Improved feeding and good management practices will ensure the improvement of reproductive performances of Tswana goats. Further, the study will assist farmers in rearing of goats through on-farm trials. The study will create awareness among farmers on protein supplementation feeding in order to improve growth performance and reproductive health of Tswana goats reared in extensive production systems.
Serum biochemistry parameters indicate pathophysiological states that help in identifying pathogenesis and causes of disease [45]. The aim of this chapter was to study the effects of supplementation of feed with different concentrations on Tswana goat’s serum biochemistry. Total protein, serum albumin, serum globulin, and urea are among the important serum biochemical parameters in assessing herd health status [30].
Results obtained showed that the serum glucose in this study ranged between 3.85 to 0.94 Mmol/L during the experiment which was within the normal ranges in goats (Table 1). This means that Protein supplementation in Tswana goats does not have an effect on their blood glucose.
These data were lower than the ones of [50] who in their experiment recorded serum glucose ranging between 2.78-4 Mmol/L. The results of this study are in agreement with the ones reported by [4]; [7] and [52] ranging between 2.78–3.89 Mmol/L in goats. Serum glucose is indicative of energy levels of the animal [14]. In this study, it was noted the blood glucose levels were significantly influenced by the sociological stages of the animal than the variability of Protein supplementation in goats. The significant (P < 0.05) decrease in blood glucose observed between week 16 and 24 of the experiment might be explained by the physiological change which was the beginning of puberty and early pregnancy in all animals and that all animals were put to the buck. The hormonal changes observed during puberty of early pregnancy characterised by the release by the pituitary gland of hormones such as Luteinising Hormone and Folliculo Stimulating Hormone induces stress and energy consumption in the animal. In addition, blood glucose levels can be affected by the adaptation mechanism which is influenced by high ambient temperatures [11]. This can be the case of this study because of high temperature in which the experiment was done.
Data obtained in this study are in line with the ones of [50] who also observed that blood glucose was not affected with the increase of tannin-rich sericea lespedeza inclusion level increased in the diet of Kiko crossed male kids.
In this study, serum albumin is indicative of the liver function in the animal [5] was also fund not to be affected by protein concentration in feed of the three treatments. No significant differences (P < 0.05) were observed between the three groups (Table 2). However, as for the blood glucose, serum albumin was influenced by metabolic and physiological changes in animals. The increase of concentrations observed between 24 and 32 weeks of the experiment were due to the fact that all animals were pregnant. These results are in agreement with the findings of [10]; [44]; [37] and [5] who in their respective experiment did not also observe a significant influence of supplementation on serum albumin of goats.
It is important to mention that albumin is a water-soluble protein found in blood accounting for about 60% of plasma proteins found in the blood. Albumin’s main function in blood is to carry fatty acids, thyroid hormones, and steroids [28]. It can also be used as a binding point for some medications and drugs. According to [5] serum albumin variations could be affected by many factors such as heat haemoconcentration that can take to an increase in its value. This explained also seasonal variations observed in serum albumin concentrations in goats during his experimental study.
The progressive increase of albumin from week 20 to week 36 of the experiment corresponds to puberty and pregnancy physiological stages for goats. This increase cannot be explained but might be due to protein levels in feed. Other of studies [5]; [41] and [58]) have noted similar lar decrease in serum albumin concentration in their respective studies. It is known that the main function is to regulate the Oncotic pressure of blood and that higher albumin levels may be caused by acute infections, burns, and stress from surgery or a heart attack [36]. Hence their increase in this study could have been due to some kind of stress related to physiological changes or environmental effects such as heat that animals may have uncounted during the experiment.
Results obtained showed significant statistical differences (P < 0.05) in albuglobulin concentrations between the three treatments with high concentrations noted in treatment 3 followed by 2 and 1 (Table 3). This led to the conclusion that protein supplementation had an impact on albuglobulin levels in treated goats. No significant differences were observed over time. It is important to mention that there is a correlation between serum proteins, albumin, creatinine, and urea [39].
The study did not find significant differences (P < 0.05) between the three treatments in regard to urea concentrations over the experimental period. However, significant differences were observed between the three (P < 0.05) with Diet three showing higher concentrations followed by diet 2 and 1 respectively (Table 4). The difference showed that protein supplementation to Tswana goats had an effect on the urea concentrations. This differentiation might be explained by the fact that urea is a protein degradation by-product which accumulates in blood if the kidney is affected or if the threshold has been reached. Urea is also known to be a nitrogen source used for the synthesis of proteins in the digestive system. In addition, the concentration of Urea in blood is always indicative of o more efficient utilization of amino acid [7].
However, it was noted that the physiological stages of goat did not significantly influence urea concentration in the treated groups. In addition, it was noted that there was no increase in concentration in treated group over time which could be explained by the fact that urea is used as a source of energy in ruminants as the nitrogen portion of urea is used as the building block for the production of protein by rumen microbes [28].
Data obtained in this study also showed significant correlation between protein supplementation in Tswana goats and total protein concentration in blood. Significant differences (P < 0.05) were observed between the three treatments. Higher concentrations of serum total protein were respectively observed in treatment 3; 2 and 1 during the experimental period. There was a slight increase in Total protein concentration from week 16 to 36 of the experiment which corresponded with puberty and pregnancy while after parturition, significant increase of concentrations was observed in all three treatments (Table 5). These results are in line with the ones of [10]; [3]; [35] who in their studies observed an increase of total protein after parturition in goats and bovine. The increase during post- partum could be explained by the increase of globulin and production of immunoglobulin necessary for the neonate immunity and growth [8]. This showed that there was a correlation between physiological stage and total protein concentrations over time of experiment. Results obtained in this study did correlate with the study of [5] who in their study observed a decrease in serum total protein after supplementing the Karroo leaves to goats.
The study revealed that protein supplementation had effects on serum lipase and globulin concentration in blood same as for serum total protein, between the three treatments. High concentrations were respectively observed in treatment 3, 2 and 1. This difference in concentration could be explained by the supplementation of protein in feed and it know that globulins are large proteins that plays an important role in the immunity of the animal (Table 6). The light increase observed during pregnancy as observed in this study is in correlation with the findings of [16]; and [2] who got similar the total proteins, α1-globulins, β-globulins, γ-globulins and albumin/globulin which could be explained by the stress incurred during pregnancy. This confirms that physiological changes had influences on the Globulin concentrations in Tswana goats [12] concluded also that the pattern of serum protein concentrations could give information regarding the level of dehydration, plasma volume expansion and hepatic function occurring during the peri-partum period including the milking period. Due to high temperatures recorded in the study area, heat stress although animals were having access to water ad-libitum, might explain the increase during the study period. However, [18]; [7] and [55] have also reported a decrease of serum total protein and globulin after the milking period. This could be explained by the fact that during the peri-partum the increase of globulin concentration result in the formation of immunoglobulin [13] and mostly lactation period, lipogenesis and esterification are reduced leading to free fatty acid mobilisation by an increase in in nor-epinephrine and epinephrine secretion.
The findings of this study on serum cholesterol did not show significant differences between the three treatments. Significant decrease observed between week 16 and 28 corresponded with stress and increased energy requirements due to pregnancy and lactation. This also show that protein supplementation did not have effect on serum cholesterol concentration in Tswana goats (Table 9). During energy demand period such as pregnancy and lactation, the decrease in protein, albumin and cholesterol might be due also to catabolism of total protein and supply of energy to the mammary gland [59]. Other authors [6]; [33] believe that level of total serum protein correspond with the survival of kids. This because the serum total protein and immunoglobulin fractions are necessary for the neonate immunity and growth. Results of this study are similar to the one obtained by [40] and [9] who observed total protein and globulin were not significantly influenced by the dietary treatments, and in pregnant does, restricted feeding showed no minor or no changes in the concentrations of serum total protein, triglycerides and cholesterol during the study conducted by [49] (Tables 8 and 9). [21] confirmed that, cholesterol is used to diagnose hepatic damage in domestic animals. He, furthermore, stated that increased cholesterol levels are risk factors for heart, disease, while reduction in serum cholesterol indicates inadequate liver function, malnutrition, stress, decreased nutrient intake and hormonal insufficiency. In addition, other studies have shown that serum levels of cholesterol could be indicative of the absence of dyslipidaemia, also known as hypercholesterolemia [41]. Dietary protein had a significant effect on urea in weeks 12 and 36. These results are not in agreement with the ones reported by [1]. The results showed that there was no significant difference reported in urea concentration in goats during his study. However, the lowest value was reported in diet 3 while diets 2 and 3 possessed the highest values. In week 36 high values were reported in diets 1 and 3, while diet 2 had the lower value of urea. Although significant differences (P < 0.05) were observed between the treatment’s diets on the fore mentioned serum chemistry, it was not attributable to diets effects because they are within the normal range and they are capable of performing their function.
[21] revealed that cholesterol is used to diagnose hepatic damage in domestic animals. He, furthermore, stated that increased cholesterol levels are risk factors for heart, disease, while reduction in serum cholesterol indicates inadequate liver function, malnutrition, stress, decreased nutrient intake and hormonal insufficiency. During the study by in addition, levels of serum cholesterol in animals could be indicative of the absence of dyslipidaemia, also known as hypercholesterolemia. Similar findings were reported by [42] when goats were fed tannin-rich forage.