Kamran Rezayazdi *1, Hassan Mehrabani Yeganeh1, Seyed Esmaeil Ghorbi1, Parham Moslehifar1, Behin Lor Kalantari1
1- University of Tehran
Abstract: (171 Views)
Introduction and Objective: The heat caused by the metabolism of nutrients and the heat of the environment are two sources of imposing heat on livestock. Heat stress in dairy cows occurs when the imposed heat load exceeds the animal's ability to eliminate it. Heat stress in lactating cows leads to a decrease in feed consumption, a reduction in milk production and the quality of milk, especially a decrease in milk fat, a decline in reproductive performance, the occurrence of various metabolic disorders such as acidosis, and endangering health and reducing the longevity of animals in the herd.Considering the annual increase in the intensity and duration of heat, as well as the high importance of the final price of milk production and the existence of financial incentives to produce more milk fat, finding suitable nutritional solutions along with management solutions to deal with heat stress as a challenge that has been for years to caused continuous and large losses to milk producers in the world and Iran, is essential. In recent years, research has been conducted regarding using additives containing medicinal plants' essential oils or effective compounds as a nutritional solution to deal with animal heat stress.This study was conducted to investigate the effect of a mix of medicinal plant essential oils including 4 families of aromatic compounds (aldehydes, monoterpene hydrocarbons, monoterpenols and phenols) as an effective additive in reducing the negative effects of heat stress on the production and composition of Holstein dairy cows' milk.
Material and Methods: To experiment, 90 Holstein dairy cows with an average milk production of 31.8±4.7 kg per day and an average lactation days of 180±20 days were divided into two experimental groups in a completely random design: 1) control and 2) medicinal plant essential oils. The experiment had two phases without treatment (initial 21 days) and the treatment days (45 days). During the main experiment, 50 grams of a 2% mixture of medicinal plant essential oils with calcium carbonate daily was provided to the second group. Temperature-humidity index (THI) was calculated daily. Milk production and composition, persistency of milk production, feed consumption and efficiency, rectal temperature, respiration rate and milk somatic cells were investigated and measured. For the statistical analysis, The MIXED procedure of SAS software version 9 was used.
Results: Although the increase in THI led to a decrease in milk production in both experimental groups, the slope of the decrease in milk production in the control group was higher than in the group that fed medicinal plant essential oils. The comparison results of the average slope of the lactation curve line, which is considered an index of persistency of milk production, showed that the medicinal plant essential oil could significantly reduce the milk production loss caused by heat stress (P<0.01). This medicinal plant essential oils led to a significant increase (3.4% on average) in daily milk production (P<0.05). Also, a significant increase in average daily milk production corrected based on 3.5% fat (3.5% FCM) from 28.83 kg to 29.81 kg (+3.40%), the average daily milk production corrected based on 4 Fat percentage (FCM 4%) from 26.66 kg to 27.58 kg (+3.45%) and energy-corrected daily milk production (ECM) from 28.91 kg to 29.86 kg (3.28%) was observed (P<0.05). medicinal plant essential oils had no significant effect on the daily dry matter intake and feed efficiency. It significantly reduced rectal temperature and breathing rate by affecting vascular dilation (P<0.05). The medicinal plant essential oils had no significant effect on the percentage of milk fat, the percentage and amount of milk protein, and the amount of urea nitrogen in milk. Also, there was no significant difference between total solids and solids without milk fat, although these traits tended to be significant (P values 0.07 and 0.09, respectively). The average amount of milk fat of the group of cows fed medicinal plant essential oils was significantly higher than the control group due to the significant increase in the amount of milk production (40 grams per day) (P<0.05). Also, the medicinal plant essential oil led to a significant decrease in the number of milk somatic cells and the score of milk somatic cells and a significant increase in the percentage of milk lactose (P<0.05).
Conclusion: According to the experiment, medicinal plant essential oils led to a significant decrease in the rectal temperature and respiratory rate of cows in heat stress (P<0.05). It also significantly increased daily milk production, 3.5% fat-corrected milk production (3.5% FCM), 4% fat-corrected milk production (4% FCM) and energy-corrected milk (ECM) ( P>0.05). Medicinal plant essential oils with no negative effect on the percentage and amount of milk protein, increased the average amount of milk fat of each cow by 40 grams per day (P<0.05). Also, the number of milk somatic cells significantly decreased and the percentage of milk lactose increased with the feed of medicinal plant extracts (P<0.05). According to the results of this research adding 50 grams of 2% medicinal plant essential oils mixture to the feed of Holstein dairy cows is an appropriate approach to improve the productive performance and health of dairy animals and economic production of milk, especially in the hot seasons.
Material and Methods: To experiment, 90 Holstein dairy cows with an average milk production of 31.8±4.7 kg per day and an average lactation days of 180±20 days were divided into two experimental groups in a completely random design: 1) control and 2) medicinal plant essential oils. The experiment had two phases without treatment (initial 21 days) and the treatment days (45 days). During the main experiment, 50 grams of a 2% mixture of medicinal plant essential oils with calcium carbonate daily was provided to the second group. Temperature-humidity index (THI) was calculated daily. Milk production and composition, persistency of milk production, feed consumption and efficiency, rectal temperature, respiration rate and milk somatic cells were investigated and measured. For the statistical analysis, The MIXED procedure of SAS software version 9 was used.
Results: Although the increase in THI led to a decrease in milk production in both experimental groups, the slope of the decrease in milk production in the control group was higher than in the group that fed medicinal plant essential oils. The comparison results of the average slope of the lactation curve line, which is considered an index of persistency of milk production, showed that the medicinal plant essential oil could significantly reduce the milk production loss caused by heat stress (P<0.01). This medicinal plant essential oils led to a significant increase (3.4% on average) in daily milk production (P<0.05). Also, a significant increase in average daily milk production corrected based on 3.5% fat (3.5% FCM) from 28.83 kg to 29.81 kg (+3.40%), the average daily milk production corrected based on 4 Fat percentage (FCM 4%) from 26.66 kg to 27.58 kg (+3.45%) and energy-corrected daily milk production (ECM) from 28.91 kg to 29.86 kg (3.28%) was observed (P<0.05). medicinal plant essential oils had no significant effect on the daily dry matter intake and feed efficiency. It significantly reduced rectal temperature and breathing rate by affecting vascular dilation (P<0.05). The medicinal plant essential oils had no significant effect on the percentage of milk fat, the percentage and amount of milk protein, and the amount of urea nitrogen in milk. Also, there was no significant difference between total solids and solids without milk fat, although these traits tended to be significant (P values 0.07 and 0.09, respectively). The average amount of milk fat of the group of cows fed medicinal plant essential oils was significantly higher than the control group due to the significant increase in the amount of milk production (40 grams per day) (P<0.05). Also, the medicinal plant essential oil led to a significant decrease in the number of milk somatic cells and the score of milk somatic cells and a significant increase in the percentage of milk lactose (P<0.05).
Conclusion: According to the experiment, medicinal plant essential oils led to a significant decrease in the rectal temperature and respiratory rate of cows in heat stress (P<0.05). It also significantly increased daily milk production, 3.5% fat-corrected milk production (3.5% FCM), 4% fat-corrected milk production (4% FCM) and energy-corrected milk (ECM) ( P>0.05). Medicinal plant essential oils with no negative effect on the percentage and amount of milk protein, increased the average amount of milk fat of each cow by 40 grams per day (P<0.05). Also, the number of milk somatic cells significantly decreased and the percentage of milk lactose increased with the feed of medicinal plant extracts (P<0.05). According to the results of this research adding 50 grams of 2% medicinal plant essential oils mixture to the feed of Holstein dairy cows is an appropriate approach to improve the productive performance and health of dairy animals and economic production of milk, especially in the hot seasons.
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