Effect of organic production system on productive and reproductive performance of cattle

The term “organic” refer to food or farming methods practiced without using artificial chemicals i.e. something natural and inherently good (Oxford Learners dictionary, 2007). The dairy animals fit well with the organic way of production and  dairy farms can convert to organic farming without major investment (Nissen, 2000), which are also more environment friendly than conventional management (Rosati and Aumaitre, 2004). Organic dairy production is drawing increasing attention because of public concerns about food safety, animal welfare and the environmental impacts of intensive livestock systems (Weller and Cooper, 1996; Sundrum, 2001).
        
In India, there is a vast scope for introduction of organic dairy farming, as India is the world’s largest milk producing country with the contribution of 17 % of the worlds milk production, has rich livestock diversity, prevalence of crop livestock integrated/mixed farming system and less dependence on market for external inputs. Our native breeds are hardy and disease resistant and therefore are more suitable to organic farming. Availability of indigenous non chemical alternatives to treatment, cheap and easily available labour, availability of good sunshine throughout the year and availability of wide geographical and agro climatic conditions offer more opportunities for converting to organic production systems in India (Chander, 2006). The liberalized Indian economy under WTO regime may also motivate the farmers to produce the milk as per the standards stipulated by FAO/WHO on food safety for export to other countries (Sehgal et al., 2006).
        
Organic milk does not contain any antibiotic residue and synthetic hormones. Recently, the percentage of organic milk production has been increased considerably on global basis. Improvement of organic milk parameters (milk yield, fat % and protein %) in the light of the organic ideas and goals is an important task. Therefore, the present study was undertaken with the objective to study the milk quality and reproductive performance of cows under organic vis-à-vis conventional system.

Experimental design and feeding
 
The present study was conducted on Jersey × Tharparkar / Red Sindhi crosses, (Jersey (½) × Tharparkar (½) and Jersey (½) × Red Sindhi (¼) × Tharparkar (¼) cattle) maintained at Eastern Regional Station of National Dairy Research Institute (NDRI), Kalyani (Nadia) West Bengal. Total 24 medium to high yielding cattle has been selected for the study, out of which 12 were reared under organic management system and 12 under conventional management system. The nutrient requirement of the animals was mostly met through concentrate and ad libitum green fodder. For cows maintained under conventional system the concentrate was fed @1.5 kg/day as the maintenance diet. Lactating animals were given additional concentrate @1.0 kg for every 2.5 kg of milk produced above 5.0 kg daily yield to meet their energy requirements. For cows maintained under organic management system, the animals were fed ad lib quality green fodder grown organically and limited quantity (1.5 to 2.0 kg/cows/day) of concentrate mixture.
 
Sample collection
 
The milk samples were taken from individual cows during both the times of milking in a day at fortnight intervals. After thorough mixing, a sample of 50 to 100 ml was taken by means of a dipper and transferred to a sample bottle with rounded corners (to avoid lodging of the milk solids) up to 3/4^th level and then bottle was corked tightly by a rubber stopper. The sample bottles were labeled properly and dispatched to laboratory in an ice box. Immediately after estimation of fat content of milk, the samples (50 ml each) were stored at 4°C after adding 2-3 drops of potassium dichromate as a preservative, until further analysis. Milk samples were warmed in water bath at 38°C and mixed well for homogenous solution.
 
Chemical analysis
 
Milk samples were analyzed separately for each cow to determine the percentage of fat, protein, total solids and solids-not-fat (SNF) content. Fat percent of milk was determined by Babcock method as per procedure described by Agarwala and Sharma (1961). Protein was determined by using Kjeldhal Method as described in AOAC (2005). Oven drying method was used for determining total solids content of milk as described by Eckles et al., (1951).
 
Reproduction parameters
 
The signs of oestrus were detected from different signs such as bellowing, mounting over other animals, less interest in feed and vaginal discharge. Animals detected in estrus in morning were inseminated in the evening on the same day and those detected in heat in the evening were served next day in the morning. After 60 days of insemination, pregnancy diagnosis was carried out by rectal palpation of the uterus.
 
Statistical analysis
 
The data were analyzed statistically using standard methods (Snedecor and Cochran, 2004) for independent samples t-test  using general linear model of SPSS version 17 and Duncan’s multiple range tests was applied to test the significance. Significance was declared when P value is less than 0.05 unless otherwise stated.

Reproductive performance
 
The data on various reproductive performances (Interval from calving to 1^st artificial insemination (A.I), Service period, number of A.I per conception and Calving Interval) in the conventional and organic group of cows is presented in Table 1.
 

        
Interval from calving to 1^st AI, Service period, number of AI per conception and Calving Interval were found less in organically managed cows than conventionally managed cows, but not in significant manner. Lowering of these parameters indicated better reproductive performance of cows in organic management system.
        
The interval from calving to first AI did not differ significantly between the two groups. This was in agreement to the findings of Enemark and Kjeldsen (1999). Fertility related problems such as Service period, number of A.I per conception and Calving Interval were lower in the organic group than the conventional group which is in agreement to Reksen et al., (1999); Hovi et al., (2001) and Bystorm et al., (2002).
 
Milk composition
 
The data with respect to the milk composition of the two groups of cows is presented in Table 2. There were significant differences in terms of fat % and protein % of milk between the two groups. The milk fat % was found to be significantly higher (P<0.05) and milk protein % was significantly lower (P<0.05) in organically managed group.
 

        
Similarly, Padel (2000) has reported that, overall increase % milk fat which was probably due to more roughage in the diet at organic farms. Nauta et al., (2006) found that the protein percent in milk produced on long standing organic farming system and converted to organic farming system was lower than the protein percentage of conventional farming system. Our findings agree with other studies focused on the comparison of the protein content between the two types of productions (Battaglin et al., 2009; Kuczynska et al., 2012). In contrast Butler et al., (2008) found a higher protein content in organic than in conventional milk.
        
Lower milk protein % observed in cows under organic system than the cows under conventional system, might be due to less amount of concentrate feeding to the organic cows than conventional cows (Ojha et al., 2017). The lower content of protein in organic milk can be explained by the lower amount of starch in organic diets which results into the lower amounts of concentrate in feeds provided to cows. Another reason can be the lack of sugar-rich juicy feed, which stimulates the production of butyric acid used for protein synthesis (Zagorska and Ciprovica, 2008).

The results revealed that the reproductive performance was better in cows maintained under organic production management system than their conventional counterparts. The study on milk quality in terms of composition revealed significantly (P<0.05) higher fat% of milk while lower (P<0.05) protein% of milk for the cows maintained under organic system as compared to those under conventional system. So it can be concluded that the organic management system of dairy cows can be beneficial as depicted by better reproductive and productive efficiency of cows. The further future study is recommended for betterment of this newly introduced farming system in India and to confirm the long term effect of organic farming system on these parameters.