1Animal Resources Department, College of Agriculture, University of Salahaddin, Erbil, Kurdistan Region, Iraq.
kanyismail@yahoo.com
Received on 27/11/2014 and Accepted for Publication on 31/5/2015.
Effect of lambing interval on production characteristics in Kurdi local ewes of
Kurdistan region, Iraq
Salim Omar Raoof 1, Kanyaw Ismail Balisany1
ABSTRACT
The aim of this was to investigate the effects of lambing interval and some non- genetic factors (age of dam, season of lambing, sex of lamb, type of birth and ewes weight) on test day milk yield (TDM), total milk production (TMP), lactation period (LP), birth weight (BW) and weaning weight (WW).This study was carried out on200 local Kurdi ewes in Erbil plain, Kurdistan region during July, 2013 to July, 2014. The overall mean for the TDM, TMP, LP, BW and WW were 417.08 g, 47.35kg, 113.79 days, 3.68kg and31.25kg, respectively. Results revealed that lambing interval, age of dam, season of lambing, sex of lambsand type of birth significantly affected (p<0.05)TDM, TMP, BW and WW. The weight of dam had a significant effect (p<0.05) on BW and WW. Lambing interval was negatively correlated (P<0.01) with WW (-0.184). It was concluded that lambing interval, age of dam, season of lambing, sex of lambs and type of birth played a role in the variations of TDM, TMP, BW and WW in Kurdi ewes. The shorter the lambing interval the heavier the WW of lambs .It was also concluded that accelerated lambing is possible in Kurdijewe due to their non- seasonality. A three lambing during two years may be a preferable strategy to increase meat as well as milk from Kurdi local ewes.
Keywords: Kurdi ewes, lambing interval, milk production, birth and weaning weights.
INTRODUCTION
Ewes are one of the most important animals to many farmers in Kurdistan region of Iraq for its production of favorite milk and meat. The ewes are characterized with low reproductive performance as it has long lambing intervals due to many factors .Many authors reported that most breeds of sheep are sexually active during spring and early summer. The importance of ewe production as a source of animal protein has been increasing during recent years (Combellas et al., 1980).
Mating season of Kurdi ewes is naturally during pring and summer where the main sources of animal feeds are stubble and crop residues. The highest lambing rate is the biggest contributor to maximize profits from sheep farming (Aktas and Dogan, 2014).Karim (2004) in a field survey found that lambing rate, expressed as the number of lambs born per 100 adult ewes lambed, was 93.99.Accelerated lambing lead to the more efficient use of lambing facilities .Karim(2004) indicated that average percentage of accelerated lambing in Kurdi ewes was 24.08 % and that fertility defined as ewes lambed out of ewes exposed to rams was 89.3 %. Furthermore, he reported that ewes lambed at less than 1 year was 35.67%.
lambing, sex of lamb, type of birth and ewe's weight on milk traits and weights of birth and weaning.
MATERIALS AND METHODS
The data used in this study were obtained from200 Kurdilocal ewes aged from 2 to ≥ 5years in Erbil plain of Kurdistan region in Iraq, during July, 2013 to July, 2014.Lambs were separated from their dams overnight prior to milking. Milk yield was recorded at monthly interval starting from the a month after lambing till the ewes were dried off (when milk yield was less than 100 gm) as recommended by International Committee for Animal Recording (ICAR , 1995). Lactation period was recorded from first test day till drying off of ewes. Actual lactation period (LP) is equal to the figures written in table (1) plus thirty days.
Ewes were milked by hand and the quantity of morning milk obtained multiplied by 2 to estimate test day milk yield (daily milk yield, TDM).Monthly milk yield was calculated by multiply TDM by 30. Total milk yield (TMP) was calculated by summing monthly milk yield. Ewes were allowed to graze wheat and barley residues for 8 hours (from 9 am to 5 pm) with one hour rest (13:00 pm to 14:00 pm), with a supplement of 500g concentrate diet composed of barley grain and provided twice daily in the morning and evening. Straw and Alfalfa (green fodder) were offered ad libitum. Birth (BW) and weaning weights(WW) for each lamb were recorded. Lambs were weighed by hanging balance (100 gm sensitivity).Lambs suckled their dams till weaning and an additional 100 g of concentrate per head was offered during suckling period. Animals were vaccinated against common disease.
For the statistical analysis, calendar year was divided into 3 seasons of calving. These were season 1 (November-January), season 2 (February –April) and season 3(May - July). Lambing intervals were divided
into short (240 – 270 days), medium (271– 300 days) and long ( ≥301 days).Age of ewes was classified into 2, 3, 4, and ≥5years old. Ewe's weights were cross classified into less than 50,50-60and more than 60kg.
The collected data were analyzed using general linear Model(SAS, 2005) to estimate the independent variables. Duncan multiple range test (Duncan, 1955) was performed for the mean differences comparisons. Thefollowing linear model was applied.
Yijklmno = µ +Li +Aj +Sek +Sl +Tm+Wn + eijklmno
Yijklmno: is the dependent variables of each trait
studied (TDM, TMP, LP, BW and WW). µ: Overall mean
Li: Effect of ith lambing interval; i = short 240-270,
medium 271-300 and long lambing interval≥301days. Aj:Effect of jth age of dam; j = 2, 3, 4 and≥5years old.
Sek::Effect of kth season of lambing; k =
November-January, February-April and May -July.
Sl: Effect of lthsex;l=l for male and 2 for female.
Tm: Effect ofmthtype of birth; m=1 for single and2 for
twin.
Wn: Effect of nthewe's weight; n= Less than
50,50-60and more than 60kg
eijklmno :Random error associated with the ijklmoth
observation, assumed to be . ) 0 ,Ə2e ( NID~
The coefficients of correlation among traits were estimated using SAS program(SAS, 2005).
RESULTS AND DISCUSSION Milk production
intervals were 414.94, 448.47 and 372.31days, respectively. The corresponding figures for TMP were 47.27, 50.92 and 42.08kg,respectively.The result also revealed that no significant effect of lambing interval on lactation period. These findings were in agreement with those reported by Folman etal. (1966).
Young as well as old ewes produced less milk than those aged 3or4 years. Results of the study had shown that the age of ewe at lambing significantly affected test day milk yield, which were378.57, 456.92, 439.47 and 388.41g for ewes aged 2, 3, 4and ≥5years, respectively. These results were due to undeveloped of udder growth of young ewes and due to not effectively utilize feed of more than 5 years. Also the cause of high milk production with advanced age till 5 year old might due to the development of the udder responsible for milk production. It might be also accompanied by an increase in gut size and thus increase feed intake, which is reflected positively on milk production. These results were in agreement with Abd-Al-Noor (2011) and Raoofet al.,(2013).Season of lambing had a significant effect on test day milk yield and total milk production. The findings were in agreement with those data reported byRaoof, (2009) and Abd-Allahet al., (2011).
Ewes lambed during February –Apriland May- July produced more total milk (50.76 and 49.93 kg, respectively)than those lambed during November. – January. (42.86 kg)(Table 1). This result may be due to differences in availability of feed during grazing. Table (1) shows that ewes suckled by male lambs tend to produce more test day milk yield (456.58g) than those suckled by female lambs(413.50g). This may attributed to the fact that males are usually bigger than females and need higher nutrients, thus induce mothers to produce more quantities of milk. On the other hand, Raoof et al.,(2013) indicated a non-significant effect of sex of lamb on milk production .Ewes lambed twin were
significantly had more test day milk yield (447.73g) than those lambed single(408.89g). Moreover, total milk production from ewes lambed twin had more (54.08kg)than that lambed single(47.94kg). Similar result was found by Hussain et al., (2013), who reported that ewes suckling twins was consistently produced higher daily milk and total milk than those suckling single lamb. The result of this study revealed that total milk estimated from ewes with twins was 44 % higher than those produced by ewes with single lambs. The result of this study was in agreement withRaoofet al.,(2013) whose stated that type of birth had a significant effect(p<0.05) on test day milk yield. Ewes that lambed twin excelled in the production of milk (592.19 g) compared to those lambed single (506.49 g).
Birth and Weaning Weights.
results may be explained by the fact that young ewes that had not reached mature adult size continue to grow during gestation and thus compete with the fetus for available nutrients. This response was well documented (Macedo and Hummel, 2006).Furthermore, Aktas and Dogan (2014) indicated that ewes aged 2 years lambed lighter at birth than ewes aged more than 5 years. Ewes aged 2 years lambed lower weight at birth than the average, and this weight has increased gradually to reach a maximum at age 3-4 years. These results were agreed with Al-Juwari (2011) and Raoof et al., (2013). The reason is due to increase in the uterus size with advancing age of the ewe, so that it can create better uterine environment for the growth of the fetus, also more feed amount available for fetal growth and development. On the other hand, Al-Dabbagh and Ahmed(2001) and Al-Jalily et al., (2006) showed no significant effect of age of ewes on weaning weight but had a significant effect on birth weight. The season of lambing had a significant effect (P<0.05) on BW and WW. Ewes lambed during February – January and May – July had higher BW and WW.BW recorded in this study were, 3.42, 3.82 and 3.83 kg for ewes lambed during, February – January, May – July and November - January, respectively. The corresponding figures for WW were 29.99, 31.73 and 32.09 kg, respectively. These findings are in agreement with those found by Bermejo et al., (2010),who showed that season of the year affected significantly BW and WW probably because lambs had access of feed during this months. Ewe's weight significantly affected (P<0.05) birth weight and weaning weight(Table 2).Results obtained by Hussain et al., (2013) were in agreement with our findings, which showed that the weight of lambs being greater as ewe's weight increased because birth weight and weaning weight had a linear relationship. Weight of ewes between 50-60 kg had highest birth weight
(4.41kg) and weaning weigh (33.77kg). This may be due to ewes with such weights were supplying their fetus quantities of feed during better than those with less or higher weights. Also large-sized ewes characterized by the expansion of the size of her uterus, which provides a wider space for growth and development of the fetus. This result agreed with the findings of Al-Jalily et al., (2006).It is well documented that heavier BW of lamb, reached more WW. As well as lambs with heavier weight at birth increase the vitality and strength of the lambs and enabling lambs to intake large amounts of milk during lactation.
Correlation coefficients
Table (3) shows that lambing interval was negatively correlated (P<0.01) with WW (-0.184). This indicated that the shorter the lambing interval the heavier the WW of lambs. However, all other correlation coefficients between lambing intervals with other variables studied were not significant. BW was significantly correlated (P<0.01) with WW (0.637).Furthermore, age of dam was significantly (P<0.01) correlated with BW. Nevertheless, no significant correlation coefficients were found between milk traits and other variables studied.
CONCLUSION
and exhibit estrus almost the whole year round.
The results suggested that accelerated lambing is possible in Kurdi ewe due to their non seasonality. A three lambing during two years may be preferable strategy to increase meat as well as milk from Kurdi
local ewes. The advantages have to be weighed against the price of extra feed. Such strategy may accelerate genetic improvement of the Kurdiewe through increase number of lambs born and this will increase intensity of selection of both males and females.
Table 1. Least squares means ± stander error of lambing interval and other independent factors affecting milk production.
Factor No. Test day milk yield(g) Total Milk Production(kg) Lactation Period(day) +
Overall mean 200 417.08±1.44 47.35±0.17 113.79±0.06
Lambing interval (days): Short: 240-270 Medium: 271-300 Long: ≥301 76 59 65 * 414.94 ± 1.45b 448.47± 1.30a 372.31± 1.39c * 47.27±0.16a 50.92±0.14a 42.08±0.15b N.S 114.16±0.05a 113.72±0.04a 113.46±0.06a Age of Dam(years): 2 3 4 ≥5 49 45 64 42 * 378.57± 2.27b 456.92 ±1.83a 439.47±1.99a 388.41±1.55b * 43.26±0.26b 51.34± 0.21a 49.75±0.22a 44.53±0.17b N.S 114.49± 0.01a 112.31±0.01a 113.51±0.06a 114.93±0.06a Season of lambing: November.-January. February.-April. May-July 68 75 57 * 380.10±0.99b 445.56±1.41a 437.50±1.36a * 42.86±0.11b 50.76±0.16a 49.93±0.18a N.S 113.32±0.04a 114.11±0.04a 114.13±0.08a Sex of lamb: Male Female 109 91 * 456.58±1.22a 413.50±1.57b * 55.78± 0.12a 48.60±0.14b N.S 117.82±0.03a 120.92 ± 0. 06a Type ofbirth: Single Twin 134 66 * 408.89± 0.83b 447.73±1.24a * 47.94±0.11b 54.08± 0.27a N.S 117.41±0.10a 120.46±0.23a
* Means within a particular category with different letters are significantly different (P<0.05). N.S means Non Significant
Table 2. least square means ± stander error of lambing interval and non-genetic factors affecting birth and weaning weights.
Factors No. Birth weight (kg) Weaning weight (kg) Age at weaning (days)
Overall mean 200 3.68±0.02 31.25±0.03 93.3±0.01 Lambing Interval(day) 240-270 271-300 ≥301 76 59 65 * 3.57± 0.03b 3.90 ± 0.01a 3.97 ± 0.02a * 32.60±0.08a 31.26±0.06b 29.76±0.09b N.S 93.8 ±0.01a 92.9± 0.01a 93.0± 0.01a
Age of Dam (year) 2 3 4 ≥5 49 45 64 42 * 3.57± 0.03b 3.90 ± 0.01a 3.97 ± 0.02a 3.23± 0.01b * 29.58 ± 0.14b 33.00 ±0.06a 32.53 ±0.10a 28.96 ±0.11b N.S 91.2 ±0.01a 96.7 ±0.01a 93.7±0.01a 93.3±0.01a Season November.-January. February.-April May –July 68 75 57 * 3.42±0.01b 3.82±0.01a 3.83±0.01a * 29.99±0.08b 31.73.±0.06a 32.09±0.10 a N.S 93.2±0.01a 93.2±0.01a 94.2±0.02a Ewes weight(kg) Less than 50 50-60 more than 60 60 93 47 * 3.20±0.01c 4.41±0.02a 3.62± 0.01b * 28.57±0.09c 33.77±0.08a 31.71±0.05b N.S 92.3±0.01a 92.1±0.01a 94.4±0.01a
* Means within a particular category with different letters are significantly different (P<0.05). N.S means Non Significant
Table 3. Correlation Coefficients of the studied traits. Lambing
interval Birth weight
Weaning weight
Test day milk yield
Birth weight 0.019
Weaning Weight -0.184** 0.637**
Test day milk yield -0.115 0.121 0.089
Age of dam 0.058 -0.185** -0.113 -0.167
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