Effect of Rearing System and Physical form of the Total Mixed Ration on Growth Performance of Local Male Lambs

The University of Anbar’s Department of Animal Production hosted this experiment on their sheep farm from October 18, 2022, through January 6, 2023. Twenty-two local male lambs, ranging in age from 3.3 to 3.5 months, and averaging 20.2±2.28 kilograms were included. The purpose of the experiment was to determine the influence of the rearing system and physical form of the total mixed ration on the growth and feeding performance of local male lambs. Lambs were randomly distributed into four treatments. T1 (group housing + loose diet) included 6 Lambs distributed in three group cages (2 Lambs /cage), T2 (group housing + pellet diet) included 6 Lambs distributed in three group cages (2 Lambs /cage), T3 (individual housing + loose diet) included 5 Lambs distributed in five individual cages (1 lamb / cage), and T4 (individual housing + pellet diet) included 5 Lambs distributed in five individual cages. A total of 63 days were devoted to the actual experiment. All lambs were fed ad-libitum to the Pelleted and loose total mixed ration. Throughout the duration of the experiment, the parameters of growth and nutritional performance were estimated. The results of present experiment showed that the individual rearing system significantly improved daily feed intake and dry matter intake compared with grouped rearing system. The pelleted total mixed ration was superior to the loose total mixed ration in growth performance (final body weight, total weight gain, daily weight gain) and feeding performance (feed conversion ratio, feeding efficiency), and decreased the cost of producing 1 kg of weight gain. The results showed that the growth and feeding performance of local male lambs were significantly boosted by the interaction between individual housing and pellet diet. Researchers found that fattening lambs’ productivity might be improved with the use of individual housing combined with a pellet diet.


Introduction
Sheep are sociable creatures that do not do well when separated from their flock or introduced to new animals.When introduced to unfamiliar conditions quickly, sheep might experience stress that negatively impacts their nutrition and overall performance [1].Competition for food and space has a huge impact on how quickly animals eat when there are many of them sharing a single feeder.Even when a balanced feed is supplied ad libitum, insufficient feed intake might still occur.Due to the social synchrony of feeding observed in many domesticated species, some individuals may be barred from the trough at peak feeding times [2].However, when there are too many individuals in a group, stress, aggression, and competition can slow development and stunt 1259 (2023) 012078 IOP Publishing doi:10.1088/1755-1315/1259/1/012078 2 growth [3].When living in dense populations, animals are constantly having their personal space invaded, which can lead to hostile interactions and stress [4].Many studies have been done to find out the effect of housing density (individual or group) on the growth performance of lambs, concluded that housing density affects the behavior and feed intake of lambs and that a small number of animals in the barn improves weight gain [5].Furthermore, depending on the response of feeding behavior, lambs raised individually have better opportunities for adequate nutrition and are less exposed to stress as a result (1).The lambs reared individually and in pairs had the same growth performance with a difference in some feeding behaviors between them [6].The total mixed ration is a new way to keep up with the increase in human consumption of animal products and the lack of feed through the efficient use of agricultural crop residues and by-products [7].The total mixed ration is defined as a mixture of concentrate and roughage feed with some other complementary additives, and it is well mixed so that animals cannot consume one component without the other [8,9].Pelleted Total Mixed Ration has been expanded through the pelleting Process [10].Pelleted total mixed ration is an emergent practice replacing loose total mixedration and has been regarded as an effective feed form for enhancing feed intake, digestibility, and feed conversion efficiency [11].Due to the importance of the subject and the scarcity of studies on the effect of the rearing system and the physical form of the total mixed ration on the growth performance of local male lambs, The purpose of this research was to compare the growth performance of local male lambs fed either a loose or pelleted form of the whole mixed ration, as well as two different rearing systems (individual and group).

Materials and Methods
The University of Anbar's Department of Animal Production hosted this experiment on their sheep farm and with operation University of Mosul, College of Veterinary Medicine, in situational Animal Care and use committee, ethical approval No. Um.VET.2021.5.from October 18, 2022, through January 6, 2023.Twenty-two local male lambs, ranging in age from 3.3 to 3.5 months, and averaging 20.2±2.28 kilogram were included.The lambs were placed in two types of pens, the first of which is for individual rearing and is furnished with individual cages (1 lamb/cage) measuring 150 x 100 x 110 cm, and the second of which is for group rearing and is equipped with cages measuring 300 x 130 x 100 cm and housing two lambs per cage.There is a plastic bucket with food and another with water in each cage.The lambs were given mineral salt blocks, vaccinated against diseases caused by Clostridia bacteria, treated for internal and external parasites, and given two weeks of acclimatization to the individual cages, group cages, and new diet before the experiment began.The lambs were fed a pelleted and loose total mixed ration, as well as a locally produced diet, over time using the feed components and proportions listed in Table (1) and the results of a chemical analysis of the diet.As can be seen in Table (2), the lambs started off eating 750 gm of high-quality hay and 50 gm of experimental ration at each of their two daily meals (at 9 am and 4 pm).Thereafter, the hay was gradually reduced and the quantity of diets was increased until the lambs became completely reliant on the new diet.At the beginning of each week, before the experimental lambs were fed and watered, an electronic field balance was used to determine their weight (days 0,7,14,21,28,35,42,49,56, and 63).Weighing took place first thing in the morning, before breakfast and water.A cost-perkilogram-growth calculation was made, along with estimates for total weight gain, daily weight gain, feed intake, dry matter intake, feed conversion ratio, feeding efficiency, dry matter intake as a percentage of body weight, and overall cost.Following the General Linear Model and with the help of the pre-released SAS statistical program 9, the data was analyses in two directions (Two Way Analysis), with the first direction covering the impact of the two rearing system treatments on the traits under investigation.The second direction covered the impact of the two diet form treatments [13].The Duncan's multiple range test was used to look for statistically significant differences in the means [14].

Growth Performance
The results of this study concerning the effect of rearing system on the growth performance of male lambs (Table 3) revealed that there were no significant differences between the two rearing systems (group and individual) in terms of final weight, total weight gain, and daily weight gain.
In terms of the effect of the physical form of the complete mixed ration, the pelleted ration was superior to the loose ration in terms of final weight (35,4 kg vs. 31,4 kg respectively ), total weight gain (15,1 kg vs. 11,2 kg respectively ), and daily weight gain (240 g/day vs. 178 g/day respectively ).And regarding the effect of the interaction between the rearing system and the physical form of the total mixed ration, the results demonstrated that the interaction, individual rearing -the pelleted form was superior to the other interactions in terms of final weight, total weight gain, and daily weight gain.The results indicate that the system of raising lambs in group or individuals had no discernible effect on the growth performance of local male lambs, which is consistent with what he discovered [15].Regarding the effect of the physical form of the total mixed ration, the pelleted diet had a significant impact on the body weight and growth rate of local male lambs.Our results agreed with [16], while did not agree with [17], who found that no significant differences in the final body weight, total weight gain, and daily weight gain of Arabi lambs between pelleted total mix ration and loose total mixed ration.This difference may be attributable to the distinct breed of lambs used in the studies or to the different components and chemical composition of the diets.
As for the effect of the interaction between the rearing system and the physical form of the total mixed ration, there were no previous studies demonstrating the effect of this interference, however, it appeared from our research that the interaction of individual rearing-pelleted significantly enhanced the growth performance of local male lambs.

Feeding Performance
The effect of the rearing system and the physical form of the total mixed ration on the feeding performance of local male lambs is depicted in table (4).Regarding the effect of the rearing system, the results demonstrated that the individual rearing system was significantly superior to the group rearing system in terms of feed intake (1221, 1093 g/day respectively ) and Dry matter intake (1116, 1002 g/day respectively ).Feed conversion ratio, feeding efficiency, and dry matter intake as a percentage of body weight did not differ significantly between the individual and group rearing systems, and neither did the cost of producing 1 kg of weight gain (5150 Iraqi dinars for the individual system and 4763 dinars for the group system), it appeared from our results that the individual rearing system significantly improved feed intake and Dry matter intake compared with group rearing system, this due to may be individually raised lambs are less susceptible to stress resulting from social conflicts that occur between animals raised in groups, and this makes the animal more tranquil during feeding periods.Our findings contradicted those of [1] and [15], who did not observe any significant differences in dry matter intake between individual and group rearing systems.Concerning the effect of the physical form of the total mixed ration on feeding performance, the results indicated that there was no significant difference between the loose and pelleted ration forms in terms of feed intake (1130, 1168 gm/day respectively) and dry matter intake (1035, 1068 gm/day respectively ).Numerous previous studies demonstrated that pelleted diets significantly increased feed and dry matter consumption in comparison to loose diets [18][19][20][21].The process of compressing feed into pellet reduces the feed's volume and increases its density, resulting in a decrease in the rumen full and a subsequent increase in the amount of voluntary feed intake [20,22].In terms of the feed conversion ratio, the pelleted diet was superior to the loose diet (4.56, 5.99 respectively ), confirming the findings of [16] and [21], whereas [18,20], did not observe a significant difference between the pelleted diet and the loose diet, and it was mentioned [20], that pelletizing the feed does not always improve the feed conversion ratio.The pelleted diet was superior to the loose diet in terms of feeding efficiency (223, 172 gm weight gain / kg dry matter ), which may be attributable to the increased digestibility of nutrients as a result of pelleting the feed and the absence of energy losses during digestion [16].The percentage of dry matter intake relative to body weight did not differ substantially between the loose and pelleted diets (3.3% and 3.01%), our results did not agree with [19], what he found to be the percentage of dry matter intake relative to body weight significant differences between the loose and pelleted diets.The pelleted diet produced 1 kilogram of weight gain at a significantly lower cost (4,238 Iraqi dinars) than the loose diet (5,557 Iraqi dinars), this result agrees with [21] while [19], no significant difference was observed in the cost of producing 1 kg of weight gain between the loose and pelleted diets.The interaction between the rearing system and the physical form of the complete mixed ration revealed that the individual rearingpelleted form consumed significantly more feed per day (1,302 g/day) than the group rearing -pelleted form (1078 g/day) and the group rearing -loose form (1,108 g/day), but did not differ significantly from the overlap of the individual rearing -loose form (1,156 g/day).There were no significant differences in dry matter consumption across all interventions.Concerning the feed conversion ratio, the individual rearing -pelleted form (4.05) and the group rearing -pelleted form (4.89), respectively, had the highest values compared to the group rearing -loose form (5.38) and the individual rearingloose form (6.72).The highest feeding efficiency was observed in the individual rearing -pelleted form (247 gm gain weight / kg dry matter), compared to the group rearing -pelleted form (207 gm gain weight / kg dry matter) and the group rearing -loose form (188 gm gain / kg dry matter).None of the interactions revealed statistically significant differences in the proportion of dry matter intake relative to body weight.Individual breeding -pelleted form had the lowest cost for producing 1 kg of weight gain (3779 Iraqi dinars) compared to group rearing -pelleted form (4544 Iraqi dinars), group rearing -loose form (4983 Iraqi dinars), and individual rearing -loose form (6247 Iraqi dinars).According to the results of the interaction between the rearing system and the physical form of the total mixed ration, the best interaction appears to be individual rearing -pelleted form, which improves growth and nutritional performance while reducing the cost per kilogram of weight gain.

Conclusion
According to the results of the current research, although group confinement systems are more similar to the extensive or natural model, keeping lambs separately provides them with a greater chance to feed enough and subjects them to less stress due to social disagreements, making it the preferred option.Furthermore, pelleted total mixed ration may be used in place of loose total mixed ration when finishing off lambs.

Table 1 .
The experimental diet's components and their relative amounts.

Table 2 .
Chemical analysis of the experiment diet.
( 12 )ollowing equation was used to predict the amount of metabolizable energy( 12 ): ME(MJ/kg DM)= 0.31CP + 0.21EE + 0.4NFE Lambs were randomly distributed into four treatments.T 1 (group housing + loose diet) included 6 Lambs distributed in three group cages (2 Lambs /cage), T 2 (group housing + pellet diet) included 6 Lambs distributed in three group cages (2 Lambs /cage), T 3 (individual housing + loose diet) included 5 Lambs distributed in five individual cages (1 lamb / cage), and T 4 (individual housing + pellet diet) included 5 Lambs distributed in five individual cages.The duration of the actual experiment was 63 days.All lambs were fed ad-libitum to the Pelleted and loose total mixed ration, and the lambs in the 1 st treatment (group housing + loose diet) and the 3 rd treatment (individual housing + loose diet) were fed loose total mixed ration ad-libitum.The ewes in the 2 nd treatment (group housing + pelleted diet) and the 4 th treatment (individual housing + pelleted diet) were fed pelleted total mixed ration.A constant supply of water and mineral compounds were provided.

Table 3 .
Effect of Rearing System and Physical form of the Total Mixed Ration on Growth Performance of local male Lambs.

Table 4 .
Means in the same column with different letters differ (P<0.01).Effect of Rearing System and Physical form of the Total Mixed Ration on feeding Performance of local male Lambs.Means in the same column with different letters differ (P<0.01).