Accessing drop in milk production in cattle due to cold climate and subsequent nutrient amelioration in temperate Kashmir

Low ambient temperature is typical in temperate Kashmir where the temperature during winter season ranges from -5 to 10°C. Factors that create stress during the winter season in temperate regions are cold, wind, snow and rain. The primary effect on livestock is due to temperature. All these factors alter the maintenance energy requirement of livestock. All mammals are warm blooded and need to maintain a constant core body temperature. Animals experience cold stress when the temperature falls, below the lower limit of thermoneutral zone, called the “lower critical temperature”. Increase in metabolic activity of body to generate more heat, is the first reaction of body to combat the effects of cold stress. When environmental temperature decreases below the thermal comfort level, heat loss must equal endogenous heat production (thermogenesis) in order to achieve homeostasis, i.e. maintenance of body temperature in a stable thermo neutral range (Lenis Sanin et al., 2015). Cold stress activates several physiological responses.
        
Following the exposure of a lactating dairy cows to a continuous low environmental temperature, over-compensating physiological adjustments lead to a marked decline in milk production. Subsequently, the animal may become acclimated or exhausted, depending on the level of milk production, its adaptability to cold stress, or other factors (Johnson and Vanjonack, 1976).
        
Reduced productivity may be a consequence of the diversion of energy from productive functions to maintenance (Broucek et al., 1991). Further the absence of green fodder may also compromise milk production in dairy cattle during winter season. Cold climate not only affects productive capacity of animals but has also impact on underlying endocrine parameters that are necessary for survival of  animals.
        
Galactogogues are synthetic or plants molecules used to induce, maintain, and increase milk production (Mortel and Mehta, 2013). Galactogogues, both synthetics and herbal, have been poorly studied in veterinary medicine. Fenugreek (Trigonella foenum-gracum L.) seeds, known as ‘Methi’ seeds in Hindi, are aromatic, and considered as a carminative tonic and galactagouge. Besides providing the flavor to mask the unpala table feed ingredients, they act as emollient for inflammation of the intestinal tract. Therefore, these seeds form the constituent of a condition powder for cattle, horses and sheep and also used to render musky hay and compressed fodder palatable (Anonymous, 1976). Abo El-Nor (1999) fed fenugreek seeds to buffaloes and reported improved feed efficiency, milk yield and economic efficiency. However, there are scanty information about the effect of fenugreek supplementation on feed intake and nutrient digestibility in dairy animals.
        
The objective of the present study was to evaluate the effect of sustained exposure to cold climate on the milk production and endocrine responses in dairy cattle in temperate Kashmir.

The present study was conducted at Mountain Livestock Research Institute (MLRI), SKUAST-Kashmir and in various dairy farms in the vicinity where the temperature in the winter months ranges from -4 to 10°C. In the treatment group, the animals were provided with 150 grams of jaggery and 200 grams of crushed fenugreek daily in addition to normal feeding schedule (NRC, 2001). The data regarding milk yield and associated parameters were compared between winter (December to February) and spring (March to May) months. The milk yield was recorded daily for 15 days and then presented as an average.
        
Blood samples (10 ml) were collected in sterile heparinized vacutainer (BD Vacutainer^TM, UK) tubes from jugular vein puncture, posing minimum disturbance to animal, from the days 0-165 postpartum at 15 days interval with respect to day of parturition. Samples were brought to the laboratory in chilled iceboxes soon after collection and centrifuged at 1200×g at 4°C for 20 minutes to separate the plasma. The plasma samples were analyzed for hormones (Prolactin, Cortisol, GH, and TSH) and blood glucose. Hormones and blood glucose were measured by ELISA reader (Multiscan EX, Cat. no. 1507300) using standard kits from calbiotech. Milk composition was measured by milk analyser (Ekomilk, Ultra PRO).
 
Statistical analysis
 
Data were analysed using two-way ANOVA with SPSS package programme (SPSS 9.00 software for Windows, SPSS Inc., Chicago, IL) as per Snedecor and Cochran (1994).

The data regarding milk yield of cows is given in Table 1. Milk yield of cows under treatment group (6.41±0.53 kg/day) varied significantly (p<0.05) from control group (4.48±0.21 kg/day) of animals during winter months. In spring although milk yield was higher in treatment group (9.12±0.22) as compared to control (8.68±0.23 kg/day) but the difference was nonsignificant. Similarly overall milk yield was significantly (p<0.05) higher in treatment group (7.76±0.49 kg/day) as compared to control (6.58±0.39 kg/day). Milk yield was significantly (p<0.05) higher during spring as compared to winter months in both treatment (9.12±0.22 and 6.41±0.53 kg/day) and control (8.68±0.23 and 4.48±0.21 kg/day) groups of animals.
 

        
The decrease in milk production in the present study was supported by (Broucek et al., 1991) showing similar changes in milk drop in cold climate. Young (1981) also observed that in lactating cows, low ambient temperatures reduce milk yield, an effect most marked during the early stages of lactation. Lower milk production in cold climate was also observed by Angrecka and Herbut (2015) in dairy cattle. Persistent cold climate may lead to thermoregulation impairments, cold stress, and lower milk production accompanied by increased feed intake. Reduced productivity may result because of the diversion of energy from productive functions to maintenance. In addition there may be a direct thermal effect on the mammary tissue (Christopherson and Young, 1986), thus reducing the blood flow to the udder (Johnson, 1987).
        
Fenugreek has been shown to have a positive effect on lactation performance in ruminants such as dairy cows, water buffaloes and dairy goats (El-Alamy et al., 2001). In goats, it has been reported that feeding with 10 g daily of fenugreek seed increases milk production (Kholif and El-Gawad, 2001). It is well known that adding natural feed additives to the diet of dairy animals such as dairy goats has a positive effect on milk production as reported by El-Abid and Nikhaila (2010). Alamer and Basiouni (2005) also observed beneficial effects of fenugreek on milk yield and reported that the usage of fenugreek in the diet of dairy goats resulted in a definite increase in milk yield compared to the control group. Jaggery helps in increasing milk production and is also useful in increasing milk let down in dairy cattle (Senthilkumar et al., 2016), supporting thus present study were inclusion of Jaggery in winter has increased milk production in cattle. Jaggery is the instant source of energy and is possibly for the maintenance in cold climate thus sparing glucose for higher milk production.
        
Glucose level (Table 2) was significantly (p<0.05) lower in treatment group (50.68±1.46 mg/dl) as compared to control group (59.65±0.38 mg/dl) of animals in winter. However the difference in glucose levels during spring months was nonsignificant in both control (51.01±0.23 mg/dl) and treatment (51.00±0.17 mg/dl) group of animals. Again overall glucose level was a significantly (p<0.05) higher in control (55.33±1.32 mg/dl) as compared to treatment (50.84±0.70 mg/dl) group of animals.
 

        
Similar to present findings Broucek et al., (1991) also observed increased glucose levels in cold climate in cows. Shijimaya et al., (1985) observed increased levels of glucose under cold conditions in Holstein-Friesian cows. Girardier and Stock (1983) observed mobilization of glucose from the glycogen stores in the liver and by hepatic gluconeogenesis in the cold climate increasing thus glucose levels in the blood. The sparing of glucose in the blood is utilized for maintenance and survival in the cold climate thus compromising productive capacity of animals. Weekes et al., (1983) showed that plasma glucose concentration and basal glucose flux were elevated in adult sheep exposed to 0°C, probably as a result of higher glucagon concentrations.
        
The difference in cortisol (Table 3) was significantly (p<0.05) lower in treatment group (24.33±1.84 ng/ml) in comparison to control (33.04±0.27 ng/ml) during winter while the difference was nonsignificant in spring in both control (15.63±0.48 ng/ml) and treatment (13.90±0.38 ng/ml) group of animals.
 

        
The present study found the highest cortisol concentrations in winter, in agreement with the findings of other authors (Titto et al., 2013). Frank et al., (2003) observed increased baseline concentrations of the stress-related hormones ACTH and cortisol in response to brief exposure (i.e., 5 d) of pigs to cold. The main function of cortisol is to mobilize energy reserves to promote increased blood glucose levels by stimulating hepatic gluconeogenesis and reducing cellular glucose uptake.
        
Growth hormone (Table 4) was significantly (p<0.05) higher in treatment group (5.53±0.16 ng/ml) in comparison to control (3.34±0.16 ng/ml) during winter but in spring the difference was nonsignificant in control (6.13±0.12 ng/ml) and treatment (6.56±0.11 ng/ml) group of animals. Overall mean of GH was significantly (p<0.05) higher in treatment group (6.04±0.18 ng/ml) in comparison to control (4.73±0.43 ng/ml) group of animals.
 

        
Similar to present study Olsen and Trenkle (1973) has shown that growth hormone increases in cows during cold exposure. Milk production is influenced by a lot of factors and mechanisms which is regulated by endocrine processes and hormones such as GH (Boutinaud et al., 2003). GH is therefore important in milk production and mammary growth in order for ruminant lactation to take place (Accorsi et al., 2002). It is suggested that plasma growth hormone in buffaloes could be candidate in mediating fenugreek action in increasing milk production (Tomar et al., 1996). Diocin is a natural saponin found in Fenugreek and has a structural similarity to oestrogen, which leads to an increased release of growth hormone (GH) by binding to the receptors on pituitary cells. This, in turn, results in an increase in milk secretion (Graham et al., 2008).
        
The prolactin levels (Table 5) were significantly (p<0.05) higher in treatment group (7.20±0.38 ng/ml) in comparison to control (5.67±0.13 ng/ml) during winter but in spring the difference was nonsignificant in control (10.45±0.15 ng/ml) and treatment (11.04±0.07 ng/ml) group of animals. The overall prolactin level was nonsignificantly higher in treatment (9.12±0.61 ng/ml) as compared to control (8.06±0.72 ng/ml) group of animals.
 
  
 
Abo El-Nor (1999) reported that feeding lactating buffaloes with fenugreek increased prolactin hormone, which is considered one of the major hormones for milk synthesis and secretion. In goats feeding with fenugreek increased milk production and this effect might be mediated via PRL stimulation, because PRL concentrations were found to be significantly higher in the fenugreek fed goats (Janabi, 2012) in the similar way as in present study. Hormones such as GH and prolactin play an important role in regulating mammary function in ruminants (Flint and Knight, 1997) and are important in regulating nutrients to the udder. GH has lipolytic and diabetogenic (Svennersten-Sjaunja and Olsson, 2005) properties thus increasing blood flow to the udder for higher milk synthesis.
        
TSH (Table 6) was nonsignificantly higher in winter as compared to spring in both control (8.25±0.21 and 7.01±0.31 ng/ml) and treatment (7.74±0.14 and 6.71±0.30 ng/ml) group of animals. When an animal is subjected to ambient cold, thyroid hormones are released to promote catabolic pathways that favor body thermogenesis. Feeding with Jaggery and fenugreek decreases the need of increased metabolism in the cold climate by cows thus decreasing the levels of thyroid hormones as in the present study. Shijimaya et al., (1985) observed increased levels of thyroid hormones under cold conditions in Holstein-Friesian cows. The physiological role of the thyroid hormone is to balance heat loss by regulating heat production (Kriesten, 1981). Thyroid hormones maintain and regulate heat production by stimulation of the expression of the thyroid hormone uncoupling proteins that leads to increased heat production. Therefore their role in cold adaptation is important (Reed, 1995). Thyroid hormones, in conjunction with catecholamines, may also play a role in increasing heat production, since their plasma concentrations are usually greater in cold adapted animals (Christopherson et al., 1978).

Supplementation by energy sources and galactogogues is an efficient mechanism to overcome drop in milk production in dairy cows of temperate Kashmir during long winter months and needs quantification at an earliest possible to overcome economic losses among poor and marginal farmers.