Effects of feeding fennel, black seed and black caraway plant on milk yield, growth hormone and prolactin in lactating Holstein cows

In recent years, the interest has been increasing in the use of medical plant in animal. Use of herbs was due to increasing in milk property. So, many researchers have been studying in this subject. Results of these researches indicated higher milk production in which supply of these drugs and their ingredients called milk enhancers or galactogogues. The increase in milk due to the use of these drugs varies depending on the type of livestock and the amount of production. Lactation is affected by nutritional and non-nutritional factors (related to endocrine, health, weather, and management) that play a role in the synthesis and secretion of milk. Chemical or herbal modifiers stimulate, maintain and increase milk production (Mortel and Mehta 2013). This study was conducted to assay the effect of galactogogues plants combination (GPC) included fennel, black seed, and black caraway powder in diet on milk production, prolactin and growth hormone levels in lactating dairy cows. A completely randomized design was used with 12 Holstein cows having 620±15 kg live weight, 30±10 days in milk, and 33±10 kg/day average milk production in a farm of Ardabil city, Iran. Cows were assigned to one of the two treatment group: 1- control (n=6) they fed basal diet based on NRC (2001) recommendation for dairy cow requirements and (2-GPC) group (n=6) fed basal diet with galactogogues plants combination powder 0.03% of body weight which consist of fennel, black seed and black caraway mixed with concentrate. The experiment continued 8 weeks after one week of adaptation period. Milk production was recorded and milk composition was measured. At the end of experiment, blood samples were taken from jugular vein of all animals and then, sent to the lab to assay prolactin and growth hormone levels. the results showed that milk production increased in animals fed herbal treatment (P<0.0001), this result is consistent with Kholif and Khorshed (2006); Abo El-Nor et al. (2007). Relative improvement in milk production may be due to its effect on livestock health (because incidence of disease cause waste of nutrients for fighting pathogens) and also may affect on acetate and succinate production of ruminal microflora, which lead to improvement in nutritional efficiency and milk production (Kholif and Khorshed 2006; Abo El-Nor et al. 2007). Milk composition percentage showed no significant change in this study, while daily produced milk composition increased significantly associated with milk production (P<0.05). These findings are in accordance with other studies (Nurdin et al. 2011; Afshar Hamidi et al. 2013). Prolactin and growth hormone levels tended to increase, but showed no significant change. A significant overnight release of prolactin hormone observed in lactating goats associated with morning and evening milking (Hart, 1974). Research on mice has also confirmed that this hormone increases by sucking milk (Sar and Meites, 1969). On the other hand, it has been reported that galactogogues compounds stimulate activity and number of alveoli, so it resulted in increasing of milk secretion (Ravikumaretal., 2008). In the study of Salahshoor et al. (2012), intraperitoneal injection of alcoholic extract of nettle in doses of 25, 50, and 100 mg/kg for 21 days in female rats, significantly increased the number of alveoli. However, the increase in the amount of prolactin hormone and alveolar diameter were not significant. They concluded that the effect of nettle on the increase of milk could be due to the supply of essential nutrients that the mother received from the plant and does not related to the effect of produced prolactin hormone. Turkyilmaz et al. (2011) suggested that the effect of herbal galactogogues can be attributed to their phytoestrogenic activity. These molecules may be similar to 17-estradiol which is an endogenous estrogen and stimulates the proliferation of the epithelial cells of the breast. Therefore, based on the results of previous studies, this ineffectiveness can be considered in the amount of compound used, the type and condition of livestock and the method of application such as extract or leaves, or in the oral or injection form, duration of using and may be because of other factors. So, more studies are needed to find more accurate results. Based on the present results, it was concluded that using galactogogues plants combination improved milk production in cows, while composition of milk yield showed no significant difference. Dosage of plant powder in this study did not affect growth hormone and prolactin.