The average environmental parameters recorded during the experimental trial are provided in Table 1.
Table 1: Environmental condition during the experimental period
Parameter
|
Open house
|
Closed house
|
Minimum Temperature (⁰C)
|
0.35
|
8.32
|
Maximum Temperature (⁰C)
|
8.11
|
11.38
|
Minimum relative humidity (%)
|
56.53
|
59.63
|
Maximum relative humidity (%)
|
82.90
|
76.41
|
Wind Chill Index (WCI)
The results have been presented in Table 2 and Figure 1. The minimum value of WCI was observed during week-10 while the maximum value was observed in week-1 in both open and closed housing systems. Swarnkar et al. (2018) classified WCI (kcal/m2/h) as no chill (<300.0), low (<300.1–350.0), moderate (350.1–400.0), high (400.1–450.0) and extreme (>450.1). Throughout the study period (January to March) extreme wind chill was observed in the open house while the animals seemed to be in the comfort zone in the closed house. In this study, though extreme wind chill was observed in the open houses but no detrimental effects were reflected in dams as well as lambs. Only one death each in open and closed house was reported. Changthangi sheep are native to cold climate and thus can tolerate wide extremes as depicted in the results.
Table 2: Wind Chill Index
Week
|
WCI (kcal/m2/h)
Open house
|
WCI(kcal/m2/h) Closed house
|
At Tmin
|
At Tmax
|
At Tmin
|
At Tmax
|
1
|
756.57±28.85
|
592.41±15.51
|
300.90±2.42
|
258.30±3.0
|
2
|
719.02±56.56
|
556.21±32.80
|
283.50±3.6
|
257.25±1.71
|
3
|
701.34±17.29
|
611.34±22.98
|
286.35±6.12
|
262.65±4.60
|
4
|
713.35±22.47
|
559.39±40.36
|
291.90±3.53
|
259.80±1.09
|
5
|
710.74±32.58
|
600.75±32.82
|
268.20±1.88
|
246.45±3.21
|
6
|
749.82±41.63
|
595.14±21.98
|
278.25±5.96
|
248.70±4.27
|
7
|
672.07±16.13
|
515.72±26.89
|
258.00±2.19
|
225.15±4.12
|
8
|
718.28±17.17
|
468.15±9.57
|
261.15±5.23
|
229.65±3.89
|
9
|
711.80±29.11
|
458.11±38.09
|
239.10±5.79
|
202.65±5.16
|
10
|
629.63±19.35
|
431.27±24.64
|
220.05±3.83
|
184.35±5.77
|
Animals try to cope up with the environmental stresses by physiological adjustments. For implications following physiological parameters were recorded on weekly basis during the entire trial period.
Pulse rate: The changes in pulse rate in experimental ewes during the trial period have been presented in Table 3 (a). In general marked variations were observed in all the groups but G2 showed higher pulse rate (beats/min) during most of the weeks than other groups. It was concluded that the animals kept inside with extra nutrient supplementation had significantly (P<0.05) higher pulse rate than the animals kept outside the shed although it was within the normal range. Results similar to present findings have been reported earlier (Rathwa et al., 2017) in indigenous sheep. Results contrary to present findings have also been reported earlier in Indian goats (Banerjee et al., 2015), Malpura lambs (Maurya et al., 2013) and new born Merino lambs (Slee et al., 1991) wherein they reported higher pulse rate in the animals kept outside. Decrease in pulse rate in animals kept outside could be attributed to physiological response of ewes to conserve energy.
Table 3(a) Pulse rate (beats/min) of Changthangi ewes (Mean ± SE)
WEEK
|
G1
|
G2
|
G3
|
1
|
73.09 ± 3.7
|
82.77± 5.3
|
75.33±2.11
|
2
|
73.31± 2.62
|
76.66 ± 2.77
|
69.33±3.31
|
3
|
69.42±1.47b
|
57.42±4.99a
|
64.66±2.92ab
|
4
|
79.33±3.39b
|
78.00±2.33b
|
70.00±2.39a
|
5
|
66.66±1.49
|
68.00±2.41
|
73.33±3.68
|
6
|
76.66±2.04b
|
72.66±1.63ab
|
69.33±1.76a
|
7
|
70.33±1.53a
|
71.33±1.13a
|
81.33±4.09b
|
8
|
68.00±0.76a
|
77.33±1.67c
|
72.66±2.04b
|
9
|
80.00±3.0
|
84.00±3.00
|
84.33±3.79
|
Means with different superscript row wise differ significantly (P<0.05)
Respiratory rate
The changes in respiratory rate (breaths/min) in experimental ewes during the trial period have been presented in Table 3 (b). Overall, it was found that G3 had significantly higher (p<0.05) respiration rate followed by G1 and G2 which implies that ewes reared in open house had higher respiration rates. Results similar to present findings have also been reported earlier in Indian goats and Malpura lambs (Banerjee et al., 2015 and Maurya et al., 2013) wherein they reported that animals in open house had higher respiratory rate than those provided protection against the cold weather. Exposure to cold leads to increase in BMR thereby leading to an increase in the respiratory rate. Increase in respiration rate may be reaction of homoeothermic animals to cold stress by enhancing the thermoregulatory mechanism to avoid undesirable increase in rectal temperature as has been reported earlier (Maurya et al., 2013).
Table 3 (b) Respiratory rate (breaths/min) of Changthangi ewes (Mean ± SE)
WEEK
|
G1
|
G2
|
G3
|
1
|
24.7±1.27a
|
23.33±0.60a
|
29.66±1.15b
|
2
|
27.33±0.99b
|
23.210.63a
|
26.66±1.03b
|
3
|
23.28±1.77
|
27.14±1.39
|
24.16±1.06
|
4
|
26.33±0.68b
|
22.66±0.94a
|
25.33±1.39ab
|
5
|
26.66±0.99ab
|
29.0±0.88b
|
25.83±0.85a
|
6
|
35.0±3.94
|
28.0±0.93
|
35.33±3.25
|
7
|
32.66±0.99b
|
30.66±1.58ab
|
28.33±0.87a
|
8
|
29.33±1.39
|
33.33±2.26
|
34.0±0.71
|
9
|
32.66±1.74
|
32.66±1.46
|
34.66±0.44
|
Means with different superscript row wise differ significantly (P<0.05)
Rectal temperature
The changes in rectal temperature (°F) in experimental ewes during the trial period have been presented in Table 4.6 (c). In general it was found that G3 had higher values followed by G1 and G2. The rectal temperature (ºF) varied throughout the study period but overall higher values were observed for the group kept outside or exposed to cold. Results similar to present findings have been reported earlier by Maurya et al. (2013) and Doubek et al. (2003) in Malpura and Merino and Romney sheep wherein they reported that animals in open house had higher rectal temperature than those provided protection against the cold weather. Ekpe and Christopherson, (2000) concluded that both cold exposure lowered rectal temperature which is in contrast with present findings wherein animals housed outside with no supplementation had higher rectal temperature. Increase in rectal temperature might be as a result of activation of the thyrotropic axis together with shivering thermogenesis (Doubek et al., 2003). The hypothalamic-pituitary-thyroid (HPT) axis plays an essential role in the maintenance of metabolic homeostasis in response to alterations in metabolism and external environment. From the present study it can be concluded that Changthangi sheep are well adapted to climatic extremes and maintain homeostasis even under cold conditions.
Table 3(c) Rectal temperature (°F) of Changthangi ewes (Mean ± SE)
WEEK
|
G1
|
G2
|
G3
|
1
|
100.03±0.37a
|
100.61±0.39ab
|
101.61±0.15b
|
2
|
98.73±0.54a
|
100.23±0.75b
|
100.91±0.29b
|
3
|
98.31±0.35a
|
98.71±0.3a
|
100.93±0.27b
|
4
|
101.69±0.24
|
101.61±0.25
|
101.86±0.25
|
5
|
102.30±0.12b
|
102.43±0.16b
|
101.33±0.18a
|
6
|
102.23±0.24b
|
101.20±0.15a
|
102.56±0.22b
|
7
|
103.13±0.13b
|
102.10±0.21b
|
101.73±0.12a
|
8
|
102.76±0.09
|
102.80±0.10
|
103.0±0.08
|
9
|
102.33±0.21b
|
100.13±0.55a
|
101.80±0.19b
|
Means with different superscript row wise differ significantly (P<0.05)
Performance parameters
Managemental interventions reflect in the overall performance of the animals. Since different managemental interventions were adopted in the present study, a regular assessment of performance parameters was made in order to evaluate their effects which are discussed under following headings.
Effect of managemental interventions on fortnightly dam weight
Results obtained have been presented in Table 4. Overall, higher body weight (Kg) was obtained in G2 followed by G1 and G3. Results similar to present findings have been reported earlier (Maurya et al., 2004; Chaturvedi et al., 2003; Mohamed and Abdelatif, 2010) wherein ewes raised on supplementary feeding showed better performance in terms of weight gain. The experimental period coincided with the gestation period which is associated with foetal growth and hence increase in dam weight. Higher dam weight in supplemented group could be attributed to better nutrition and hence better dam and lamb performance.
Table 4:Body weight (kg) of Changthangi ewes (Mean± SE)
Days
|
G1
(n=11)
|
G2
(n=11)
|
G3
(n=11)
|
0
|
27.58±1.03
|
27.66±1.09
|
27.68±0.97
|
15
|
28.29±0.75
|
30.30±0.71
|
28.11±0.82
|
30
|
29.54±0.82
|
30.63±1.06
|
28.44±0.92
|
45
|
30.83±0.87
|
32.56±1.18
|
30.02±1.16
|
60
|
32.56±1.17ab
|
34.70±1.05b
|
30.93±0.64a
|
75
|
29.76±0.73a
|
32.08±0.70b
|
28.07±0.92a
|
Means with different superscript row wise differ significantly (P<0.05)
Effect of managemental interventions on lamb weight
Results obtained have been presented in Table 5 (a). It was found that birth weight (Kg) of lambs born in G2 (3.32 ±0.15) and G3 (3.03±0.093) was significantly (p<0.05) higher than those of G1 (2.48±0.08). At 90 days of age, significantly (P<0.05) higher body weight (Kg) was observed in G2 (12.27±0.45) than G1 (10.15±0.52) and G3 (9.6±0.54) lambs. It was concluded that the animals kept inside with extra nutrient supplementation had significantly (P<0.05) higher birth and weaning weight. Chaturvedi et al. (2003) and Shah et al. (2012) reported that supplementation of extra concentrate in ewes during peri-partum period results in improvement in growth performance of their lambs in terms of body weight which is in agreement with the present findings. Higher birth weight could be attributed to higher plan of nutrition in the dams resulting in enhanced foetal growth during prenatal period while better weaning weight could be because of higher milk production in supplemented ewes.
Table 5 (a) Body weight (kg) of Changthangi lambs (Mean ± SE)
DAYS
|
G1
|
G2
|
G3
|
0
|
N=11
|
2.48±0.08 a
|
N=11
|
3.32 ±0.15b
|
N=11
|
3.03±0.093 b
|
30
|
N=10
|
6.54±0.38a
|
N=11
|
8.28±0.34b
|
N=10
|
6.36±0.30a
|
60
|
N=10
|
7.90±0.50a
|
N=11
|
9.8±0.49b
|
N=10
|
7.53±0.25a
|
90
|
N=10
|
10.15±0.52a
|
N=11
|
12.27±0.45b
|
N=10
|
9.6±0.54a
|
Means with different superscript row wise differ significantly (P<0.05)
Effect of managemental interventions on average daily gain (ADG)
Results obtained have been presented in Table 5 (b). ADG was found to be significantly (P<0.05) higher in G2 (160g/day) than G3 (110g/day) during the first month. Overall significantly (P<0.05) higher average daily gain was attained in G2 (90g/day) followed by G1 (80g/day) and G3 (70g/day) at the end of three months. Results similar to present findings have been reported earlier (Chaturvedi et al., 2003 and Shah et al., 2012). Due to faster growing rates, ADG was higher during the first month as compared to the following two months. Also, higher average daily gain (first month) in G2 could be due to higher plan of nutrition in the dams resulting in better foetal growth during prenatal period whereas as better ADG during third month could be attributed to better pastures which in turn lead to higher milk production.
Table 5 (b): Average daily weight gain (kg/day) of Changthangi lambs (Mean ± SE)
DAYS
|
G1
|
G2
|
G3
|
0-30
|
0.13±0.01ab
|
0.16±0.01b
|
0.11±0.009 a
|
30-60
|
0.04±0.005
|
0.05±0.007
|
0.03±0.007
|
60-90
|
0.07±0.003
|
0.08±0.006
|
0.06±0.007
|
0-90
|
0.08±0.005 b
|
0.09±0.004 c
|
0.07±0.001a
|
Means with different superscript row wise differ significantly (P<0.05)
Lamb morbidity and mortality
Results obtained have been presented in Table 5 (c). In the experimental groups all dams gave birth to apparently healthy lambs without any assistance. No case of stillbirth or dystocia was recorded. One mortality each in G1 and G3 was recorded during the first month wherein cause of the death was hypothermia. There was no mortality in G2 wherein the animals were kept in closed shed and given extra supplementation.
Table 5(c): Lamb morbidity and mortality
Parameter
|
G1
|
G2
|
G3
|
Sample size
|
|
11
|
11
|
11
|
Birth type
|
Assisted
|
-
|
-
|
-
|
Twin
|
-
|
-
|
-
|
Lamb mortality
|
Stillbirth/Dystocia
|
-
|
-
|
-
|
Post-natal death
|
1
|
-
|
1
|
Overall mortality
|
|
9.0%
|
-
|
9.0%
|
Economics of feed supplementation during experimental period
The results obtained have been presented in Table 6. Present study revealed that the supplementation of ewes which were kept inside the sheds during the trial period resulted in enhanced performance which was also reflected in the performance of their lambs. A net gain of Rs. 3672.15 was achieved in the group reared in a closed shed and supplemented with extra concentrate while a loss of Rs. 593 occurred in the group reared in open housing system with no supplementation. It can be concluded that the Changthangi ewes should be supplemented with better nutrition during prepartum period for better economic returns.
Table 6: Economics of feed supplementation
Groups
|
Expenditure
|
Income
|
|
Extra conc. fed
(kg)
|
Cost of extra conc. (Rs.)
|
Extra fodder fed (kg)
|
Cost of extra fodder (Rs.)
|
Additional wt. achieved (lambs+ewes+extra lamb)
|
Gross income (Rs)
|
Net income (Rs)
|
G1
|
-
|
-
|
-
|
-
|
0
|
0
|
0
|
G2
|
9
|
180
|
36
|
576
|
16.71
|
4428.15
|
3672.15
|
G3
|
-
|
-
|
-
|
-
|
-2.24
|
-593
|
-593
|