Impact of shearing on body weight and serum total proteins in ewes

The aim of the present study was to evaluate the influence of shearing ewes during summer season on the evolution of body weight and serum total proteins. Forty Valle del Belice (Sicily, Italy) ewes, clinically healthy and well-fed, were divided into two groups of 20 subjects each. Twenty ewes were let unshorn as a control group (Group A) and 20 ewes were shorn (Group B). All animals were weighed using a mechanical balance in the morning before shearing and the measurements were repeated for each subject of Groups A and B after shearing (1 day) and after 7, 15, 30, 45, 60, 75 and 90 days from the shearing. In experimental days climatic conditions were recorded and temperature humidity index was calculated. Blood samples were collected by means of a jugular venipuncture and were centrifuged; and the obtained sera were separated to assess serum concentration of total proteins. Two-way repeated measures analysis of variance (ANOVA), followed by the Bonferroni’s test, was used to determine significant differences between two groups for body weight and total proteins. ANOVA did not show a significant effect of shearing and of time on body weight but showed a statistical significant effect of shearing and of time on total proteins. These confirm that shearing induces adaptive responses in the organism. Both shorn and unshorn ewes are subject to heat stress, but it is evident a different sensitivity to heat stress in shorn ewes in comparison with unshorn ewes. Additional key words: blood parameters, environmental condition, fleece, sheep.


Introduction
The maintenance of the homoeothermic condition in ewes is influenced by the characteristics of their fleece, which are correlated to age, breed, sex and to temperature, relative humidity and wind (Sleiman and Abi Saab, 1995).Studies of shorn and unshorn ewes, exposed to extreme environmental conditions, have long demonstrated the importance of the fleece for the maintenance of homoeothermic conditions (Mcfarlane, 1968;Whittow, 1971).
Ewes are most commonly shorn once a year; however, shearing takes place twice annually in some localities of the world (Dy ´rmundsson, 1991), so some researchers evaluated the effects of shearing at the end of summer and at the end of winter (Hetem et al., 2009).The traditional shearing time is spring and early summer, in particular in southern Italy the production system of ewes involves shearing at the beginning of summer to coincide with favorable climatic conditions (Dy ´rmundsson, 1991).The removal of the fleece in animals adapted to grazing under the sun at the hottest times of day is considered a necessary practice by the shepherds, not only for hygienic reasons, but also to enable animals to better withstand exposure to high temperatures.In contrast with this traditional practice, it has been recognized that, for ewes, a mean of defense against external factors is its woolen coat that helps to create good thermal conditions to enable normal physiological, functional and hence, productive process (Avondo et al., 2000).Previously, the important role of shelter's microclimate on the welfare of animals, with a subsequent optimization of productive performance, was showed (Piccione and Caola, 2003;Piccione et al., 2003).The effect of shearing on physiological and haematochemical parameters was reported by several researchers (Symonds et al., 1986(Symonds et al., , 1988;;Dy ´rmundsson, 1991;Piccione et al., 2008a,b), and some of them demonstrated the influence of shearing on heat stress.However, the literature provides only little information about effects of shearing ewes on lamb birth weights (Austin, 1977) and on level of hydration (Pennisi et al., 2004).On this basis, the aim of the present study was to evaluate the influence of shearing during summer season on the evolution of body weight and serum total proteins in Valle del Belice (Sicily, Italy) ewes.

Material and methods
The study was carried out in a farm located in Valle del Belice, Sicily (38°12' N; 13°32' E) at an altitude of 300 m.a.s.l.Environmental temperature was measured by means of a thermometer freely exposed to the air but shielded from radiation and moisture.
The study was conducted on 40 pregnant, two-yearsold, clinically healthy and well-fed, Valle del Belice ewes.As concerning feeding conditions, all animals were fed in the field daily on hay (2 kg), wheat straw (1 kg), wheat concentrate (0.5 kg) and water ad libitum.
The following experimental protocol was used: the animals were divided into two groups (Group A and Group B), each of twenty animals.The ewes in Group A were let unshorn, as a control group, while the ewes in Group B were shorn.
All animals were weighed using a mechanical balance in the morning before shearing and after shearing (1 day) and were repeated after 7, 15, 30, 45, 60, 75 and 90 days from the shearing date.In experimental days blood samples were collected by means of a jugular venipuncture.Samples were centrifuged at 3,000 rpm for 10 min; and sera were separated and stored at -4°C until analyses.In each individual sample, serum concentration of total proteins was analysed with a commercially available kit by means of a UV spectrophotometer (model Slim SEAC, Firenze, Italy).Body condition score (BCS, 0 to 5 scale; Russel et al., 1969) was assessed before shearing and 45 and 75 days after shearing.
Statistical analysis was performed using the average values of the data obtained.Two-way repeated measures analysis of variance (ANOVA) was used to determine significant differences.It was used for assessment of effects due to shearing and time.P values < 0.05 were considered statistically significant.Bonferroni's test was applied for post-hoc comparison.Data were analyzed using STATISTICA 7.0 (Stat Soft Inc.) software package.

Results and discussion
Average mean, min and max value of the environmental temperature and relative humidity levels on the experimental days are presented in Table 1.Also THI values, calculated at the sampling (11.00 a.m.) of experimental days considered, are shown in Table 1.
The average values of body weight and total proteins, together with standard deviation of the means (SD) and with the relative statistical significances, for Groups A and B, are presented in Table 2. Two-way ANOVA did not show a significant effect of shearing and time on body weight.Instead ANOVA showed a statistical signif icant effect of shearing on total proteins (F (1,266) = 1.55, p = 0.008) and a significant effect of time on total proteins (F (7,266) = 17.32, p < 0.0001).Figure 1 shows the pattern of mean value of total proteins and temperature in ewes of Groups A and B during the experiment.
Also two-way ANOVA was applied for BCS, showing that BCS did not change.Table 3 shows the average values and standard deviations (SD) of BCS in Group A (unshorn ewes) and in Group B (shorn ewes) before shearing, 45 and 75 days after shearing.
Our results suggest the influence of the fleece in ewes on serum concentration of total proteins.The shearing, in fact, has not a significant effect on body weight in ewes because the removal of the fleece, considered a necessary practice for hygienic conditions, does not involve a signif icant difference in weight between the two groups, since the weight of the fleece is minimal (0.80 kg).On the contrary, the response of total proteins was of particular interest.The removal of the fleece, in fact, results in changes in the metabolism of proteins in relation to exposure to heat stress (Marai et al., 2004(Marai et al., , 2007)).The changes in serum concentration of total proteins may be due to fluid shift between the compartments of the organism that assume an important role as far as the physical protection in comparisons of the temperature.The exposure of ewes to elevated ambient temperatures, the main environmental stressing factor that impose strain on animals (Finch, 1984;Silanikove 2000), induces an increase in the dissipation of excess body heat, in order to negate the excessive heat load (Marai et al., 2007).As previously observed for haematocrit values, the total proteins concentration was lower in unshorn ewes in comparison to the shorn ewes, and these values indicate a higher level of hydration in these animals (Pennisi et al., 2004).Therefore, it is possible to evidence a haemoconcentration characterized from an increase of total proteins in shorn ewes (Piccione et al., 1994).Haematocrit value and total proteins concentration reflect changes in plasma volume that in this case did not involve significant haemodynamic consequences, although it is known that an increase in the haematocrit or total proteins corresponds to an increase in the viscosity of the blood producing an increase in arterial pressure (Hales et al., 1973(Hales et al., , 1984)).
In conclusion these results confirm that shearing induces adaptive responses in the organism.Both shorn and unshorn ewes were subject to heat stress, but it is evident a larger sensitivity of shorn ewes to heat stress in comparison with unshorn ewes.

Figure 1 .
Figure1.The pattern of environmental temperature and total proteins during experimental period in unshorn (Group A) and shorn (Group B) ewes.

Table 1 .
Average mean, minimum and maximum values of the environmental temperature and relative humidity levels during the experimental days.Temperature humidity index (THI) values, calculated at the sampling (11.00 a.m.) during the experiment
a vs g vs Day 60, P < 0.01.

Table 3 .
Average values and standard deviations (SD) of body condition score (BCS) in Group A (unshorn ewes) and in Group B (shorn ewes) before shearing, 45 and 75 days after shearing