Effect of Chromium Treatment on Growth and Some Blood Parameters of Local Lambs in Hot Climates

This study was conducted in the animal field of the Department of Animal Production in the College of Agriculture - University of Tikrit for the period from 7/6/2022 until 7/9/2022. by (93) days, preceded by an introductory period for a period of (13) days to study the effect of chromium treatment on productive traits represented in growth (weight gain) and some blood parameters and biochemistry and the concentration of some hormones. (15) Awassi lambs were used in this experiment, their ages ranged between 4-5 a month and with an average initial weight of 22.6 + 0.9 kg, the experimental treatments were divided into three treatments distributed randomly. on three transactions. The first transaction is the control and treatment the second is addition chrome on Chromium Yeast form at 0,5 mg / day / lamb and the third transaction is addition of Chromium 1 mg / day / lamb, five lambs for every transaction. The results indicated that there is Significant increase (P ≤ 0.05) between treatments in the rate of daily weight gain of lambs, as the third treatment (1 mg chromium / lamb / day) excelled compared to the first treatment (control) that was free of additives, and the second treatment contained (0.5 mg / lamb / day). These results were reflected in the total weight gain of the lambs, as the third treatment (1 mg chromium /day/lamb) was significantly superior (P ≤ 0.05) at a rate of (16.35) kg compared to the first treatment. (control) (9.85) kg and the second (0.5 mg / day / lamb) (10.92) kg. The results also showed that there was a significant (P ≤ 0.05) superiority of the third treatment (1 mg chromium / day / lamb) in the efficiency of feed conversion at a rate of (5.53 fodder/kg meat) Compared to the second and third treatments (7.68 and 9.64 feed/kg meat), respectively, It was also seen there are no differences between the treatments in the daily feed consumption rate. With regard to the results of blood biochemical characteristics (glucose, cholesterol, total protein) at the end of the experiment, there was a significant increase in glucose, as the third treatment recorded a significant increase (P ≤ 0.05) in its concentration compared to the second and first treatment, while the hormone thyroxine was recorded. T4 significantly increased (P ≤ 0.05) for the third treatment (1 mg chromium / day / lamb) at a rate of 8.202 nano moles / liter Compared to the first and second treatment (0.5 cholesterol / lamb / day) at a rate of 4.165 and 6.360 nano moles / liter respectively, In general the study showed that the addition of chromium to the diet led to an improvement in the weight of the lambs, achieving a significant weight gain and improving the efficiency of feed conversion in the Awassi lambs.


Introduction
Animal productivity is negatively affected by environmental factors, including a high ambient temperature that causes heat stress, and here the animal is forced to adapt to the external environment, which is a typical response developed by the animal with a change in its environment.This results in reduced feed intake, increased respiration rate, decreased activity, and increased water consumption to facilitate the dissipation of excess heat [1].The reports of the International Food and Agriculture Organization [2], during recent decades indicates that the demand for animal products in the Near East and North Africa region, which includes all Arab countries, will rise to higher rates than the rates of production.Therefore, animal production should be increased in general and special attention should be given to raising sheep because they are preferred in the region.Goats are the most prevalent in this region, and the production of fodder must increase in proportions equal to the rates of increase in the number of animals, so that this increase can keep pace with the requirements for improving the productivity of each animal in different environments.[3], Explained that sheep are considered one of the most important livestock in Iraq and are raised for the sake of meat, milk and wool , and the Awassi breed is widespread in Iraq on a large scale and is the dominant type in Iraq.It represents about 60% of the Iraqi sheep, and is raised mainly for the production of meat, milk and wool [4].One of the administrative methods used to improve the efficiency of growth and composition of carcasses is the use of feed additives with diets .Chromium is one of them, as it is a major factor involved in the metabolism of carbohydrates, protein and fats by enhancing the effectiveness of the hormone insulin [5,6], it increases the manufacture of glycogen from glucose) Glycogenesis [7].It raises the cells' intake of amino acids and glucose , in addition to its role in reducing the levels of lipids, total cholesterol, low-density cholesterol (LDL) and increasing high-density cholesterol ( HDL) in the blood [8].[9], indicated that the animals' need increases according to several factors such as heat stress.Hence, due to the lack of studies that dealt with the issue of the effect of chromium on growth rate, feed conversion efficiency, and immune status in hot climates for Awassi lambs in particular, this study was conducted to find out the effect of chromium treatment on productive performance and immune status in hot climates of local Awassi lambs .

Materials and Methods
This study was conducted in the animal field of the Department of Animal Production in the College of Agriculture -University of Tikrit and laboratories in Musel university Ethical approval No. um.VET.2021.5 for the period from 7/6/2022 until 7/9/2022 .By ( 93 ) days , preceded by an introductory period of (13) days for the lambs to acclimatize to the concentrated diet, Table No. (1).(15) Awassi lambs were used in this experiment , as they were obtained from the local market in Salah Al-Din Governorate, their ages ranged between 4-5 .A month with an average initial weight of 22.6 + 0.9 kg, as the lambs were weighed after the end of the preparatory period and two consecutive days after cutting off the feed for a period of 12 hours, for the purpose of stabilizing the initial weight using an electronic field balance.Lambs were distributed into three feeding groups according to weight, with five lambs for each group, as the average weights of those groups were close (22.550± 0.18).and ( 22.200 ±0.26 ) and (21.950 ± 0.14) kg, respectively, and the experimental treatments were distributed randomly to the groups , and the lambs were numbered with plastic numbers in addition to placing the lamb numbers .For each treatment on each cage of the breeding cages, the feeding system ( groups ) was applied to the lambs of the experimental treatments .wheat ) and a 5-liter drink of water , and cubes of mineral salts were placed in front of the lambs throughout the duration of the experiment.The experimental treatments were divided into three treatments distributed randomly on three transactions .The first transaction was the control and treatment the second addition was chrome on chromium Yeast form at 0,5 mg / day / lamb And the third transaction was addition chrome on chromium Yeast form 1 mg / day / lamb and reality five lambs for every transaction .I provided a fixed diet concentrated from fodder center to all animals transactions has been added chrome to the fodder throughout a period search and extreme 93 Day.

Weight and Weight Gain
The lambs were weighed at the beginning of the experiment, and the weighing continued every week until the end of the study, to identify weight gain and monitor growth.The weighing process was carried out using a special scale with a capacity of 150 kg and divisions of 0.1 kg, and the difference in weight gain was calculated according to the following equation: Weight gain (kg) = subsequent weight -previous weight

Feed Conversion Efficiency: Feed Conversion Ratio
The feed conversion ratio for experimental lambs was calculated by dividing the concentrated feed consumed by the amount of weight gain.

FCR=(Consumer feed)/( Weight gain)
Also, blood samples were collected after the feed was removed from the animals before the blood sampling process for a period of 12 hours so blood samples were drawn from the jugular vein in the neck area using a wine syringe with a capacity of 10 ml and placed in plastic tubes free of anticoagulant .After that they were placed in a centrifuge (3000 cycles / min* for 20 minutes to separate the blood serum from blood ).The rest of the components , the serum was kept in tightly sealed tubes in the (frozen) at a temperature of ( -20 ° C ) until the biochemical tests were conducted , and the tests and analyses were carried out in an external laboratory.
The Statistical Analysis System - [10], was used in data analysis to study the effect of different coefficients on the studied traits according to a complete random design ( CRD ) , and the significant differences between the averages were compared with the [11] multinomial test.
The mathematical model for design: ( Mathematical Model ).

Yij = µ + Ti + eij
So that: Yij : the observed j value of transaction i .µ : the overall average for the studied trait.Ti : effect of treatment i .eij = the experimental error that is normally and independently distributed with a mean of zero and an equal variance of ℮ 2 σ .

Average Daily Weight Gain
Table (2) indicates that there are significant differences ( P≤0.05 ) between the treatments in the rate of daily weight gain of lambs, as it was significantly superior ( P≤0.05 ) to the third treatment, which was given (1 mg / lamb / day) chromium at a rate of (170) g / lamb / day compared to the first treatment that was devoid of additives (breeder's diet) at a rate of (90) g/day/lamb and the second treatment that was given (0.5 mg/lamb/day) chromium at a rate of (120 ) g/ lamb / day, and the superiority in body weight and rate of weight gain may be attributed to the positive effect of chromium on growth by stimulating the growth of the mucous membrane of the small intestine and thus increasing its absorption of feed and increasing the efficiency of feed conversion [12].Or that chromium increased the effectiveness of carbohydrate, protein and fat metabolism by enhancing the activity of the hormone insulin [5,13].

Average Weekly Weights During the Experiment
We note from Table (3) that there are no significant differences between the experimental treatments during the first three weeks, but a significant superiority ( P≤0.05 ) was observed for the third treatment compared to the first and second treatment during the fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh and second weeks.Ten and thirteen , but in the same last ten weeks of the experiment showed a non-significant superiority ( P≤0.05 ) for the second treatment compared to the first treatment (control) .
The reason for this significant superiority of the third treatment in terms of weekly weight gain may be due to the positive effect of chromium in increasing the feed intake and improving the efficiency of the consumed feed.[14], which is consistent with the results reported by [15].(*) means that there are significant differences ( P < 0.05 ) .

Overall Rate of Increase
It can be seen from table (2) that there are significant differences ( P≤0.05 ) between the treatments in the rate of total weight gain of lambs, as the third treatment that was given (1 mg/ lamb /day) chromium was significantly superior ( P≤0.05 ) at a rate of (16.35) kg .On the first treatment (control) (9.85) kg and the second ( 0.5 / day / lamb ) at a rate of (10.92) kg , while there were no significant differences between the first and second treatments, this superiority in the final weight of lambs is a result of the superiority of that treatment in the rate of the total and daily weight gain and the final weight rate, and this result is a natural reflection of the daily and weekly weight gain rate that was previously discussed.

Final Weight
Table (2) shows the final weights of the transactions on Tuesday, which amounted to (31.1 0, 33.6 5, and 39.0 2 ) .kg, respectively , as it was noted that the third treatment was significantly ( P≤0.05 ) superior to the first treatment (control) and the second treatment, although there were no significant differences in the amount of feed consumed (dry matter), and the reason for this improvement in weight gain may be attributed to the role of Chromium inside living tissues works to increase the entry of nutrients to them, especially amino acids and glucose, and chromium works to change the concentration of insulin, which leads to an increase in the consumption and absorption of amino acids within the muscle tissue and an increase in its sedimentation and thus an increase in building muscle tissue [16].

The Initial Dry Matter and Conversion Efficiency Food
Through table (2) we notice that the third treatment was significantly superior ( P≤0.05 ) in the amount of feed consumed at a rate of 1.1 kg / day , compared to the first and second groups , where the average daily feed consumption was 0.86 and 0.89 kg / day, respectively, as well .Note there is superiority In feed conversion efficiency for each of the second and third treatments (7.68 and 5.53 feed/kg meat), respectively, significant ( P≤0.05 ) compared with the first treatment ( 9.64 feed / kg meat), and the third treatment was significantly superior ( P≤0.05 ) in the efficiency of feed conversion over the second treatment .

Biochemical Characteristics and the Concentration of some Hormones in the Middle of the Experiment
Table (3) shows the effect of chrome in the three coefficients of the experiment with regard to the blood biochemical characteristics and the concentration of some hormones ( cortisol , thyroxine and triiodo-threonine ), as a blood test was conducted in the middle of the experiment and it was found that there were no significant differences between the three treatments in the percentage of glucose in the blood of the three treatments with and the percentage of cortisol , Urea mg / dl , total protein gm/ dl , thyroxine , and triiodothreonine , for the three transactions These results agree .( NS ) means that there are significant differences ( P ≥ 0.05 ) .

Table 1 .
Materials used in the formation of experimental diets (g/kg).

Table 2 .
Effect of chromium supplementation on productive traits of Awassi lambs.
Values represent the means ± standard error.

Table 3 .
The effect of different levels of cholesterol in blood biochemical characteristics for Awassi lambs.