22.4 kg/d), BW (685 vs. 685 vs. 685 kg) and the daily BW change (0.40 vs. 0.39 vs. 0.39 kg/d) did not differ among treatments; however, feeding MA tended to increase BCS (3.28 vs. 3.33 vs. 3.36). Supplementing MA increased yields of milk (39.9 vs. 41.3 vs. 41.5 kg/d), ECM (37.9 vs. 39.3 vs. 39.9 kg/d), fat (1.31 vs. 1.37 vs. 1.40 kg/d), total solids (4.59 vs. 4.75 vs. 4.79 kg/d), and ECM per kg of DMI (1.72 vs. 1.76 vs. 1.80 kg/kg). Furthermore, cows fed MA increased yields of pre-formed fatty acids in milk fat (>16C; 435 vs. 463 vs. 488 g/d), particularly unsaturated fatty acids (367 vs. 387 vs. 410 g/d), such as linoleic (C18:2 cis-9, cis-12; 30.9 vs. 33.5 vs. 35.4 g/d) and α-linolenic acids (C18:3 cis-9, cis-12, cis-15; 2.46 vs. 2.68 vs. 2.82 g/d) on d 60 and 62 in the experiment. Collectively, supplementing G1 and G2 improved productive performance of cows with no differences between the 2 MA.

Effects of saturated fatty acids with lysophospholipids on production and nutrient digestibility in lactating cows

The objective of the experiment was to determine the effects of supplemental saturated fatty acid (SFA) sources, lysophospholipids (LPL), and their interaction on production and nutrient digestibility in lactating dairy cows. The experiment was conducted with 48 cows in a randomized complete block design. Cows were blocked (total 12 blocks) by parity and days in milk and randomly assigned to 4 dietary treatments in each block (2 × 2 factorial arrangement), i.e., 2 sources of fat supplements, C16:0 (palmitic acid, PA)- or C18:0 (stearic acid, SA)-enriched fat, with or without LPL. The experiment was conducted for 6 wk to measure daily dry matter intake and milk yield and weekly milk composition. During the last week of the experiment, spot fecal and urine samples were collected to determine total-tract nutrient digestibility. Milk samples in the last week were also collected to analyze for milk fatty acid (FA) profile. All data were analyzed using the mixed procedure of SAS where block was used as a random effect and FA, LPL, and the interaction of FA by LPL were used as fixed effects. Week and interactions of week by FA or LPL were included for production measures. Different sources of SFA did not affect dry matter intake and milk yield. However, PA increased (39.7 vs. 36.8 kg) energy-corrected milk compared with SA due to increased milk fat yield. No effect of LPL on production measures was observed. Total-tract digestibilities of dry matter, organic matter, crude protein, and total FA were not different between PA and SA, but PA increased (41.4 vs. 38.8%) neutral detergent fiber digestibility compared with SA. Supplementation of LPL increased (64.7 vs. 60.5%) total FA digestibility, especially 18-carbon FA (74.1 vs. 68.2%). An interaction of SFA by LPL was found for 16-carbon FA digestibility. The PA diet increased the concentration of 16-carbon FA in milk fat and SA increased the concentration of preformed FA (≥18 carbons). Supplementation of LPL decreased the concentration of trans-10 C18:1. No difference in N utilization and excretion among treatments was observed. In conclusion, PA was more effective in improving milk fat yield of lactating cows compared with SA. Supplementation of LPL increased digestibility of total FA, especially 18-carbon FA but did not affect production.

Определение взаимосвязи генотипов SNP с содержанием жирных кислот различной пространственной конфигурации в молоке коров

Abstract. Milk fat is the third main source of lipids for human nutrition. Fatty acids in milk fat have a heterogeneous composition due to differences in chain length, degree of saturation, etc. It has been scientifically proven that long-term consumption of trans-fatty acids causes various diseases of the human body; according to WHO recommendations, their maximum consumption should not exceed 1 % of total energy. A comprehensive study of the composition of fatty acids in cattle milk gives scientists the opportunity to use this trait in breeding work by selecting genotypes with a low content of trans-isomers and saturated fatty acids harmful to human health. The scientific novelty lies in the study of molecular genetic mechanisms for regulating the quantitative content of fatty acids and their trans-isomers in the fat fraction of cow's milk. The purpose of the work is to identify allelic variants of SNPs associated with the fatty acid composition of cow's milk and the content of trans isomers of unsaturated fatty acids in it. Research methods. The studies were carried out on cows of the Holstein black-and-white breed. The genetic profile of animals of the Holstein black-and-white breed was studied, SNPs significantly associated with the quantitative and qualitative content of fatty acids and their trans-isomers in the fat fraction of cow's milk were identified. The fatty acid composition of cows' milk was determined using a multiparameter automatic analyzer MilkoScan 7/Fossomatic 7 FT+ / DC (FOSS, Denmark). Results. Whole-genome genotyping was performed. Analyzing the content of fatty acids with different saturation of hydrogen bonds, a significant difference between the amount of fatty acids and genotypes, reliable values were established only for 5 SNPs. It was found that for four SNPs, the highest values of the content of fatty acids and trans-isomers were in homozygous genotypes ARS-BFGL-NGS-41348GG; BTA-115852-no-rsAA; BTB-00771463GG; Hapmap46159-BTA-70956TT. A significant difference in the content of trans-fatty acid isomers in milk between genotypes was found only for SNP ARS-BFGL-NGS-5502. The largest mass fraction of trans-isomers of unsaturated fatty acids was found in the milk fat of cows with the heterozygous genotype AG, which amounted to 0.076 g/100 g and was 0.011 g/100 g and 0.032 g/100 g (P≤0.01) more compared to heterozygous genotypes GG and AA, respectively.

Effects of reduced levels of organic trace minerals in proteinate forms and selenium yeast in the mineral mix on lactation performance, milk fatty acid composition, nutrient digestibility, and antioxidant status in dairy goats.

The objective was to evaluate the effects of replacing inorganic trace minerals (ITM) with reduced levels of organic trace minerals (OTM) in proteinate forms and selenium yeast (Se-yeast) in the mineral premix of prepartal and lactating dairy goats on lactation performance, milk fatty acid (FA) composition, nutrient digestibility, and antioxidant status. Xinong Saanen dairy goats (n = 40) were blocked by parity and body weight, and randomly assigned to either ITM or OTM treatments from 4wk prepartum to 8 mo of lactation. Both groups received the same basal diet except for the trace mineral supplement. The ITM supplement included Fe, Cu, Zn, and Mn as sulfates, and Se as selenite to meet the recommendations. The OTM supplement included Fe, Cu, Zn, and Mn as proteinates at 50% of ITM supplement levels, and Se as Se-yeast at 100% of ITM supplement level. Sampling and measurements were performed in the first, second, fourth, and eighth month of lactation. Data were summarized by month and treatment, and analyzed using the Mixed Model of SPSS with repeated measures. OTM group showed lower milk fat (P = 0.02) and higher milk Se (P = 0.03) with no compromised effects on milk yield and milk protein compared to ITM group. Furthermore, OTM decreased the content of C6:0, C8:0, and C10:0 (P < 0.05) and increased the content of odd- and branched-chain FAs in milk fat due to greater content of C15:0 (P = 0.01) and anteiso C15:0 (P = 0.07). OTM led to greater total tract digestibility of dry matter (P = 0.03), crude protein (P = 0.07), ether extract (P = 0.03), and acid detergent fiber (P = 0.05). OTM goats showed less fecal excretion of Fe (P = 0.01), Cu (P < 0.01), and Zn (P = 0.08) compared to ITM goats. There was a tendency for greater serum GSH-Px activity (P = 0.09) with OTM. Overall, the long-term substitution of reduced levels of OTM for ITM can change milk fat and FA composition while maintaining milk yield, digestibility, and antioxidant status.

Identification of SNPs associated with the content of saturated and unsaturated fatty acids in cow milk

The fatty acids in milk fat have a heterogeneous composition due to differences in chain length, their saturation degree, etc. Fatty acids with the number of carbon atoms in the chain from 10 to 14 are considered carriers of the unique taste of dairy products, in particular cheese and butter. In addition, medium-chain fatty acids are used in the treatment of newborn children, as well as adults with disorders of: triglyceride hydrolysis in the small intestine and the process of their absorption, chronic pancreatitis, congenital celiac disease, chronic enteritis, etc. A comprehensive study of the composition of fatty acids in cattle milk provides an opportunity to use this feature in breeding work by selecting genotypes to obtain raw materials with specified properties.

Novel methodology to enrich medium- and short-chain fatty acids in milk fat to improve metabolic health.

Dietary short- and medium-chain fatty acids have been shown to elevate circulating ketone bodies and confer metabolic health benefits. Cow milk fat contains these lipids in a balanced mix but in relatively low concentrations. Enriching them could amplify health benefits of dairy products. Here, we used a volatility-based workflow to produce milk fat with a 2-fold enrichment of medium- and short-chain fatty acids (referred to as MSFAT). Our proof-of-concept studies in mice demonstrated that intake of MSFAT increased circulating ketone bodies, reduced blood glucose levels, and suppressed food intake. In humans, ingestion of MSFAT resulted in increased circulating ketone bodies, trended to attenuate (p = 0.07) postprandial glucose excursion, and acutely elevated energy expenditure. Our findings show that milk products enriched with MSFAT may hold significant metabolic advantages.

Lactational performance, enteric methane emission, and nutrient utilization of dairy cows supplemented with botanicals

The objective of this study was to evaluate lactational performance, enteric gas emissions, ruminal fermentation, nutrient use efficiency, milk fatty acid profile, and energy and inflammatory markers in blood of peak-lactation dairy cows fed diets supplemented with Capsicum oleoresin or a combination of Capsicum oleoresin and clove oil. A 10-wk randomized complete block design experiment was conducted with 18 primiparous and 30 multiparous Holstein cows. Cows were blocked based on parity, days in milk, and milk yield (MY), and randomly assigned to 1 of 3 treatments (16 cows/treatment): (1) basal diet (CON); (2) basal diet supplemented with 300 mg/cow per day of Capsicum oleoresin (CAP); and (3) basal diet supplemented with 300 mg/cow per day of a combination of Capsicum oleoresin and clove oil (CAPCO). Premixes containing ground corn (CON), CAP, or CAPCO were mixed daily with the basal diet at 0.8% of dry matter intake (DMI). Supplementation of the diet with CAP or CAPCO did not affect DMI, MY, milk components, and feed efficiency of the cows. Body weight (BW) was increased during the last 2 wk of the experiment by CAP and CAPCO, compared with CON. The botanicals improved BW gain (0.85 and 0.66 kg/d for CAP and CAPCO, respectively, compared with -0.01 kg/d for CON) and CAP enhanced the efficiency of energy utilization, compared with CON (94.5% vs. 78.4%, respectively). Daily CH4 emission was not affected by treatments, but CH4 emission yield (per kg of DMI) and intensity (per kg of MY) were decreased by up to 11% by CAPCO supplementation, compared with CON and CAP. A treatment × parity interaction indicated that the CH4 mitigation effect was pronounced in primiparous but not in multiparous cows. Ruminal molar proportion of propionate was decreased by botanicals, compared with CON. Concentrations of trans-10 C18:1 and total trans fatty acids in milk fat were decreased by CAP and tended to be decreased by CAPCO, compared with CON. Total-tract apparent digestibility of nutrients was not affected by treatments, except for a tendency for decreased starch digestibility in cows supplemented with botanicals. Blood concentrations of β-hydroxybutyrate, total fatty acids, and insulin were not affected by botanicals. Blood haptoglobin concentration was increased by CAP in multiparous but not in primiparous cows. Lactational performance of peak-lactation dairy cows was not affected by the botanicals in this study, but they appeared to improve efficiency of energy utilization and partitioned energy toward BW gain. In addition, CH4 yield and intensity were decreased in primiparous cows fed CAPCO, suggesting a potential positive environmental effect of the combination of Capsicum oleoresin and clove oil supplementation.

РЫЖИК ПОСЕВНОЙ В РАЦИОНЕ ДОЙНЫХ КОРОВ

Milk cows need high metabolic energy sources that are often to be found among plant crops with high fat content. This study featured Camelina sativa, an oilseed crop, as an energy supplement in the diet of lactating cows: 5 % thermally-treated C.sativa seeds were introduced into the grain feed mix. The experiment lasted 35 days and increased the total polyunsaturated fatty acids in milk fat by 1.1 % while the fat content in the milk increased by 0.35 %. The average daily milk yield increased by 3.7 %.

Caprine milk fatty acid responses to dietary dried grape pomace

Including grape pomace in goat diets presents a potentially valuable strategy for enhancing the sustainability of goat farming and mitigating environmental risks. This work aimed to investigate the impact of dietary dried grape pomace (DGP) on milk yield, milk composition and milk fatty acid (FA) profile in goats. Gas chromatography was utilised to obtain an extensive profile of FA in milk fat. Dry matter intake, as well as milk yield and composition were not altered by dietary DGP. Despite the predominance of linoleic acid (LA, 18:2 cis-9,cis-12) in the lipids of DGP and the presence of phenolic compounds, its inclusion in the diet did not negatively affect the quantitatively main groups of FA. Furthermore, there was no significant impact on butyric, caproic, caprylic, and capric acids, the major 18:1 trans isomers, including vaccenic acid (18:1 trans-11), LA, α-linolenic acid (18:3 n-3), and the long chain polyunsaturated n-6 and n-3 FA. However, rumenic acid in milk fat was significantly reduced from 0.36 to 0.30 g/100 g of total fatty acid methyl esters. This study supports that up to 6%, DGP can be safely included in conventional dairy goat diets without compromising the production results or altering to great extent the milk FA profile.

Effects of dietary forage-to-concentrate ratio and forage type on milk phospholipids and fatty acid composition of polar lipids

The effects of grass silage and red clover silage on milk fatty acid (FA) composition are extensively studied, but little is known of their effects on minor lipid constituents of milk fat globule membrane. We investigated the effects of forage:concentrate (FC) ratio in grass silage-based diets and forage type (grass silage vs. red clover silage) on selected molecular species of milk phospholipids (PL) and the FA composition of PL. Ten multiparous Nordic Red cows were offered following dietary treatments: grass silage-based diets containing 70:30 (HG) or 30:70 (LG) FC ratio or a red clover silage-based diet (RC) comprising 50:50 FC ratio on a dry matter basis. The most abundant molecular species within the phosphatidylcholines was 16:0-18:1 phosphatidylcholine that was increased by 18% in HG compared with LG milk. Dietary treatments did not affect the relative proportion of 18:1-18:1+18:0-18:2 phosphatidylethanolamine that was the most prevalent species (ca. 44%-45%) in that class. We identified the d18:1-22:0 sphingomyelin as the most abundant sphingomyelin species that tended to increase in HG milk compared with LG. The FC ratio did not affect the relative proportions of saturated FA nor monounsaturated FA in PL, but the proportion of cis-9 18:1 was elevated in HG versus LG milk, whereas the proportion of 18:2n-6 was 50% higher in LG versus HG milk. The RC diet increased monounsaturated FA and 18:3n-3 levels in PL compared with grass silage-based diets and decreased the relative proportion of saturated FA. However, the RC diet did not affect the relative proportion of polyunsaturated FA in PL, although red clover silage typically increases the proportion of polyunsaturated FA in milk fat. This study provides valuable knowledge of the minor lipid components in milk on species level in relation to common feeding strategies in high-forage systems.

Lactation performance, milk fat output, and nutrient digestibility responses to the addition of liquid molasses or yeast culture in dairy cows fed super-conditioned corn

Increased diet fermentability may decrease ruminal pH and fiber digestibility, and increase the flow of trans fatty acids (FA) to the lower tract ultimately leading to milk fat depression. We recently showed that feeding super-conditioned corn, a new method of corn processing (95°C for 6 min in super-conditioner) for ruminants has potential to the reduction in milk fat yield caused by changes in ruminal pH and increased trans FA in milk fat. Supplementing yeast culture (YC) and replacing starch with sugar sources in diet can counteract the negative effects of high fermentable diets by improving ruminal pH and milk fat output. This study aimed to evaluate the effect of feeding beet liquid molasses (LM) and YC on intake and total-tract digestibility of nutrients, milk yield and composition, ruminal fermentation, milk FA profile, and plasma concentrations of glucose, nonesterified FA, β-hydroxybutyric acid, and urea N in early-lactation dairy cows fed high-starch diets containing super-conditioned corn. Twelve primiparous and 18 multiparous Holstein cows (mean ± SD; 67 ± 12 d in milk and 42 ± 2.1 kg of milk at the beginning of the experiment) were blocked by parity, pre-experimental milk yield, and DIM. Cows were used in a randomized complete block design experiment with 14 d as covariate period and 37 d for the experimental period. The following dietary treatments were fed as total mixed rations: (1) control diet (CTRL = no YC or LM supplementation), (2) LM supplementation at 5% of the diet dry matter (MOL diet), and (3) CTRL supplemented with 10 g/d of YC (YST diet). Diets were formulated to be isonitrogenous and isoenergetic. Intake of nutrients and apparent total-tract digestibility of crude protein and starch did not change across treatments. In contrast, cows fed the YST diet had the greatest apparent total-tract digestibility of dry matter, organic matter and neutral detergent fiber. Compared with the CTRL diet, yield of 4% FCM increased by 2.4 and 1.8 kg in cows fed MOL or YST, respectively. The ruminal molar proportions of acetate and butyrate increased in cows fed the YST or MOL diets, respectively, but the proportion of ruminal propionate was not affected by treatments. Milk fat concentration increased by supplementing both LM and YC and the milk yield of total trans-18:1 dropped by 45% and 18% relative to CTRL with MOL or YST diets, respectively. While the MOL diet increased the milk proportion and yield of de novo FA, no treatment effects were observed for the proportion and yield of preformed FA in the milk fat. Apart from β-hydroxybutyric acid concentration in plasma, which was greatest in cows fed MOL, remaining blood metabolites were not affected by treatments. Overall, MOL and YST diets increased 4% FCM and milk fat concentration and reduced the proportion of total trans-18:1 FA in milk fat in cows fed a concentrate based on super-conditioned corn. These responses were associated with increased ruminal pH and the molar proportions of acetate and butyrate with feeding the MOL and YST diets.

Photoluminescence Spectral Patterns and Parameters of Milk While Souring

For the efficient production and processing of milk, it is important to control its quality indicators. Optical spectroscopy, in combination with statistical analysis methods, can be a useful method of evaluation due to its speed, non-invasiveness, and relative cheapness. This investigation is aimed at studying of the interrelations of the spectral patterns, the absorption parameters, and the photoluminescence values of cow’s milk during its souring. The spectral characteristics of excitation and photoluminescence were measured on a diffraction spectrofluorometer in the range of 200–500 nm. For establishing an effective control procedure during milk souring, the most informative method is found to be the use of the excitation wavelengths of 232 nm, 322 nm, 385 nm and 442 nm. These ranges correspond to the amino acids of milk proteins, the fatty acids of milk fat, and the aromatic fragments of vitamins. When using the photoluminescence flux ratios Φ232/Φ322 and Φ385/Φ442, linearly approximated dependences on acidity can be obtained with determination coefficients of 0.88–0.94. The proposed photoluminescent method can be used as a non-destructive and fast-acting tool for monitoring the properties of milk during fermentation, as well as for the subsequent creation of a portable and inexpensive sensor based on this method.

Lipid peroxidation in sheep and cow traditional butter obtaind from southern Tehran, Iran

Butter is popularly known in dairy products and consists of large amounts of milk fat (at least 80%). The risk of oxidation increases by a higher content of unsaturated fatty acids in milk fat and adversely affects the quality and safety of the product. Primary oxidation products are hydroperoxides, which can decompose to form lower molecular weight compounds such as alcohols, aldehydes, free fatty acids (FFA), and ketones. This process may give rise to butter rancidity. In this study, 20 samples of traditional butter, including 10 samples of cow butter and 10 samples of sheep butter, were purchased from different traditional dairy product supermarkets in southern Tehran and were analyzed to evaluate the amount of fat oxidation.The peroxide levels in all samples of traditional butter were within the permissible limit established by Iran's national standard. According to the results, it was found that the amount of peroxide in cow butter (1.08 ± 0.12 mEq/kg) is higher than in sheep butter (p=0.037). It may be related to the temperature and time of storage. Therefore, strategies such as diminishing temperatures, maintaining products in a dark environment, removing oxygen by creating a vacuum in the packaging, and using antioxidant compounds can prevent butter oxidation.

Milk triglycerides from dairy cows abomasally infused with increasing amounts of high-oleic sunflower fatty acids

The triglyceride composition of milk fat largely determines the manufacturing characteristics of products containing milk fat. Increasing oleic acid content of milk fat might be desirable for human nutrition and also for butter and whipping cream, among other product applications. The objective of this research was to determine the effects of increasing intestinally available oleic acid (provided via abomasal infusion) on the profile of milk triglycerides. A control and 4 increasing doses of free fatty acids from high oleic sunflower oil (HOSFA) were infused into the abomasum of 4 lactating dairy cows in a changeover experimental design with periods of 7 d. Treatments were (1) control (no fatty acids infused), (2) HOSFA (250 g/d), (3) HOSFA (500 g/d), (4) HOSFA (750 g/d), and (5) HOSFA (1,000 g/d). All treatments included meat solubles and Tween 80 as emulsifiers. Infusion of HOSFA increased oleic acid and decreased short- and medium-chain fatty acids in milk fat. Statistical analysis of results showed linear changes in most of the milk triglycerides analyzed. The most significant changes as the result of increasing HOSFA infusion were a decrease in triglycerides with saturated fatty acids (butyrin-caprylin-palmitin, butyrin-laurin-olein, butyrin-myristin-palmitin, butyrin-palmitin-palmitin, caproin-myristin-palmitin, butyrin-palmitin-stearin, caproin-palmitin-palmitin) and an increase in dioleyl triglycerides (with butyric, lauric, myristic and palmitic acids) and triolein. The synthesis of triglyceride is position-specific and does not follow a random distribution model.

Effects of phytonutrients and yeast culture supplementation on lactational performance and nutrient use efficiency in dairy cows

Yeast culture and phytonutrients are dietary supplements with distinct modes of action, and they may have additive effects on the performance of dairy cattle. The objective of this study was to investigate the effects of a preparation of phytonutrients and a yeast culture from Saccharomyces cerevisiae on lactational performance, total-tract digestibility of nutrients, urinary nitrogen losses, energy metabolism markers, and blood cells in dairy cows. Thirty-six mid-lactation Holstein cows (10 primiparous and 26 multiparous) were used in an 8-wk randomized complete block design experiment with a 2-wk covariate period, 2 wk for adaptation to the diets, and a 4-wk experimental period for data and samples collection. Following a 2-wk covariate period, cows were blocked by days in milk, parity, and milk yield and randomly assigned to 1 of 3 treatments (12 cows per treatment): basal diet supplemented with 14 g/cow per day yeast culture (YC; S. cerevisiae), basal diet supplemented with 1.0 g/cow per day phytonutrients (PN; 5.5% cinnamaldehyde, 9.5% eugenol, and 3.5% capsicum oleoresin), or basal diet supplemented with a combination of YC and PN (YCPN). Treatments were top-dressed once daily on the total mixed ration at time of feeding. Dry matter intake, milk yield, and feed efficiency were not affected by treatments. Milk composition and energy-corrected milk yield were also not affected by supplementation of YC, PN, and YCPN. There were no differences in intake or total-tract digestibility of dietary nutrients among treatments. Compared with YC, the PN and YCPN treatments tended to decrease the proportion of short-chain fatty acids in milk fat. There was an additive effect of YC and PN supplementation on urinary urea nitrogen (UUN) excretion relative to total nitrogen intake. Cows fed a diet supplemented with YCPN had lower UUN excretion than cows in YC and tended to have lower UUN excretion compared with PN. Blood monocytes count and percentage were decreased in cows fed PN and YCPN diets compared with YC. Treatments did not affect concentrations of blood β-hydroxybutyrate and total fatty acids. Overall, lactational performance, digestibility of nutrients, energy metabolism markers, and blood cells were not affected by YC, PN, or YCPN supplementation. A combination of PN and YC had an additive effect on nitrogen excretion in dairy cows.

Effect of supplementation of oilseeds co-products on production performance and fatty acids composition of Beetal goats.

This study evaluated the effect of different oilseed co-product supplementations on feed intake, nutrient digestibility, N retention, yields of milk and milk constituents, and milk fatty acid (FA) profile of Beetal goats. In the lactation trial, thirty-six lactating multiparous Beetal goats (45 ± 2.04kg; 15 ± 2.3days in milk) were assigned to four experimental rations according to randomized complete block design. The blocks were balanced for daily milk yield, parity, and body weight. The goats were either fed a maize silage and wheat straw-based basal ration ad libitum (control) or the control ration was supplemented with cotton seed cake, mustard seed cake, or maize oil cake on an iso-N basis. At the end of lactation trial, four goats (44 ± 0.8kg BW; producing 1250 ± 110g milk/day) were selected and moved to individual metabolism crates for a digestibility and N balance experiment, using a Latin square design (4 × 4). Supplementation of the co-products increased intakes of forage mixture (P = 0.002), total dry matter (DM; P < 0.001), neutral detergent fibre (NDF; P = 0.003), and crude protein (CP; P < 0.001). The additional N supplied by the co-products increased (P < 0.001) N retention, yields of milk, fat, protein, and lactose. Further comparison of the rations supplemented with the co-products revealed that the greatest (P < 0.05) increase in yields of milk (240g/day), milk protein (11.6g/day), fats (16.3g/day), and lactose (11.2g/day) was recorded for maize oil cake, as compared to the control. Except C8:0, supplementation of the co-products decreased (P < 0.01) the contents of all de novo-synthesized saturated FAs (SFAs) and increased (P < 0.001) the contents of health beneficial C18:1n-9, C18:1 tans-11, C18:2n-6, C18:3n-3, C20:2n-6, C20:5n3, and total unsaturated FAs in milk fat. Our findings demonstrated that the oilseed co-product inclusion in dairy goat rations significantly improves forage biomass utilization, yields of milk and milk constituents, and milk FAs' profile, with the largest impact being observed for maize oil cake.

Effect of 2-hydroxy-4-(methylthio)butanoate (HMTBa) on milk fat, rumen environment and biohydrogenation, and rumen protozoa in lactating cows fed diets with increased risk for milk fat depression.

Biohydrogenation-induced milk fat depression (MFD) is a reduction in milk fat synthesis caused by bioactive fatty acids (FA) produced during altered ruminal microbial metabolism of unsaturated FA. The methionine analog 2-hydroxy-4-(methylthio)butanoate (HMTBa) has been shown to reduce the shift to the alternate biohydrogenation pathway and maintain higher milk fat yield in high-producing cows fed diets lower in fiber and higher in unsaturated FA. The objective of this experiment was to verify the effect of HMTBa on biohydrogenation-induced MFD and investigate associated changes in rumen environment and fermentation. Twenty-two rumen cannulated high-producing Holstein cows [168 ± 66 d in milk; 42 ± 7 kg of milk/d (mean ± standard deviation)] were used in a randomized design performed in 2 blocks (1 = 14 cows, 2 = 8 cows). Treatments were control (corn carrier) and HMTBa (0.1% of diet dry matter). The experiment included a 7-d covariate period followed by 3 phases that fed diets with increasing risk of MFD. The diet during the covariate and low-risk phase (7 d) was 32% neutral detergent fiber with no additional oil. The diet during the moderate-risk phase (17 d) was 29% neutral detergent fiber with 0.75% soybean oil. Soybean oil was increased to 1.5% for the last 4 d. The statistical model included the random effect of block and time course data were analyzed with repeated measures including the random effect of cow and tested the interaction of treatment and time. There was no effect of block or interaction of block and treatment or time. There was no overall effect of treatment or treatment by time interaction for dry matter intake, milk yield, and milk protein concentration and yield. Overall, HMTBa increased milk fat percent (3.2 vs. 3.6%) and yield (1,342 vs. 1,543 g/d) and there was no interaction of treatment and dietary phase. Additionally, HMTBa decreased the concentration of trans-10 18:1 in milk fat and rumen digesta. Average total ruminal concentration of volatile FA across the day and total-tract dry matter and fiber digestibility were not affected by HMTBa, but HMTBa increased average rumen butyrate and decreased propionate concentration and increased total protozoa abundance. Additionally, HMTBa increased the fractional rate of α-linoleic acid clearance from the rumen following a bolus predominantly driven by a difference in the first 30 min. Plasma insulin was decreased by HMTBa. In conclusion, HMTBa prevented the increase in trans FA in milk fat associated with MFD through a mechanism that is independent of total volatile FA concentration, but involves modification of rumen biohydrogenation. Decreased propionate and increased butyrate and ruminal protozoa may also have functional roles in the mechanism.

Odd- and branched-chain fatty acids in milk fat from Holstein dairy cows are influenced by physiological factors

Dairy products are the major source of odd- and branched-chain fatty acids (OBCFAs), a group of nutrients with emerging health benefits. The animal diet is known to influence milk fat OBCFAs of dairy cows; however, little is known about the effects of physiological factors. The objective of this study was to investigate the effects of parity and lactation stage on OBCFAs in milk fat of dairy cows. Holstein dairy cows (n = 157) were selected according to parity (first, second, third, or greater) and days in milk (DIM) (≤21 DIM, 21 < DIM ≤ 100, 100 < DIM ≤ 200, >200 DIM). All cows were fed the same total mixed ration for three weeks. Milk samples were collected during the last three days of each lactation stage for fatty acid (FA) analyses via gas chromatography. Results showed that first- and second-parity cows displayed significantly higher proportions and yields of iso-14:0, iso-15:0, iso-16:0, total iso-FA, and total branched-chain FA (P < 0.05) compared with other parities. The proportions of C17:0 and C17:1 cis-9 were also greater in first-parity cows (P < 0.05), while the yields of C17:0 and C17:1 cis-9 were similar among different parities (P > 0.05). The proportions of total OBCFAs were greater in first- and second-parity cows (P < 0.05), whereas the highest yield was observed in second-parity cows. Lactation dairy cows in ≤ 21 DIM group displayed lower proportions of iso-13:0, anteiso-13:0, C13:0, iso-14:0, C15:0, iso-16:0, total iso-FA, and total OBCFAs compared with that of the other groups (P < 0.05), and also lower yields of iso-14:0 and iso-16:0 (P < 0.05). In contrast, C17:0 and C17:1 cis-9 proportions and yields were higher in dairy cows with ≤ 21 DIM (P < 0.05). Iso-17:0 and anteiso-17:0 were not affected by lactation stage (P > 0.05). Taken together, our data showed that both parity and lactation stage have considerable effects on milk fat OBCFAs of dairy cows. In summary, first- and second-parity cows had higher milk OBCFAs compared with later parity cows, and OBCFAs with medium chain lengths were lower in dairy cows with ≤ 21 DIM, while C17:0 and C17:1 cis-9 were higher. These findings show that milk OBCFA contents are differentially modulated by physiological state. They will be useful in future studies that seek to alter OBCFA composition of Holstein dairy cow milk fats.

Changing the grazing session from morning to afternoon or including tannins in the diet was effective in decreasing the urinary nitrogen of dairy cows fed a total mixed ration and herbage

Our aim was to evaluate whether increasing soluble carbohydrates in the herbage by changing the time of the grazing session or including Acacia mearnsii tannin in the diet would affect intake, digestion, N partitioning, and productive performance of dairy cows fed a diet combining ryegrass herbage with partial total mixed ration (PMR). We hypothesized that both strategies could reduce the concentration of NH3-N in the rumen, reducing urinary N excretion. Nine Holstein cows were used in a triplicate 3 × 3 Latin square experiment with 3 experimental periods of 22 d. The cows were fed a fixed amount of PMR [60% of the predicted individual dry matter intake (DMI)], and an unrestricted amount of herbage in 1 grazing session of 5 h/d. The treatments were (1) morning grazing session and afternoon PMR meal (AM); (2) morning PMR meal and afternoon grazing session (PM); and (3) morning grazing session and afternoon PMR meal supplemented with 15.0 g of tannins/kg of PMR dry matter (TAN). Milk production was not affected by treatments. Although the protein concentration was lower for TAN than for PM, no differences were detected for the yield of any component between treatments. The concentration of individual or grouped fatty acids in milk fat was not affected by treatments, except for 16:1 cis-9 and Δ9-desaturase ratios 14:1/14:0 and 16:1/16:0, which were lower for TAN. Treatments did not affect total DMI, but PM tended to increase herbage DMI and reduce dry matter and crude protein digestibilities. Treatments did not affect cow eating and ruminating behavior except for the proportion of time spent eating PMR, which was higher for PM and TAN. Although no relevant effects of treatments on ruminal fermentation, purine derivatives excretion in urine, or N excretion in milk were detected, both PM and TAN decreased the total N excreted in urine by an average of 8% compared with AM. In conclusion, changing the grazing session from the morning to the afternoon and including tannins in the diet were effective in decreasing the excretion of urinary N but did not change the productive performance of dairy cows fed PMR and ryegrass herbage.

Replacing corn with full-fat corn germ in a basal diet containing cactus (Opuntia stricta) cladodes and sugarcane as forage sources induces milk fat depression associated with the trans-10 shift in dairy cows

Recent evidence indicates that associating cactus Opuntia cladodes with plant oils represents a promising strategy to increase the nutritional value of milk fat. This study aimed to investigate the effects of full-fat corn germ (FFCG), as an alternative to plant oils, on production variables, blood metabolites, and milk fatty acid (FA) composition of dairy cows fed a basal diet containing cactus (Opuntia stricta) cladodes and sugarcane as forages. Ten multiparous Holstein cows with 90 ± 10 d of lactation and yielding 24.2 ± 3.5 kg milk/d were assigned to dietary treatments consisting of 0, 4 (low level; LL), 8 (moderate level; ML), 12 (high level; HL), and 16% (very high level; VHL) of FFCG (DM basis) in a replicated 5 × 5 Latin square design with 21-d periods. DM intake decreased linearly from 18.9 to 16.4 kg/d, whereas a quadratic response was observed for milk yield, which increased 1.7 kg/d from control to ML, and decreased to a similar extent as FFCG further increased in the diet, resulting in a quadratic increase in gross feed efficiency (GFE). Milk protein and lactose contents were unaltered, but milk fat content gradually dropped from 3.49% to 2.23%, which was accompanied by a progressive decrease in milk fat yield and fat-corrected milk yield. Serum cholesterol levels markedly increased from 756 to 1480 mg/L, but other blood metabolites were unaltered. Except for trans-16:1 isomers, proportions of short and medium-chain FA in milk fat decreased in a linear or quadratic fashion as FFCG increased in the diet, whereas the opposite was observed for 18:0 and of 18:1/18:2 isomers, including those with conjugated double bonds. In particular, a trans-11 to trans-10 shift occurred with moderate to higher FFCG levels, resulting in a quadratic change in trans-11 18:1 and cis-9, trans-11 CLA, and a linear increase in trans-10 18:1, trans-10, cis-12 CLA and trans-9, cis-11 CLA. The n-6:n-3 ratio in milk nearly doubled with increasing FFCG, mostly due to a pronounced increase in 18:2 n-6. Proportions of odd-linear and branched-chain FA in milk fat decreased in a quadratic and linear fashion, respectively, with increasing FFCG. These results indicate that FFCG can be an effective source of PUFA for increasing rumen outflow of biohydrogenation intermediates in cows fed cactus Opuntia cladodes as a partial substitute for sugarcane. The marked milk fat depression induced by FFCG suggests that the basal diet was unable to maintain a healthy rumen environment.