Резюме. This study was investigated to comparative performance and digestibility of nutrients in Afshari and Ghezel ram lambs. In the first trial 30 animals at the age of 5 months (15 Afshari (AF) and 15 Ghezel (GH) ram lambs were randomly allocated to individual pen, in order to determined fattening performance for a period of 90 days. In the second trial 10 animals at the age of 10 months from each ecotype were randomly allocated in individual metabolic cages to determine the in vivo digestibility for 8 days after adaptation period. Data were analyzed in a complete randomized design using the GLM of SAS and the means were compared with Duncan’s multiple range test. The results showed that there wasno significant effect in initial body weight, daily gain, feed conversion ratio and feed efficiency between treatments. Ghezel ram lambs had lower feed intake compared to Afshari ram lambs. The study showed that there were no significant differences for digestibility of DM, protein, EE, ADF, NDF and P, Ca, Mg, Fe and Cu between treatments. In conclusion the results showed that GH had no significance effect on feed digestibility and fattening characteristics of cross breed lambs.

Ключови думи: ram lambs; Afshari; Ghezel; fattening performance; digestibility

Introduction

There are high variations among different Iranian sheep breeds in terms of carcass yield and prolificacy. Twin births are frequent in some breeds though infertility is rarely observed in these flocks. The Ghezel sheep originated in northwestern Iran and northeastern Turkey. This region in Iran is known as Azarbayjan and is typlified by dry, cold mountain weather. The fleece of this sheep is red and have sections of black red or light red. The Ghezel are used for both meat and wool in this region (Tavakkolian, 2000). The productivity of livestock affected by genetic and environmental factor such as diet. The higher productivity breed usually followed by higher nutrient requirement such as protein which is needed for tissue deposition (Yulistiani et al.,2015). Therefore, the objective of this study was to evaluate comparative performance and digestibility of nutrients in Afshari and Ghezel ram lambs.

Materials and methods

In order to determination of fattening performance the data of 30 Afshari and Ghezel lambs which born between 2016 and 2017 were used. In vivo feed digestibility was assigned with 6 Afshari and Ghezel ram lambs respectively. The research carried out in research flock at Shooli sheep breeding station in Shahrekord. The flock was generally kept from March to June at the station.

Chemical composition

Ingredients of diets were analyzed according to AOAC (2000) methods. Dry matter (DM) with putting feed in 100°C for 24 h., method 967.03, ash by incineration in 550°C for 8 h; method 942 and crud protein (CP) by Kjeldahl procedure. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were analyzed according to two stage procedures described by (Stern et al., 1997; Van Soest, 1994).

First study

At the first study 30 ram lambs at the age of 10 months (15 Afshari and 15 Ghezel ram lambs) were randomly allocated to the experimental design for 90 days’ period to study fattening performance in a same condition. The aim of the study was to evaluate the performance of Afshari and Ghezel ram lambs. In current study the lambs were fed by 3 times per day in the 24 individual pens. The experimental diet is shown on Table 1. In this study the initial weight (IW), final weight (FW), feed intake dry matter (FI), average daily gain (ADG), feed conversion ratio (FCR) and feed efficiency (FE) were investigated.

Second study

At the second study for investigation the in vivo digestibility of feed ingredients, 10 adult animals (5 Afshari and 5 Ghezel ram lambs) with initial weight 52± 5 kg and average age of 300 days were randomly allocated to the individual metabolic cages for 2 weeks. They also fed by maintenance requirement with total mixed ration (TMR) contained 60 % alfalfa hay and 40% feedlot concentrate at level, 0.87±0.05 kg day-1 (Ensminger & Parker, 1986). The ingredients and chemical composition of the experimental rations are shown in Table 1. The diets were fed seven days for adaptation and seven days for experimental period. Also due the trial plan their feed intake, residual feed and feces were collected and digestibility of diets and nutrients were investigated (Givens et al., 2000).

Statistical analysis

The model used in this study is: Yij = µ + Ti + eij where Yij is the individual observation, µ is the overall mean, Ti is the effect of treatment and eij is the remainder effect.

Data were analyzed in a completely randomized design using the GLM of (SAS, 2001), the means were compared with Duncan’s multiple range test.

Result

Data showed that although initial live weight for AF was higher than GH. Data showed that final body weight gain and average daily gain for AF lambs were higher than GH lambs too (Table 2).

There was a significant difference for feed intake among treatments and feed conversation ratio was better for AF lambs. There is no significant difference between experimental lambs about feed efficiency.

As data observed from Table 3, average nutrients consumption such as total feed intake, dry matter intake and protein intake were higher for Afshari ram lambs and the intake of ether extract, Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were higher for Ghezel ram lambs. But there were no significant differences between treatments.

According to lambs feed consumptions, phosphorus, calcium and magnesium (4.2,21.8 g and 10.4 ppm) were more consumed and zinc, cooper and iron (34.1, 1.03and 218 ppm) were more consumed for Afshari and Ghezel ram lambs respectively.

Data from Table 5 showed that among fecal nutrient elements, fecal dry matter, protein, ethyl extract, neutral detergent fiber and acid detergent fiber were higher for AF ram lambs. These data showed that digestibility of these nutrient elements was lower on AF ram lambs.

Fecal phosphorus, calcium, magnesium, zinc, cooper and iron (1.9 gr, 10.6 gr and 4.9 ppm, 28.7ppm, 14.7ppm,124.5ppm) were higher in LB compared to R ×LB lambs (1.7 gr, 9.7 gr and 4.3 ppm, 24.9ppm, 11.9ppm,109.1ppm) respectively.

The means of in vivo digestibility coefficients of nutrients on AF and GH ram lambs are shown in Table 7. Although there were no significant differences about nutrients digestibility between breeds but also nutrients digestibility was higher on GH lambs. These data showed that acid detergent fiber digestibility with in vivo method was higher for AF groups.

As result relevant by Table 8, the means of in vivo digestibility coefficients of minerals was affected none significantly by animal breeds. Data showed that digestibility of phosphorus, calcium, magnesium, zinc, cooper and iron were more on R× LB ram lambs.

Discussion

Contrary to our finding, (El Fadili et al., 2001) found a significant difference for fattening average daily gain between pure bred and cross bred lambs, in favor of cross breeds. Khaldari et al (2007) reported that there was no significant difference between final and slaughter weight of pure bred and crossbred lambs. Although overweight LB lambs according to their high feed intake, but no increase in feed efficiency lead to increasing the production costs, hence changes in the efficiency of feed utilization in LB lambs cross breeding program is highly regarded (Kazemi et al., 2014). Abdullah et al. (2010) indicate that crossbreeding Awassi with exotic breeds improves growth rate and meat production. In this study, there are no significantly differences about feed conversion ratio and feed efficiency between R ×LB cross breeds and Lori Bakhtiari pure breeds. Galivan (1996) showed that the average daily gains after weaning and during the finishing period and dry matter intake in breeding programs are important.

Talebi (2012) demonstrated that with increasing feed efficiency and increased daily weight gain of fattening lambs lead to reduce the fattening period and achieve the ideal faster weight. No significant difference in feed conversion between cross breeds and pure breeds was expressed earlier (Gokdal et al., 2004). The result of this study are in agreement with (Sayili et al., 2009) demonstrated that lower weight at the start of the fattening period could improve feed efficiency in fattening ram lambs. In the present study there were no significant differences for mineral intake and uptake on AF and GH ram lambs and it was due the lack of significant differences in their feed intake.

Esmailizadeh et al (2011) showed that dry matter intake was significantly influenced by lamb’s genotype at different recording periods, except at the fourth one, and total period of the experiment (P≤0.0 5). Manafi Azar et al. (2005) and Kiyanzad et al. (2003) conducted a feedlot trial involving three Iranian local breeds of sheep (Chaal, Zandi and Zel) and reported that lamb’s genotype had no significant effect on average daily gain during a 114day feedlot period. Although our studies on feed digestibility showed that no significant differences for dry matter, protein, fat, fiber, macro and micro elements but also the better digestibility of attributes mentioned above had shown for R ×LB cross breeds ram lambs (Table 8). It seems that R ×LB cross breed lambs have better ability to adsorption nutrients from the same diet compared to LB pure breeds.

Result of this study in agreement with (Esmailizadeh et al, 2012) that showed there were no significant differences between pure lambs and cross breeds ones about the feed conversion rate. According to the limitation of feed and natural resources and for as much as production efficiency of meat animals can be defined as the return of salable product per unit of feed input, therefore, any reduction in feed cost would have a tremendous effect on production efficiency (Sidwell et al., 1964; Timon, 1986; Lewis & Emmans, 2010), since the Romanov × Lori Bakhtiari ram lambs had lesser feed intake and better feed efficiency there are more advantageous for farmers. The positive effects of cross breeding for lambs on better performance of lambs had demonstrated formerly by (Donald et al., 1963). Although (Singh et al., 1967) showed that in some cases cross breeding may decrease the performance of the lambs such as the birth or weaning weight, but the better daily growth rate, better feed efficiency and lesser mortality would be desirable.

Conclusion

We may mention that the existence of breed’s differences for daily dry matter intake and digestibility of dry nutrients. We could be explained some benefit acts by using Afshari breed ram lambs on performance and digestibility of nutrients and minerals. Also further tests are needed to explore and more detail explanation.

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