Bodyweight and body condition
The impact of physiological status on the body weight and body condition of Tellicherry does is depicted in Table 1. The does exhibited higher body weight and body condition during pregnancy and dry period (P<0.01) than lactation. Sudden loss in body weight and condition (P<0.01) was noticed during the early lactation. However, gradual increase in the body weight and body condition was observed as the lactation advances and the does reached their pre- pregnancy body weight and condition in the dry period after lactation. Lactation was found to affect the body weight and body condition of the does profoundly.
BCS refers to fatness or muscle status of livestock and are commonly used for animal selection in the farms. Also, BCS levels of animals are related to reproductive performance and productivity
(Serin et al., 2010). The lipid reserves of the animal changes during the breeding period, with an increase during pregnancy and mobilization at parturition and at the beginning of lactation (
Bauman and Currie, 1980). Milk production generally reaches at peak at about six to nine weeks after kidding, however feed intake levels are not affected
(Ghosh et al., 2019). It has been observed that goats are unable to eat enough to meet their energy need in early lactation, therefore, body fat reserves are mobilized to provide energy for high production (
Cimen and Topcu, 2013) indicating that does are usually in a state of negative energy balance in early to mid-lactation (
Ghosh et al., 2019) and have lowest BCS during peak lactation and there is negative relationship in between BCS and milk production (
Ghosh et al., 2019). Similar to that reported earlier, the changes were also observed in the current study.
BCS of pregnant does in the present study were in accordance with
Navarre et al., (2012) who stated that the pregnant goats should have a body condition score between 2.5 and 3. The changes in BCS during lactation period observed in the present study were in accordance with the results obtained by
Darwesh et al., (2013) who observed a lower BCS in early lactation followed by significant (
P<0.05) increase at mid as well as late stages of lactation. Similarly,
Cabiddu et al., (1999) also reported that the BCS increased as the lactation progressed. However, the present BCS findings during lactation were higher than those observed by
Sudharsan et al., (2020) who reported a BCS of 1.85±0.16, 1.95±0.09 and 2.15±0.16 in Tellicerry does during the early, mid and late lactation, respectively.
Body weight of Tellicerry does observed in the present study during early pregnancy was similar to that of
Chitra et al., (2012) who reported a body weight of 24.23±0.73 kg in adult Tellicherry does. However, significant reduction in body weight was observed during the lactation period especially during early lactation due to fat mobilization and negative energy balance.
Benchohra et al., (2015) also found a significant decrease in mean body weight during the first month of lactation in Rembi sheep.
Ishmais et al., (2004) and
Benchohra et al., (2015) also reported maximum loss in body weight during the first four week postpartum.
Haematological parameters
Haematological parameters of Tellicherry does during the different physiological status is recorded in Table 2. The physiological status was found to have profound impact on the haematological parameters of Tellicherry does; however, all the haematological values were within the reference range for goats except for the WBC count. The haemoglobin (Hb) concentration, packed cell volume (PCV) and RBC count were found to be elevated during the late gestation period. Marked decrease in PCV, Hb and RBC count were noticed during the lactation period than during gestation. WBC count was elevated in all the physiological status. However, it was elevated greatly during late pregnancy and lactation (P<0.01) than during early pregnancy and dry period.
The elevated levels of Hb and PCV observed during the early and late gestation. Contrarily, marked decrease in concentration of PCV, Hb and RBC count was evident during the lactation period compared to pregnancy period. The results were in agreement with
El-sheriff and Assad (2001). They observed an elevated PCV and Hb in Barki ewes from 10
th week of gestation to parturition than dry period and a sharp decline in PCV and Hb during postpartum period.
Salem (2017) also reported a significant reduction in RBCs, PCV and HB values were observed in lactating ewes and does.
Hassan et al., (1982), who reported a low PCV and HB concentration in lactating animals, postulated a negative association between PCV and milk production. The elevation might be due to higher oxygen consumption to meet the requirements of high metabolic rate of pregnancy while the decline might be due to stress due to lactation on the life span of blood corpuscles and hemoglobin formation or hemodilution due to increased water mobilization to mammary glands through vascular system (
El-sheriff and Assad, 2001). According to
Anwar et al., (2012) elevated erythrocyte devastation in mammary cells are responsible for low PCV% along with mobilization of water to mammary gland.
Fortagne and Schafer (1989) reported an increase in the total leukocyte count in pregnant goats around parturition and
Sandabe and Yahi (2000) also noted a significant increase in the leukocyte count of pregnant Sahel goats. The increase in total WBC in does during late pregnancy and lactation is because of the ACTH-related hormonal stress reaction (
Oduye, 1976). According to
Dellmann and Brown (1987) the stress probably stimulate the release of certain factors called leucocytosis inducing factor (LIF) and colony stimulating factors (CSF) which are known to increase haemopoietic activities and blood cells mobilization into circulation.
Biochemical parameters
The biochemical parameters of the Tellicherry does were greatly affected by the different physiological status (Table 3).
Highest LDH concentration (P<0.01) above the reference range was observed during late pregnancy early lactation and mid lactation period followed by early pregnancy and late lactation. The end of gestation and the beginning of lactation are the two critical periods where most of the changes in serum metabolic profile happen. Higher LDH activity in mammary parenchyma is required during initiation of lactation
(Visha et al., 2002). According to
Bauman and Currie (1980) during the early lactation period, high-yielding cows can be in negative energy balance. Further, metabolic diseases with impact on the liver function most commonly occur during this period with changes in the activity of LDH and LDH iso-enzymes. Thus, the elevated LDH observed during the late gestation and early lactation period is due to initiation of lactation and negative energy balance.
Elevated BUN levels (P<0.01) were observed during late pregnancy and lactation period and has been reported as a good indicator of nitrogen intake in sheep and goats
(Gurgoze et al., 2009). Animals may catabolize proteins in order to cover nutrient demand, which translates to increases in urea levels in plasma
(Canfield et al., 1990). The elevated levels of BUN observed during the lactation were in accordance with
Salem (2017) who reported elevated levels of BUN in lactating ewes and does.
Berkani et al., (2018) also observed a significant increase in uraemia level at the 7
th day of lactation compared with the last month of pregnancy in Djellal ewes. On the other hand,
El-sheriff and Assad (2001) found that uraemia began to increase from the 10
th week of gestation to maximum concentrations at parturition in Barki ewes under semi-arid conditions.
Soliman (2014) also reported highest serum urea level during late-pregnancy followed by early-lactation than non-pregnancy.
Karapehlivan et al., (2007) found that changes in blood urea concentration during lactation could depend on milk synthesis in Tuj ewes. The increase in BUN concentration is attributed to changes in protein metabolism during lactation (
Salem, 2017) and higher urea concentration in lactating ewes can be a result of catabolizing muscle protein when large amounts of body reserves are mobilized
(Antunovi et al., 2011).
The physiologic status (pregnant, dry and lactating) of animal plays a major role in regulating protein absorption and metabolism
(Gonzalez et al., 1985). Serum total protein showed a significant increase during late pregnancy and lactation period than dry period. Similar results were reported by
Piccione et al., (2009) in ewes during all (early, mid and end) lactation.
Shetaewi and Daghash (1994) also pointed out a significant rise in serum total protein concentrations in lactating Egyptian coarse-wool ewes. According to
Davson and Segal (1980) the ability to synthesize the constituents of milk appears 3-4 weeks prepartum. Thus, the elevated total protein during late pregnancy is attributed to the synthesis of milk constituents’ prepartum. Further, in lactating goats total protein level of serum increases with the progress of lactation due to the catabolism of protein for milk synthesis
(Krajnicakova et al., 2003). The higher value of total protein in lactating does compared to dry also proves the high energy need which exists in animals due to milk synthesis especially during the early lactation
(Bremmer et al., 2000).
The serum levels of glucose and triglyceride were lowest during the early lactation period and highest during the early pregnancy and dry period. Their levels started to decline as the pregnancy advances and a sharp decline in their levels were noticed during the early lactation period. However, as the lactation advances both glucose and triglyceride concentration increased steadily and reached the maximum level during the dry period.
Wazirir et al., (2010) also observed a significant reduction in glucose levels as pregnancy advanced in sahel goats. This could be attributed to the considerable glucose requirements in pregnant animals
(Parr et al., 1984). The lower level of blood glucose recorded during early stage of lactation may be ascribed to the utilization of large amount of blood glucose by mammary gland for the synthesis of lactose (
Schultz, 1968).
Salem (2017) also observed a significant reduction in serum triglycerides levels in lactating ewes and does. Significant decrease in serum triglyceride during early and mid-lactation has also been reported by
Gradinski-Urbanac et al., (1986) in sheep. During the lactation period, lipogenesis and esterification are reduced and free fatty acid mobilization is stimulated by an increase in nor-epinephrine and epinephrine secretion. The activity of lipoprotein lipase is increased in mammary gland and decreased in adipose tissue
(Manat et al., 2016). According to
Piccione et al., (2009) during lactation insulin triggered lipogenesis became incompetent and this drop in competency is manifested as reduction in serum triglycerides. Further, a strong evident suggests that in ruminants, during energy deficit the triglycerides drops
(Mazur et al., 2009). The blood triglycerides are a major element in milk fat synthesis
(Nazifi et al., 2002). During lactation phase, mammary gland uptake 80% of body metabolites to form milk
(Ouanes et al., 2011). Thus, the reduction in triglyceride level during lactation is possibly due to incompetent lipogenesis and utilization of triglycerides for milk fat synthesis.
The AST levels remain unchanged during all the physiological status. The AST and ALT seem to be good predictors of level of amino acids utilization during gluconeogenesis and therefore of body protein depletion on negative energy balances (
Caldeira and Portugal, 1991). Serum AST determinations are still part of many biochemical profiles because of their relatively high sensitivity for detection of hepatocyte injury and myocyte injury and stability in serum (
Hoffmann and Solter, 2008). The results obtained in the current study were in agreement with the results of
Kamalu et al., (1988) and
Waziri et al., (2010), indicating that liver is not clinically affected during pregnancy.
Calcium level started to decline as the pregnancy advances and it reached its minimum during the first month of lactation (P<0.01). However, it started to increase gradually as the lactation advances and reached the normal physiological range during the dry period. Phosphorus level was lower during the early and late lactation however it was within the reference range.
Calcium (Ca) and Phosphorus (P) are the major minerals, mainly stored in the skeleton and are very strongly mobilized at the beginning of lactation
(Berkani et al., 2018). Similar to that of the findings of present study, a significant reduction in blood Ca and P levels at 1
st week post-partum was observed in Ouled Djellal ewes
(Berkani et al., 2018). A decrease of Ca levels in lactating cow was reported by
Ivanov et al., (1990); Fikadu et al., (2016) and in lactating goat was indicated by
Krajnicakova et al., (2003) and observed that this decrease was in relation with the passage of Ca to the milk during lactation that leads to a several adaptation in the metabolism of this ion.
Furcht (1988) reported that the decrease in inorganic phosphorus, may be due to very low phosphorus content in the diet (animal beet leaves, silage), or components with a low portion of phosphorus that is not readily available (cereals), or a too low level of animal proteins and/or inadequate mineral supplementation. The high levels of calcium also restrict phosphorus availability and therefore necessarily lead to a too low blood phosphorus level
(Zvorc et al., 2006).
Na and K levels remain unchanged during all the physiological status. Sodium is the major extracellular cation and is responsible for most of the osmotic force that maintains the size of the extracellular fluid (ECF) compartment. Chloride is the major anion in ECF (
Russell and Roussel, 2007). In our study, changes in serum chloride tend to parallel those of sodium which is attributed to the fact that the renal reabsorption of sodium is accompanied by reabsorption of chloride (
Russell and Roussel, 2007).
