Estimation of genetic variation in A9-desaturase enzyme activity in dairy cows

The ▵9-desaturase enzyme adds a cis-9 double bond to fatty acids in adipose and mammary tissue. In the mammary gland, this reaction converts C14:0 to C14:1, C16:0 to C16:1, C18:0 to cis-9 C18:1 (oleic acid), and trans- 11 C18:1(vaccenic acid) to cis-9, trans- 11 conjugated linoleic acid (CLA). Oleic acid is of interest in human nutrition as a component of the “Mediterranean diet” and CLA has been shown to have numerous health benefits. Conversion of vaccenic acid to CLA in the mammary gland accounts for 75-80% of CLA found in milk (Lock and Garnsworthy, 2002), but activity of the Δ9-desaturase enzyme varies among individual cows irrespective of dietary manipulations (Lock and Garnsworthy, 2003), suggesting that it may have a genetic component. The objective of this study was to estimate the genetic variation in Δ9-desaturase activity in dairy cows using milk fatty acid profiles.

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Δ9 -desaturase activity in the mammary gland of lactating dairy cows

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200008371 ◽

2002 ◽

Vol 2002 ◽

pp. 181-181

Author(s):

A.L. Lock ◽

P.C. Garnsworthy

Keyword(s):

Fatty Acids ◽

Oleic Acid ◽

Mammary Gland ◽

Dairy Cows ◽

Milk Fat ◽

Desaturase Activity ◽

Unsaturated Fatty Acids ◽

Saturated Fatty Acids ◽

Lactating Dairy Cows ◽

Δ9 Desaturase

The Δ9 -desaturase system (steroyl-CoA desaturase) involves the addition of a cis double bond between carbons 9 and 10 of fatty acids. The conversion of stearic acid (C18:0) to oleic acid (cis-9 C18:1) is the predominant precursor:product of this enzyme system; conversion of saturated fatty acids (SFA) to mono-unsaturated fatty acids (MUFA) is important in determining the fluidity of milk. In previous studies (Lock & Garnsworthy 2001), we have shown that more than 50% of the oleic acid occurring in milk is produced in the mammary gland via Δ9 -desaturase. We also found that the conversion of trans-11 C18:1 to cis-9, trans-11 conjugated linoleic acid (CLA) accounted for ~80% of milk fat CLA. Increasing the activity of Δ9 -desaturase offers the opportunity of increasing the MUFA content of milk, especially oleic acid, while decreasing its SFA content, as well as increasing the CLA content of milk. Lock & Garnsworthy, (2001) also reported that there were significant differences between individual cows with regard to milk fat CLA content. In an earlier study (Lock & Garnsworthy, 2000) we found that the CLA content of milk varied throughout the year, with highest values occurring when cows received fresh pasture. In view of the significant contribution of Δ9 -desaturase to the CLA and MUFA content of milk, the objective of the work reported here was to investigate individual animal and dietary variation in Δ9 -desaturase activity in the mammary gland of lactating dairy cows.

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The effect of excess cobalt on milk fatty acid profiles and transcriptional regulation of SCD, FASN, DGAT1 and DGAT2 in the mammary gland of lactating dairy cows

Journal of Animal Physiology and Animal Nutrition ◽

10.1111/j.1439-0396.2011.01221.x ◽

2011 ◽

Vol 96 (6) ◽

pp. 1065-1073 ◽

Cited By ~ 9

Author(s):

I. J. Karlengen ◽

O. M. Harstad ◽

O. Taugbøl ◽

I. Berget ◽

A. H. Aastveit ◽

...

Keyword(s):

Transcriptional Regulation ◽

Mammary Gland ◽

Fatty Acid ◽

Dairy Cows ◽

Milk Fatty Acid ◽

Fatty Acid Profiles ◽

Lactating Dairy Cows

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The role of the mammary gland during heat stress

10.32469/10355/72201 ◽

2019 ◽

Author(s):

◽

Ricardo Oliveira Rodrigues

Keyword(s):

Blood Flow ◽

Heat Stress ◽

Mammary Gland ◽

Dairy Cows ◽

Prolonged Exposure ◽

Transcriptional Profiling ◽

Mammary Tissue ◽

Secretory Cells ◽

University Of Missouri ◽

Lactating Dairy Cows

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Disruptive effects of climate change, such as increasing environmental temperature, have direct impacts on economic viability and efficiency of food production. In lactating dairy cows, heat stress reduces milk production and alters function of mammary secretory cells, at least partly by disturbing local protein metabolism. We hypothesized that hyperthermia would not only reduce mammary blood flow but would also reduce mammary extraction of nutrients from blood. In addition, we hypothesized that transcriptional profiling of mammary tissue would reveal disruption of cellular homeostasis. Our objective was to determine the effects of hyperthermia on mammary function. More specifically, we aimed to profile mammary blood flow and the changes in mammary transcriptome of heat-stressed lactating dairy cows. We investigated the effects of early and prolonged exposure of lactating dairy cows to hyperthermia by exposing cows to programmed constantly elevated temperature and humidity to induce and maintain body temperature approximately 1[degree]C above normal. Experiments were conducted to evaluate the production responses of hyperthermic lactating dairy cows, to characterize total and nutritive mammary blood flow, and to elucidate the regulation of mammary function during early and prolonged exposure to hyperthermia. Results from these studies established that 1) hyperthermia reduces total and nutritive mammary blood flow, limiting nutrient disappearance across the mammary gland; 2) hyperthermia does not induce shunting of blood away from the gland; 3) hyperthermia affects mammary tissue transcriptome, mainly altering processes associated with ECM and cell adhesion; 4) the effects of exposure to prolonged heat stress on mammary gene expression are distinct from the effects of feed restriction, in lactating dairy cows; and 5) mammary function is reestablished within 8 days after cessation of heat stress.

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Diet Composition Affects Liver and Mammary Tissue Transcriptome in Primiparous Holstein Dairy Cows

Animals ◽

10.3390/ani10071191 ◽

2020 ◽

Vol 10 (7) ◽

pp. 1191

Author(s):

Shengtao Gao ◽

Zheng Zhou ◽

Jiaqi Wang ◽

Juan Loor ◽

Massimo Bionaz ◽

...

Keyword(s):

Mammary Gland ◽

Dairy Cows ◽

Corn Stover ◽

Functional Annotation ◽

Diet Composition ◽

Acid Metabolism ◽

Potassium Transport ◽

Corn Silage ◽

Mammary Tissue ◽

Microarray Chip

The objective of the present study was to evaluate the overall adaptations of liver and mammary tissue to a corn stover (CS) compared to a mixed forage (MF) diet in mid-lactation primiparous dairy cows. Twenty-four primiparous lactating Holstein cows were randomly allocated to 2 groups receiving either an alfalfa forage diet (MF, F:C = 60:40) with Chinese wildrye, alfalfa hay and corn silage as forage source or a corn stover forage diet (CS, F:C = 40:60). A subgroup of cows (n = 5/diet) was used for analysis of liver and mammary transcriptome using a 4 × 44K Bovine Agilent microarray chip. The results of functional annotation analysis showed that in liver CS vs. MF inhibited pathways related to lipid metabolism while induced the activity of the potassium channel. In mammary tissue, fatty acid metabolism was activated in CS vs. MF. In conclusion, the analysis of genes affected by CS vs. MF indicated mammary gland responding to lower level of linoleate from the diet (lower in CS vs. MF) by activating the associated biosynthesis metabolic pathway while the liver adaptively activated potassium transport to compensate for a lower K ingestion.

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