Final report for GNE19-202
Project Information
The acylated form of ghrelin (AG) reportedly inhibits heat production by modulating feed intake and thermogenesis. Octanoic acid (OA) is the primary substrate of the ghrelin acylation process. The objective of the current study was to investigate the impact of dietary OA supplementation on lactating cows’ performance, ghrelin concentration, and rectal temperature during mild heat stress. Eight multiparous lactating Holstein cows were assigned to treatments in a 2 x 2 Latin square design with a 14-d trial period, which included a 7-d adaption period and 7-d data collection period. Dietary treatments were basal diet (BD) or BD plus a top dress of 600 ml /cow/day OA (BDOA). Cows were fed once daily at 0800 h at approximately 110% of expected DMI. Rectal temperature was recorded at 0800 h (RT1) and 1600 h (RT2) daily, 24 h area under the curve for rectal temperature (RTAUC) was calculated. Milk yields were recorded daily, milk and blood samples were collected on days 6 and 7 of each data collection period for the determination of milk components and AG. A log transformation was applied for analyses of AG (LAG). The average daily minimum, average, and maximum THI during the experiment were 68, 74, and 78, respectively, which was above the heat stress threshold for lactating cows (72 daily average THI). A series of repeated measures analyses of LAG, RT1, RT2, DMI, milk yield, and milk components were used to determine the effects of BDOA, THI, and their interaction. The repeated effect was test day with the subject of cow and significance was declared at P ≤ 0.05 and tendencies at P ≤ 0.10. Compared to BD, BDOA decreased DMI (18.1 vs. 21.4 kg, P = 0.05), somatic cell score (2.09 vs. 2.65, P < 0.01), milk urea nitrogen (11.0 vs. 12.9 mg/dl, P < 0.01), RTAUC (938.05 vs. 940.59 °C * h, P < 0.05), and tended to decrease RT2 (39.33 vs. 39.48 °C, P < 0.1). Octanoic acid did not alter milk yield (33.6 for OA vs. 33.5 kg), milk fat (4.05 vs. 4.25 %), milk protein (2.88 vs. 2.90 %), or LAG (3.92 vs. 4.01 loge pg/ml). There was a BDOA by THI interaction for RT2 and RTAUC, with the slope larger for BD than BDOA, indicating BDOA helped to maintain body temperature as THI got higher within the range of our experiment. Our data demonstrated that dietary supplementation of OA may have a mitigating effect of heat stress but not through stimulating ghrelin acylation.
The objective of the current experiment was to investigate the impact of dietary OA supplementation on lactating cows’ performance, AG, and rectal temperature during mild heat stress.
Heat stress is a challenge to cow welfare and profitability to dairy farmers worldwide. The main contributors for heat stress related economic losses are reduced milk production, impaired reproduction, increased health related problems, and increased culling rate (St-Pierre et al., 2003). The negative impact of heat stress on dairy cows is a growing problem because of the extra metabolic heat produced with the increased milk production and the unfavorable genetic relationship between selecting for milk production and heat stress (Aguilar et al., 2010).
Reduced DMI is a well-known symptom of heat stress, adding extra fatty acid (FA) in the diet is a common practice during heat stressed periods (Drackley et al., 2003). The benefit of FA supplementation during heat stress are two folds. Firstly, FA has a high caloric value that increases the energy density of the diet to maintain the energy intake of a cow during heat stress even though DMI decreased. Secondly, the efficiency of FA digestion and absorption can be as high as 0.97 (Baldwin et al., 1985) which means on the same energy basis, the metabolism of FA generates less heat than other dietary energy sources such as fiber or starch. The majority of the previous researchers were focusing on long-chain FA (LCFA; 14 or more carbon atoms), including saturated LCFA (Drackley et al., 2003; Bradford et al., 2008) and unsaturated LCFA (Bauman and Griinari, 2001; Palmquist et al., 2005). Octanoic acid (OA) is a medium-chain FA (MCFA; 7 to 12 carbon atoms). The difference in chain length between LCFA and OA determined that they are metabolized differently post-absorption. Unlike LCFA, OA doesn’t need to be packaged into chylomicrons to be transported and utilized, instead, the majority of MCFA enters the portal vein and binds to albumin, then goes directly to the liver where they will be oxidized (Schönfeld and Wojtczak, 2016). Due to metabolism differences, the biological functions of OA need to be studied separated from LCFA, but it is still largely uninvestigated.
Ghrelin is a gut derived peptide hormone (Kojima et al., 1999). It has been reported that the acylated form of ghrelin (AG) can suppress brown adipose tissue activity (Mano-Otagiri et al., 2009), decrease heat production and body temperature in mice (Lin et al., 2011) and human (Wiedmer et al., 2011). Ingestion of MCFA, especially OA was reported to increase AG concentration in mice (Nishi et al., 2005) and cows (Fukumori et al., 2013). But the effects of dietary supplementation of OA on lactating cows during heat stress period has not been studied. We hypothesized that supplement lactating cows with OA during mild heat stress can increase plasma AG, and decrease rectal temperature.
Research
Experimental design and treatments
The experiment was reviewed and approved by the Institutional Animal Care and Use Committee at the University of the Pennsylvania State University (protocol no. 201901072). Eight multiparous Holstein cows were grouped by days in milk (DIM) and body weight (BW) (3.27 ± 1.50 parity; 202 ± 36 DIM; 702 ± 84 kg initial BW) were assigned to treatments in a Latin square design with a 14-d trial period, which included a 7-d adaption period and 7-d data collection period. The experiment was conducted at the Penn State University Dairy Production Research and Teaching Center.
Cows were fed once daily at 0800 h at approximately 110% of expected dry matter intake (DMI), refusals were measured daily during the data collection period of each trial period. Treatments were basal diet (BD; Table1) or BD plus a top dress of 600 ml (546 g) /cow/day OA (BDOA; Food grade octanoic acid, product NO. w279900, Sigma-Aldrich, St. Louis, MO). The basal diet was mixed in a Kuhn RC 250 mixer. Octanoic acid used in this experiment has a purity of 99.6%, a boiling point of 237 ℃, a melting point of 15 – 17 ℃, a density of 0.91 g/ml at 25 ℃, and ME of 7.28 Mcal/kg (calculated according to NRC, 2001). Fresh feed samples of BD were collected at the beginning of each treatment period for nutrient composition analysis. The nutrient composition of BD was analyzed by Near-Infrared Reflectance spectroscopy procedures (Table 2; Cumberland Valley Analytical Services Inc., Maugansville, MD). Actual ME intake (MEI) and total fat intake (TFI) of BD and BDOA were calculated based on DMI, and nutrient composition of the diet.
Environmental measurements
The internal ambient temperature (AT, ℃) and relative humidity (RH, %) were monitored and recorded hourly by a data logging hygrometer (Fisherbrand, Cat. No. 15-079-679). Temperature humidity index (THI) was calculated with the formula:
THI = (9/5 * AT + 32) - (11/20 - 11/20 * RH) * (9/5 * AT - 26) (NOAA, 1976; Ravagnolo and Misztal, 2000). Across the experiment, the average daily minimum, average, and maximum THI were 68, 74, and 78 respectively (Table 3).
Experimental Protocol
Rectal temperature measurements. Rectal temperatures (RT) were measured twice daily at 0800 h (RT1) and 1600 h (RT2) with a digital thermometer. The 24 h area under the curve of RT (RTAUC) was calculated based on RT1, RT2, and RT at 0800 h of the day following the test day (24 h after RT1, RT3) according to the formula: RTAUC = (RT1 + RT2) * 8 h /2 + (RT2 + RT3) * 16 h /2.
Milk Sampling. Cows were milked twice daily at 0700 and 1900 h, milk yield (MY) was determined by an integrated milk meter (AfiMilk; SAE Afikim, Israel). Milk samples were collected at each milking on days 6 and 7 of each data collection period (4 milk samples per cow per period). Milk samples were sent to the local Dairy Herd Improvement Association laboratory (Dairy One DHIA, Ithaca, NY) to quantify milk fat, protein, lactose, somatic cell count (SCC), and milk urea nitrogen (MUN) with infrared spectroscopy and Milkoscan models 6000, or 7 and Fossomatic models 5000/FC (Foss Electric A/S, Hillerød, Denmark).
Blood Sampling. Blood samples were collected from the tail vein on days 6 and 7 of each treatment period at 1600 h to determine plasma AG. Blood samples were collected into tubes containing ethylenediaminetetraacetic acid (BD Vacutainer, Franklin Lakes, NJ) and then placed on ice. Within 15 minutes of the last sample collection each day, blood was centrifuged at 2000 x g for 15 minutes. Plasma samples were treated with 50 μL of 1 N HCl and 10 μL of phenylmethylsulfonyl fluoride (PMSF) per mL of plasma for AG analysis by radioimmunoassay. All plasma samples were then frozen and stored at -20 ℃.
Plasma analyses. Plasma AG was quantified by a commercial radioimmunoassay kit (Cat. No. GHRA-88HK, Millipore Inc., Billerica, MA). This kit was specific for human AG analysis but was validated for bovine plasma by Deaver et al. (2013). The intraassay coefficient of variability over 3 assays was 4.96%, and the average interassay coefficient of variability was 5.8%.
Data edits
Initial analysis of data showed a positively skewed distribution for AG, so a natural logarithm transformation was used to normalize the distribution of AG. The Shapiro-Wilk test indicated a normal distribution for log-transformed AG (LAG). During the experiment period, two cows suffered injuries that caused sudden, short-term DMI decline at days 12 and 26, respectively. We decided to remove their records for 3 days (the day of the injury and two following days).
Statistical Analysis
The MIXED procedure of SAS (version 9.4, SAS Institute Inc., Cary, NC) was used to perform analyses. Analyses of milk compositions were conducted using a repeated measures approach. The initial model included the fixed effects of treatment, time of day (TOD), period, a covariate of THI, and the interaction between treatment, TOD, and THI. The interaction was eliminated if insignificant as were TOD or THI when not significant. The repeated variable was TOD within the test day with cow as the subject. Results are reported as LSM and standard error of treatment.
Analysis of DMI, MY, LAG, and RT were also conducted with a repeated measures approach. The model included the effects of treatment, period, a covariate of THI, and the interaction between treatment and THI. The interaction term was eliminated if insignificant. Test day was the repeated variable and cow was the subject.
In addition to testing effects of average, minimum, and maximum THI of the test day, effects of these measurements from 1 and 2 d before the test day were also tested against DMI, MY, and RT. The purpose of this step was to reveal any potential lag effect of heat stress as reported by West et al., (2003), Spiers et al., (2004), and Bernabucci et al., (2014). The most appropriate covariate to analyze a certain dependent variable was determined based on the lowest Akaike information criterion with correction (AICC).
The compound symmetry, spatial power, and autoregressive 1 covariance structures were tested for every analysis above and the model that had the lowest AICC was selected. The Kenwood Rogers method was used to adjust the denominator degrees of freedom. Results are reported as least-squares means (LSM) and standard error of the treatment. Differences were declared significant at P ≤ 0.05 and tendencies at 0.05 < P ≤ 0.10.
DMI, milk yield, milk composition, and active ghrelin
Cows fed BDOA diet had lower DMI (18.1 kg/d; Table 4) compared to cows that fed BD diet (21.4 kg/d, P = 0.05). Metabolizable energy intake did not differ between BD and BDOA (60.2 vs. 54.9 Mcal/d for BD and BDOA, respectively; P > 0.1). Total fat intake was higher for BDOA than BD (+0.36 kg/d, P < 0.01). Previous research on dietary OA supplementation is limited. But when cows were fed a mixture of MCFA containing 65 % OA at 500 ml/d, their DMI decreased (Grummer and Socha, 1989). When fed a mixture of MCFA containing 25% OA as calcium salt at 1.5% of diet DM, cows had decreased DMI as well (Fukumori et al., 2013). Bradford et al., (2008) observed an elevated level of cholecystokinin in cows supplemented with saturated LCFA which can cause satiety (Beglinger and Degen, 2004). But McLaughlin et al., (1998) reported that, unlike LCFA, FA with less than ten carbon atoms did not stimulate cholecystokinin secretion. So, the declined DMI for BDOA was unlikely caused by elevated cholecystokinin concentration. On the other hand, declined DMI for BDOA may associate with the impact of OA on rumen fermentation (Ajisaka et al., 2002; Dohme et al., 2008) since post-ruminally infused MCFA did not affect DMI (Rico et al., 2020). It has been shown that MCFA, especially OA can decrease the number of protozoa in the rumen fluid (Ajisaka et al., 2002; Dohme et al., 2008) and decrease fiber digestibility (Dohme et al., 2008).
Milk yield and concentration of fat, protein, and lactose were not affected by OA, Gross feed efficiency of BDOA (1.83) was higher than BD (1.59, P < 0.01; Table 5), The effects of dietary OA or MCFA on milk yield and composition in the literature were inconsistent. Grummer and Socha, (1989) observed no change in milk yield, milk fat, and protein concentration when supplemented with a mixture of MCFA containing 65 % OA. Van Zijderveld et al., (2011) reported a mixture of MCFA containing OA supplementation increased milk fat concentration but did not alter milk yield and milk protein concentration. While Fukumori et al., (2013) found MCFA treatment decreased protein and lactose concentration, showed a tendency of decreased MY, but did not affect milk fat concentration.
The somatic cell score of BDOA (2.09) was lower than BD (2.65, P < 0.01). It has been shown that OA has antimicrobial properties including antialgal (McGrattan et al., 1976), antibacterial (Feldlaufer et al., 1993), and antiviral (Thormar et al., 1987) functions. Adding 50 mM or 100 mM OA in the milk culture reduced bacterial counts of major mastitis pathogen such as Strep. agalactiae, Strep. dysgalactiae, Strep.uberis, Staph. aureus, and E. coli (Nair et al., 2005). The literature on the relationship between OA and milk SCS is limited but the potential of OA being viable mastitis and SCS management tool needs further investigation.
Log transformed AG did not differ between BD (4.01 loge pg/ml) and BDOA (3.92 loge pg/ml, P > 0.1). Ingestion of OA was shown to increase LAG in rats (Nishi et al., 2005) and cows (Fukumori et al., 2013) but Lemarié et al., (2015) observed no difference in AG between control rats and OA supplemented rats. We didn’t observe any AG difference between treatments, time of blood sampling may be a factor. We took blood samples in the afternoon, 8 h after morning feeding to mitigate the impact of preprandial AG surge (Sugino et al., 2002; Field et al., 2013). The nature of OA (8 carbon FA) determined that it will be transported to the liver for oxidation through the portal vein directly without incorporated into chylomicrons like LCFA (Schönfeld and Wojtczak, 2016). So, it’s possible by the time we took the blood sample, most OA supplements had already been oxidized, thus the difference in LAG was too trivial to be detected between BD and BDOA.
Table 5 presented the change in DMI, MEI, TFI, MY, and GFE per unit change in the correspondent THI measurement. Based on AICC, the most impactful THI measurement for DMI, MEI, and TFI was the average THI of 2 d before test day. Within the range of THI records of our experiment, for every unit of THI increase, DMI decreased 0.49 kg/d (P < 0.01), TFI decreased 0.03 kg/d (P < 0.01), and MEI decreased 1.39 Mcal/d (P < 0.01). The most impactful THI measurement for MY and GFE was the average THI of 1 day before test day. Gross feed efficiency decreased 0.03 kg/kg (P < 0.01) and MY tended to decrease 0.46 kg/d (P < 0.1) for every unit of THI increase within the range of our experiment. It has been reported that the impact of heat stress on DMI and MY might have a 2 – 4 d lag period, which means the climatic condition of 2 – 4 d before the test day has a bigger impact on DMI and MY than the climatic condition of the test day (West et al., 2003; Spiers et al., 2004; Bernabucci et al., 2014). Our study showed that daily average THI of 2 d before the test day was the most appropriate THI measurement on DMI which agrees with Spiers et al., (2004). The most appropriate climatic variable for MY was inconsistent in the literature. Collier et al., (1981) observed ambient temperature of 24 – 48 h before the test day had the biggest impact which is aligned with our observation. West et al., (2003) reported that THI of 2 d before the test day had the most negative impact on MY whereas Bernabucci et al., (2014) reported THI of 3 - 4 d before the test day was the most significant variable on MY.
Rectal temperature
The rectal temperature at 0800 h did not differ between treatment groups while OA treatment tended to decrease RT2 (-0.15 ℃, P < 0.1, Table 6). 24 h area under the curve of RT was lower for the BDOA (938.05 ℃*h) than BD (940.59 ℃*h, P <0.05). The most impactful THI measurement for RT was the mean THI of the test day. Higher THI was associated with higher RT1, RT2, and RTAUC. A treatment by THI interaction was observed for RT2 (P = 0.05) and RTAUC (P < 0.05). Within the range of our experiment, for every unit THI increases, RT2 increased 0.16 ℃ for BD and 0.10 ℃ for BDOA. 24 h area under the curve for RT increased 2.48 ℃*h for BD and 1.28 ℃*h for BDOA. No treatment effect was detected for RT1. Chan et al., (1997) reported adding 3% LCFA in the basal diet did not affect DMI or RT, whereas Wang et al., (2010) observed a lower RT in the afternoon for cows supplemented with 3% saturated LCFA, but LCFA supplementation did not alter DMI. Declined DMI could be one explanation for the lower RT2 in our experiment. For cows that had similar body weight, DMI is the most important factor that affects heat production (Morris et al., 2020). At the same time, the efficiency of FA digestion and absorption can be as high as 0.97 (Baldwin et al., 1985). As a result, when cows had similar energy intake, BDOA would generate less heat during digestion and absorption than BD. More studies are still needed to determine if OA had a direct impact on thermogenesis other than decreased DMI and metabolic heat production.
Table 1. Ingredient of the basal diet.
|
Ingredient, % of DM |
|
|
Corn silage |
36.6 |
|
Alfalfa haylage |
11.9 |
|
Grass hay |
11.9 |
|
Ground corn |
10.3 |
|
Canola meal |
7.95 |
|
Chocolate byproduct |
6.36 |
|
Heated whole soybean |
4.77 |
|
Calcium soap |
4.37 |
|
Whole cottonseed |
2.39 |
|
Calcium carbonate |
1.21 |
|
Sodium monophosphate |
1.00 |
|
Salt |
0.50 |
|
Vitamin premix1 |
0.40 |
|
Molasses |
0.20 |
|
NPN2 |
0.10 |
1Contained (%, as-fed basis): 46.7 dry corn distillers grains with solubles; 37.2 limestone; 8.0 magnesium oxide; 6.4 salt; 0.86 trace mineral premix; 0.48 vitamin ADE premix; and 0.07 selenium premix.
2Nonprotein nitrogen fed as slow-release urea (259% CP, DM basis; Optigen, Alltech Inc., Lexington, KY).
Table 2. Nutrient composition of the basal diet.
|
Nutrient composition, % of DM |
|
|
DM |
46.9 |
|
CP |
16.1 |
|
NDF |
34.9 |
|
ADF |
22.8 |
|
Starch |
20.6 |
|
Crude fat |
5.96 |
|
TDN |
72.9 |
|
NEL, Mcal/kg of DM |
1.92 |
|
ME, Mcal/kg of DM |
3.21 |
Table 2. Basic statistics of daily minimum, mean, and maximum temperature humidity index (THI) during the experiment.
|
THI |
Mean |
SD |
Range |
|
Minimum |
68 |
4.45 |
57 - 74 |
|
Mean |
74 |
2.02 |
69 - 77 |
|
Maximum |
78 |
2.44 |
73 - 83 |
Table 3. Least squares means (± SE) of dry matter intake, ME intake (MEI), and total fat intake (TFI) of cows fed basal diet (BD) or octanoic acid treatment diet (BDOA).
|
BD |
BDOA |
P - value |
|
|
DMI, kg/d |
21.4 ± 1.5 |
18.1 ± 1.5 |
0.05 |
|
MEI, Mcal/d |
60.2 ± 4.2 |
54.9 ± 4.3 |
0.26 |
|
TFI, kg/d |
1.26 ± 0.89 |
1.62 ± 0.90 |
<0.01 |
Table 4. Least squares means (± SE) of milk yield (MY), milk composition, gross feed efficiency (GFE) and log transformed acylated ghrelin concentration (LAG) of cows fed basal diet (BD) or octanoic acid treatment diet (BDOA).
|
BD |
BDOA |
P - value |
|
|
MY, kg |
33.5 ± 2.6 |
33.6 ± 2.6 |
0.97 |
|
Fat, % |
4.25 ± 0.22 |
4.05 ± 0.25 |
0.38 |
|
Protein, % |
2.90 ± 0.07 |
2.88 ± 0.07 |
0.35 |
|
Lactose, % |
4.75 ± 0.06 |
4.77 ± 0.06 |
0.42 |
|
SCS |
2.65 ± 0.52 |
2.09 ± 0.53 |
<0.01 |
|
MUN, mg/dl |
12.9 ± 1.1 |
11.0 ± 1.1 |
<0.01 |
|
GFE1 |
1.59 ± 0.05 |
1.83 ± 0.05 |
<0.01 |
|
LAG, loge pg/ml |
4.01 ± 0.09 |
3.92 ± 0.11 |
0.53 |
1 GFE = MY/DMI.
Table 5. Changes (± SE) in DMI, ME intake (MEI), total fat intake (TFI), milk yield (MY), and gross feed efficiency (GFE) per one unit increase of THI.
|
Variables |
Slope |
P - value |
|
DMI1, kg/d |
-0.49 ± 0.15 |
<0.01 |
|
MEI. Mcal/d |
-1.39 ± 0.44 |
<0.01 |
|
TFI, kg/d |
-0.03 ± 0.01 |
<0.01 |
|
MY2, kg/d |
-0.46 ± 0.27 |
0.09 |
|
GFE3 |
-0.03 ± 0.02 |
0.04 |
1 Dry matter intake, MEI, TFI were regressed on the daily average THI of 2 days before the test day.
2 Milk yield and GFE were regressed on the daily average THI of 1 day before the test day.
3 GFE = MY/DMI.
Table 6. Least squares means (± SE) and changes (± SE) per one unit increase of THI of rectal temperature at 0800 h (RT1), 1600 h (RT2), and 24 h area under the curve for rectal temperature (RTAUC) of cows fed basal diet (BD) or octanoic acid treatment diet (BDOA).
|
RT1, ℃ |
RT2, ℃ |
RTAUC1, ℃*h |
|
|
BD |
38.93 ± 0.10 |
39.48 ± 0.10 |
940.59 ± 2.37 |
|
BDOA |
38.87 ± 0.11 |
39.33 ± 0.11 |
938.05 ± 2.42 |
|
|
|
|
|
|
Slope2 |
|
|
|
|
BD |
0.09 ± 0.03 |
0.16 ± 0.03 |
2.48 ± 0.55 |
|
BDOA |
0.07 ± 0.02 |
0.10 ± 0.02 |
1.28 ± 0.41 |
|
|
|
|
|
|
P - value |
|
|
|
|
Treatment |
0.46 |
0.06 |
0.04 |
|
THI |
<0.01 |
<0.01 |
<0.01 |
|
Treatment * THI |
0.44 |
0.05 |
0.03 |
1 RTAUC was calculated based on RT1, RT2, and RT at 0800 h of the day after the test day (24 h after RT1; RT3) according to formula: RTAUC = (RT1 + RT2) * 8 h /2 + (RT2 + RT3) * 16 h /2.
2 RT1, RT2, and RTAUC were regressed on the daily average THI of the test day.
In conclusion, dietary supplementation of OA at the level investigated decreased lactating cows DMI but not energy intake. Milk yield, milk fat, protein, and lactose concentration were not altered by feeding OA. Decreased somatic cell score was observed during OA feeding. Cows had a lower rectal temperature at 1600 h when fed OA at the investigated level, but no difference was found in plasma ghrelin concentration at 1600 h between treatment and control. The decreased RT of BODA may be due to less DMI, higher metabolism efficiency of OA, or a combination of the two. Our experiment demonstrated that dietary supplementation of OA decreases DMI and RT; OA did not alter milk production and ghrelin concentration. We cannot confirm the hypothesis that OA decreases cows' RT through ghrelin.
The authors gratefully acknowledge the staff of the Penn State University Dairy Teaching and Research Center for their assistance in managing the cows. Funding for the project was provided by the National Institute of Food and Agriculture, U.S. Department of Agriculture, through the Northeast Sustainable Agriculture Research and Education program under subaward number GNE19-202.
Education & Outreach Activities and Participation Summary
Participation Summary:
Had several discussions with farmers and other faculties in the Ag science department.
Project Outcomes
Based on our experiment, it is not feasible to use pure octanoic acid as a routine dietary supplement for dairy cows due to its high price. But there are still two potential ways to utilize its benefit:
- Use it as mastitis and somatic cell score control tool, especially for organic farmers that cannot use antibiotic treatment on mastitis cows.
- If people can produce octanoic acid at a cheaper price, it would be really helpful for cows in the transition period that is facing a negative energy balance. Octanoic acid can be used to promote positive energy balance.
Mastitis related costs for a lactating cow can be as high as 600 dollar per cow per year. Using octanoic acid therapeutically for a 7 day treatment costs about 7 dollars (1 dollar a day). We observed a 20% reduction in somatic cell score in milk. If that con translate to a 20% reduction in the mastitis related cost, the total saving for the farmers could be 600 * 0.2 - 7 = 113 dollar per cow per year. Considering the US has a dairy cow population of 9 million, the total potential saving for the dairy industry could be as high as 1 billion dollars!
- The literature on the relationship between OA and milk SCS is limited but the potential of OA being viable mastitis and SCS management tool needs further investigation.
- The impact of dietary octanoic acid on cows' ghrelin concentration needs more investigation with more blood samples taken during the feeding period.