Refeeding ewe’s ad libitum after energy restriction during mid-pregnancy does not affect lamb feed conversion ratio, animal performance and meat quality

Journal Pre-proof Refeeding ewe’s ad libitum after energy restriction during mid-pregnancy does not affect lamb feed conversion ratio, animal performance and meat quality Santiago Luzardo, Guillermo de Souza, Graciela Quintans, Georgett Banchero

PII:

S0921-4488(18)30952-0

DOI:

https://doi.org/10.1016/j.smallrumres.2019.09.020

Reference:

RUMIN 5996

To appear in:

Small Ruminant Research

Received Date:

25 October 2018

Revised Date:

18 September 2019

Accepted Date:

25 September 2019

Please cite this article as: Luzardo S, de Souza G, Quintans G, Banchero G, Refeeding ewe’s ad libitum after energy restriction during mid-pregnancy does not affect lamb feed conversion ratio, animal performance and meat quality, Small Ruminant Research (2019), doi: https://doi.org/10.1016/j.smallrumres.2019.09.020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier.

Refeeding ewe’s ad libitum after energy restriction during mid-pregnancy does not affect lamb feed conversion ratio, animal performance and meat quality.

Santiago Luzardoa*, Guillermo de Souzaa, Graciela Quintansb, Georgett Bancheroc.

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Instituto Nacional de Investigación Agropecuaria, Ruta 8, km.282, Treinta y Tres, Uruguay.

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Instituto Nacional de Investigación Agropecuaria, Ruta 5, km.386, Tacuarembó, Uruguay.

Instituto Nacional de Investigación Agropecuaria, Ruta 50, km.11, Colonia, Uruguay.

*

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Corresponding author: Santiago Luzardo. E-mail: [email protected].

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Highlights

Dams´ dietary treatment and litter size have no effect on lambs’ milk intake

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Lambs’ milk feed conversion ratio does not differ due to dams´ dietary restriction

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Weaning weight is not affected by ewes’ feeding treatments or lamb sex

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Lamb hot carcass weight and yield are not affected by ewes’ dietary restriction

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Lamb meat shear force do not differ by dams’ dietary treatment

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

Abstract

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The aim of the study was to evaluate maternal energy restriction in ewes from day 48

to 106 of gestation on pre- and post-weaning lambs` performance, carcass and meat quality when their dams were fed ad libitum after the restriction period. Ewes bearing single or twin lambs were assigned to two dietary treatments from day 48 to day 106 of gestation: restricted (R) at 60% of their metabolizable energy (ME) requirements, or non-restricted (NR) at 100% of their ME requirements. After the restriction period ewes grazed all together ad libitum until

weaning. Subsequently, male lambs were placed in a feedlot until slaughter. Ewes body weight was recorded during nutritional treatment application and at weaning. Litter size and lamb sex were recorded, and feed intake and body weight were measured from birth until slaughter. After slaughter, carcass weight and yield, subcutaneous tissue depth (GR site), carcass (CL) and leg length (LL), frenched rack (FR) and leg weights were determined. After 5 days of meat aging, color parameters and Warner-Bratzler shear force were determined on longissimus lumborum muscle. Non-restricted ewes weighed 7.5 kg more than R ewes (P <

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0.05) at the end of the restriction period. Lamb birth weight (BW) was no affected (P > 0.05) by dams’ treatment although male and single lambs had a greater (P < 0.05) BW than females and twins, respectively. No significant differences (P > 0.05) were detected on the weaning

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weight between ewes’ feeding treatments or lamb sex. Estimated average milk intake by

lambs were not affected (P > 0.05) by dams´ treatments and litter size. Lambs born to R or

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NR ewes did not differ (P > 0.05) in feed conversion ratio (FCR) of milk, while twins were

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more efficient (P < 0.05) than single-born. Male lambs from R and NR ewes did not differ (P > 0.05) in weaning and final weight, feed intake and FCR during the fattening phase. Slaughter and hot carcass weight, CYd, GR, CL and LL were not affected (P > 0.05) by

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treatment and litter size. Brightness of meat (L* value) was greater (P < 0.05) in lambs from R ewes than NR. Ewes restricted at 60% of their ME requirements in mid-gestation seems to

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have the capacity to compensate any detrimental effects on lamb growth and development if

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adequate refeeding conditions are provided in late gestation and throughout lactation.

Keywords: fetal programming, lamb, dietary restriction, growth, meat quality.

Introduction

Extensive sheep production systems in Uruguay determine some extent of nutritional restriction on ewes during gestation due to low quality and availability of native grassland in winter (Bermúdez and Ayala, 2005). Wu et al. (2006) stated that alterations in fetal nutrition and endocrine status may result in developmental adaptations that permanently change the structure, physiology, metabolism, and postnatal growth of the newborn. Adequate maternal nutrition provides nutrients needed for myogenic cell proliferation and thus muscle fiber formation (Du et al.,

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2017). Prenatal maternal nutritional restriction during the time of muscle differentiation demonstrated an increase in type IIB muscle fibers and in intramuscular fat; although

significant effects on subsequent lamb carcass quality could be relatively small (Daniel et al.,

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2007). In fact, undernourished ewes during early- or mid-gestation have no major detrimental major effect on lamb carcass, meat tenderness and muscle fiber characteristics (Nordby et al.,

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1987; Piaggio et al., 2018). However, maternal nutrient restriction in late gestation has a great

(Taplin and Everitt, 1964).

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adverse effect on postnatal growth due to retarded placental development and fetal growth

Although the placental nutrient transfer capacity is responsive to environmental

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stimuli, it can adapt to help maintain the fetal nutrient supply, particularly when the placenta is small (Fowden et al., 2006).Therefore, the minor effect of ewe nutrition restriction during

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early and mid-gestation on lamb performance could be explained by an in-utero compensation

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during the last third of gestation and/or during lactation when ewes are refed ad libitum (Krausgrill et al., 1999; Piaggio et al. 2018). To understand the magnitude of these findings, we evaluated postnatal lamb

performance during lactation and fattening periods measuring intake and feed conversion ratio of milk and total mixed ration. Our hypothesis was that lambs born to ewes submitted to energy restriction from day 48 to 106 of gestation will not have adverse effect on pre- and

post-weaning lambs` performance, carcass and meat quality when their dams are fed ad libitum after the restriction period. Material and methods Location and experimental treatments The experiment was carried out at the Experimental Unit “La Estanzuela” of INIA, Uruguay (35° S). The experimental procedures were approved by the Committee for Animal Ethics of INIA, number 2016.48. Adult Polwarth ewes (multiparous and 4-year-old) were

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heat-synchronized by using a double dose of 160 mg d-Cloprostenol (Veteglan Laboratorio Calier, Barcelona, Spain) and collectively mated in the second heat after synchronization

using 6 Finnish rams/100 ewes. One hundred and fourteen ewes (44.2 ± 4.9 kg BW), bearing

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single (n = 75) or twin lambs (n = 39) were assigned to two treatments from day 48 to day 106 of gestation: R, ewes were offered a total mixed ration (TMR) (871.6 g DM/kg; 145.7 g

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CP/kg dry matter (DM); 212.0 g ADF/kg DM, 344.8 g NDF/kg DM and 2.65 Mcal ME/kg DM), which supplied 60% of their metabolizable energy (ME) requirements, and NR, ewes

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were offered the same TMR supplying 100% of their ME requirements (Graz Feed™, 2010). During the application of the treatments, ewes were fed in uncovered collective pens, with an

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area of 30m2/ewe. From day 107 of pregnancy to 10 days before the expecting time of lambing, ewes grazed oat grass (allowance 1800 kg DM/ha; 158.6 g CP/kg DM, 354.0 g

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ADF/kg DM and 531.5 g NDF/kg DM and 2.37 Mcal ME/kg DM) ad libitum (daily

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allowance: >12 kg DM/100 kg of live weight) and during the last ten days ewes also received a supplement of 0.2 kg DM of barley grain per ewe (895.7 g DM/kg; 117.5 g CP/kg (DM); 91.3 g ADF/kg DM, 27.8 g NDF/kg DM and 3.12 Mcal ME/kg DM). During lactation, all ewes grazed together on improved pastures, and lambs were weaned at average age of 132 days. Ewes were weighed every 14 days from onset of nutritional treatments until lambing. Lamb management and measurements

At birth, lambs were identified with an ear tag, weighed (BW) and their sex was recorded. Lambs were then weighed every 14 days until slaughter. Milk consumption was estimated through milking the dams every 14 days. For mill extraction, early in the morning the ewes were brought from the pasture and their lambs were removed, weighed and kept in a yard with dry food and water ad libitum. The ewes were hand milked after an injection of 1 UI of oxytocin intramuscular and milk was discarded. Time of milking for each ewe was recorded. Ewes could return to the pasture and about 4 h later they were milked again under

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the same procedure. After recording individual ewe´s milking time, milk was weighed, and a sample was kept for chemical analysis. Lambs were returned to their mothers after milking. Milk production was calculated using the weight of milk obtained in the second milking

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divided by the minutes between both milking and then extrapolated to a 24 hours production (Doney et al., 1979).

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After weaning, fifty-five male lambs (24 lambs from R ewes and 31 from NR ewes; 28

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single lambs and 27 twins) were allocated to individual pens (5 m2/lamb) and fed ad libitum a finishing TMR, containing 893.4 g DM/kg, 187.9 g CP/kg DM, 275.5 g ADF/kg DM, 396.3 g NDF/kg DM and 2.49 Mcal ME/kg DM until slaughter. During an adaptation period of 15

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days, lambs were fed alfalfa hay (934.3 g DM/kg, 175.6 g CP/kg DM, 302.0 g ADF/kg DM, 426.7 g NDF/kg DM and 2.52 Mcal ME/kg DM and increasing TMR levels until reaching

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1.335 kg total feed allowance, starting with 0.445 kg TMR/lamb and gradually increasing this

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volume up to 1.335 kg. Total mixed ration allowance was managed to 10% feed refusal and was offered in three meals (0800, 1200 and 1600 h). Feed refusal was measured daily before adding the morning meal to estimate feed intake. Carcass and meat measurements At the average age of 190 days, lambs were humanely slaughtered in a commercial meat packing plant according to the Uruguayan legislation. Live weight at slaughter (SW), hot

carcass weight (HCW) and carcass yield (CYd) were determined. After slaughter, carcasses were kept in a cooler for 24 h at 2-3ºC. Subsequently, carcass (CL) and leg length (LL), and total tissue depth over the 12th rib at 11 cm from the midline of the carcass (GR) were measured and then carcasses were deboned. At the deboning room, right and left frenched racks and legs (boneless, chump-on) were weighed and samples of the longissimus lumborum muscle were removed from the left half-carcass which were vacuum packaged and transported to the meat laboratory of INIA to achieve 5 days ageing under refrigerated

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conditions (0-2ºC). After ageing, instrumental lean color (CIE L*: lightness, a*: redness and b*: yellowness) was measured on each sample in triplicate with a Minolta chromameter CR400 (Konica Minolta Sensing Inc., Japan) using a C illuminant, a 2º standard observer angle

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and 8 mm aperture size and calibrated with a white tile before use. Furthermore, WarnerBratzler shear force (WBSF; model D2000- WB, G‐ R Electric Manufacturing Co,

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Manhattan, KS) was assessed according to the American Meat Science Association guidelines

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(2016). Loins were cooked in a preheated clam shell style grill (GRP100 The Next Grilleration, Spectrum Brands, Inc., Miami, FL) until the internal temperature reached 71ºC. After cooking, six cores (1.27 cm diameter) were removed from each meat sample parallel to

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the longitudinal orientation of muscle fibers. Individual shear force (SF) values were averaged to assign a mean peak WBSF value to each sample.

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Statistical analysis

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Response variables until weaning were analyzed as a 2 x 2 x 2 factorial design with treatment (R or NR), sex (male or female), litter size (single or twin) as fixed effects and the random effect of replicate using the PROC MIXED procedure of the Statistical Analysis System software (SAS Institute, Cary, NC, version 9.4). Ewes and lambs body weight were analyzed as repeated measures and the unstructured (UN) and autoregressive (AR [1]) covariance structures were used based on the Akaike Information Criterion, respectively.

After weaning, only male lambs were fattened until slaughter and therefore the factors evaluated were treatment and litter size. Slaughter weight (SW) was used as a covariate to analyze hot carcass weight (HCW) and HCW was used as a covariate to analyze carcass traits. Studentized residuals plots were evaluated to test homogeneity of variance and normality for all data. Kenward-Roger approximation was used to calculate denominator degrees of freedom for different covariance structures for adjustment of the F-statistic. After ANOVA, least squares means were calculated for treatment comparisons with a significance level of α =

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0.05, using the PDIFF option of LSMEANS, when F-tests were significant (P < 0.05). Results

Regarding to ewe’s performance, no differences (P > 0.05) were observed in the body

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weight at the beginning of the nutritional restriction period but NR ewes weighed 7.5 kg more (P < 0.05) than R ewes at the end of the restriction period (Table 1). As expected, ewes

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bearing twins presented a greater (P < 0.05) body weight at the beginning and end of the

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dietary treatment period than ewes gestating single lambs (Table 1). Energy restriction imposed to ewes during gestation did not affect (P > 0.05) birth weight (BW) while male and single lambs had a greater (P < 0.05) BW than females and

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twins, respectively (Table 2). No significant differences (P > 0.05) were observed on the weaning weight (WW) between ewes’ feeding treatments or the sex of the lambs. However,

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WW of single lambs was 22% greater (P < 0.05) than twins. In the same way, pre-weaning

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average daily gain (ADG) in lambs was not influenced (P > 0.05) by dietary treatments in ewes or the sex of the offspring, but single lambs grew faster (P < 0.05) than twins (Table 2). Estimated average milk intake and total solids by lambs were not affected (P > 0.05) by dams´ treatments and litter size. Feed conversion ratio (FCR; intake per kilogram of weight gain) of milk was not different (P > 0.05) between lambs born to R or NR ewes, while twins were more efficient (P < 0.05) than single-born lambs (Table 2).

After weaning and during the fattening phase, male lambs from R and NR ewes did not differ in terms of WW (in this case is the initial weight), final weight (FW) and ADG. Nevertheless, single-born lambs had a greater (P < 0.05) WW and FW than twins (Table 3). Maternal nutrition during mid-gestation did not affect (P > 0.05) the feed intake of lambs during the fattening phase and no differences (P > 0.05) were found between single and twins-born lambs. Lambs from R and NR ewes did not show significant differences (P > 0.05) in FCR during fattening, while twins were more efficient (P < 0.05) converting feed into

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weight gain than single lambs (Table 3). Dietary energy restriction in ewes had no effect (P > 0.05) on SW although singleborn lambs were heavier (P < 0.05) than twins. Hot carcass weight, CYd, GR, CL and LL

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were not affected (P > 0.05) by treatment and litter size. Frenched rack weight and yield were greater (P < 0.05) in lambs born from NR ewes than those from R (Table 4). Meat quality

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characteristics were mostly not affected (P > 0.05) by treatments, except the L* parameter of

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lean color which was greater (P < 0.05) in lambs from R ewes than NR. In addition, singleborn lambs presented an increased (P < 0.05) b* value than twins (Table 4). Discussion

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The current study evaluated the effect of restricted maternal nutrition during midgestation followed by ad libitum refeeding phase during late gestation and lactation on growth

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parameters, feed efficiency, carcass traits and meat quality of lambs.

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Ewe feeding treatment during mid-gestation did not affect lamb birth weight which is in accordance to the findings reported by Ford et al. (2007) where ewes fed at 50% of estimated nutrient requirements from day 28 to 78 of pregnancy produced lambs without significant difference in birth weight compared to the control group. In the same way, Piaggio et al. (2018) did not observe differences in birth weight in lambs of ewes with energy restriction of 40% of their ME requirements from day 45 to 115 of gestation. Roca Fraga et al.

(2018) in a meta-analysis study reported that maternal feeding restriction in early- and midpregnancy had only a small and non-significant effect on lamb birth weight but latepregnancy undernutrition and long-term dietary restriction extending to late-pregnancy were associated with a decrease of up to 22% in lamb birth weight. Taplin and Everitt (1964) stated that retarded placental development and fetal growth before 90 days of gestation, due to maternal undernutrition, may be partially compensated by a high feeding regime from day 90 of gestation to lambing. These authors stated that this compensatory effect could be impaired

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if ewes´ underfeeding conditions last beyond 90 days of pregnancy. In our study, refeeding conditions took place after 106 days of gestation, but it seems that there was still enough time to compensate growth since there was no effect on BW due to feeding restriction. Everitt

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(1967) did not observed differences in BW between male and female lambs but male lambs were heavier at weaning than females. Conversely to those findings, in the present study, male

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lambs were heavier at birth than females in agreement with the results reported by Daniel et

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al. (2007) and no differences in WW were detected between lambs from both sexes. Villette and Theriez (1981) reported a positive correlation between ADG and BW during lamb milk feeding resulting in different WW. In our study, no differences were found in lambs’ BW and

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ADG during lactation between R and NR ewes. In addition, Kenyon et al. (2004) pointed out that lamb growth to weaning is influenced by lamb BW and dam milk production.

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In the present study, milk and total milk solids production during lactation were not

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affected by maternal dietary treatments, probably because ewes had enough time to nutritionally recover after restriction when lactogenesis was taking place (Hartmann et al., 1973). Moreover, we did not observe differences in milk conversion efficiency between lambs from both treatments suggesting no compensatory growth at that time. Greenwood et al. (1998) reported that lambs are more efficient converting feed to weight gain if access to feed is not limiting. In the present study, lambs from both treatments attained a feed conversion

ratio of about 5 to 1, so we can infer that milk intake was not limiting for lambs’ performance (Theriez, 1986). At the end, similar BW, ADG and feed conversion ratios resulted in no difference in WW between lambs born to R or NR ewes. In terms of litter size, ewes bearing twin or single lambs did not differ in milk and total solids production in agreement with previous research conducted by Burris and Baugus (1955). However, it is interesting to note that in our experiment, twins were more efficient converting milk to weight gain and this could be explained by a lower weight than singletons with less energy required for

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maintenance (Greenwood et al., 1998). After weaning, growth rate in lambs from R and NR ewes were similar and they

achieved the same final weight to slaughter. Effects of maternal dietary restriction during

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gestation on post-weaning growth rates have been inconsistent. Daniel et al. (2007) and

Piaggio et al. (2018) reported heavier lambs at slaughter from non-restricted ewes compared

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with those of undernourished dams. On the contrary, Ford et al. (2007) observed greater SW

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in lambs from diet-restricted ewes fed at 50% of their nutrient requirements between day 28 and 78 of gestation compared with the control group. Data from the present study showed no significant differences in post-weaning feed intake or feed conversion ratio which is

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consistent with the findings of Daniel et al. (2007) and Piaggio et al. (2018). It has been stated that prenatal effects on muscle fiber development are via the

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regulation of muscle cell proliferation and/or differentiation and therefore, factors that

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increase myoblast proliferation and/or inhibit or delay differentiation are predicted to result in increased formation of muscle fibers (Brameld et al., 2010). Muscle fibers characteristics were not studied in this research but the effects of maternal dietary restriction on carcass parameters and meat quality were minimal. French rack weight and yield (as a percentage of the HCW) was the only valuable cut affected by ewe´s treatments as was found in a previous study conducted by Piaggio et al. (2018). Prior research has shown that nutrient-restricted

ewes during early-mid gestation may have short-term effects on muscle development and after adequate post-natal nutrition, lambs have the capacity to compensate for the changes what results in minor or no negative effect on the carcass characteristics (Daniel et al., 2007; Krausgrill et al., 1999; Norby et al., 1987). In this study, no differences were detected on carcass fatness estimated as the subcutaneous tissue depth at the GR point, probably because dietary restriction was applied to multiparous ewes. Kenyon and Blair (2014) reported that lambs born to primiparous ewes can

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be prone to display a greater level of adiposity than those born to mature ewes. However, it is not determined yet if this increase in adiposity is large enough to affect the value of the carcass or feed conversion efficiency.

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Consumer evaluation of eating quality is the major determinant of meat quality, being tenderness, juiciness and flavor the most important traits (Maltin et al., 2003). Tenderness is

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the most important palatability trait in meat affecting consumer acceptance (Dikeman, 1987;

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Miller et al., 1995). Meat tenderness is mainly affected by the amount and solubility of connective tissue, the composition and contractile state of muscle fibers, and the extent postmortem proteolysis (Joo et al., 2013). In the present study, there was no effect of maternal

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nutrition on lamb meat shear force which agrees with the findings reported by Tygesen et al. (2007) and Piaggio et al. (2018). Color of fresh meat is a particularly relevant trait affecting

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consumers purchase decision (Faustman and Cassens, 1990). Meat color of lambs born to R

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ewes was lighter (greater L* value) than meat of lambs whose dams were NR although it is important to highlight that slight differences in the L* parameter may not be detected by consumers. Furthermore, no significant differences have been reported in lamb meat color as consequence of differential maternal nutrition from day 30 to 80 of gestation (Sen et al., 2016).

Conclusions Data from the present study show that even though ewes were restricted at 60% of their energy requirements for 58 days of gestation (from day 48 to 106) they seem to compensate any detrimental effects on lamb growth if adequate refeeding conditions are provided in late gestation and throughout lactation. Carcass and meat quality of lambs seems to be marginally affected by ewes underfeeding conditions during the above-mentioned

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pregnancy period.

CONFLICT OF INTEREST

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We wish to confirm that there are no known conflicts of interest for the work entitled: “Refeeding ewe’s ad libitum after energy restriction during mid-pregnancy does not affect lamb feed conversion ratio, animal performance and meat quality”, and there has been no significant financial support for this work that could have influenced its outcome.

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Sen, U., Sirin, E., Ensoy, U., Aksoy, Y., Ulutas, Z., Kuran, M., 2016. The effect of maternal nutrition level during mid-gestation on postnatal muscle fibre composition and meat quality lambs. Anim. Prod. Sci. 56, 834-843. http://dx.doi.org/10.1071/AN14663. Taplin, D.E., Everitt, G.C., 1964. The influence of prenatal nutrition on postnatal performance of Merino lambs. Proc. Aust. Soc. Anim. Prod. 5, 72-81. Theriez, M., 1986. The young lamb, in: Church, D.C. (Ed.), Livestock feeds and feeding. 2nd edition. Prentice-Hall, Englewood Cliffs, NJ, pp. 339-353.

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Villette, Y., Theriez, M., 1981. Influence of birth weight on lamb performances. I. Level of feed intake and growth. Ann. Zootech. 30, 151-168.

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Implications for the animal sciences. J. Anim. Sci. 84, 2316-237. https://doi:10.2527/

Table 1 Least square means ± standard error of ewes initial (eIW) and final (eFW) weight during the restriction period, and ewes weaning weight (eWW), according to treatment (Trt), litter size (LS), and its interaction. Trt1

LS2

P-values

R (n = 60)

NR (n = 54)

S (n = 75)

T (n = 39)

Trt

LS

Trt x LS

eIW (kg)

44.8±0.9

44.7±0.9

42.5b±0.8

47.0a±0.9

0.9921

0.0009

0.0354

eFW (kg)

49.3b±0.9

56.8a±0.9

49.9b±1.0

56.3a±1.1

0.0017

0.0002

0.0846

eWW (kg)

48.7±0.9

49.7±0.9

48.2±0.8

50.3±1.0

0.4383

0.1093

0.0881

1

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Trt: treatment; R: TMR to supply 60% of the metabolizable energy requirements for gestation from day 48 to day 106 of gestation; NR: TMR to supply 100% of the metabolizable energy requirements for gestation from day 48 to day 106 of gestation. 2 LS: litter size; S: single-born lamb; T: twin-born lamb. a,b : LS Means assigned with different superscripts in the same row differ significantly (P < 0.05).

Table 2 Least square means ± standard error of birth (BW), weaning (WW), pre-weaning weight gain (preWG), average milk production per ewe per day (MP), average total solids production per ewe per day (TSP), and feed conversion ratio (FCR) of MP of lambs according to treatment (Trt), sex, litter size (LS), and its interactions. Trt1 R (n = 32)

Sex2 NR (n = 32)

M (n = 24)

LS3 F (n = 40)

S (n = 24)

P-values

T (n = 40)

Trt

Sex

LS

Trt x Sex

Trt x LS

Trt x Sex x LS 0.1 598

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BW 4.15±0. 4.30±0. 4.38a± 4.07b± 4.75a±0. 3.70b±0 0.3 0.0 <0.0 0.7 0.8 (kg) 11 10 0.12 0.09 12 .09 247 385 001 472 303 W 23.09± 23.54± 23.76± 22.87± 25.30a± 21.33b± 0.9 0.8 <0.0 0.6 0.0 0.2 W 0.35 0.33 0.39 0.30 0.44 0.33 997 600 001 381 412 546 (kg) pre WG 201.7± 207.0± 211.1± 197.6± 231.7a± 177.0b± 0.4 0.0 <0.0 0.0 0.6 0.4 (g/d 5.72 5.22 6.09 4.78 6.01 4.89 911 865 001 692 855 464 ) MP/ 1.337± 1.413± 1.355±0 1.395±0 0.5 0.74 0.4 d 0.085 0.089 .085 .089 425 36 084 (kg) TSP 0.238± 0.253± 0.243±0 0.248±0 0.4 0.79 0.8 /d 0.014 0.015 .014 .015 743 12 499 (kg) FC R4 4.906± 4.959± 5.860a± 4.005b± 0.9 0.00 0.0 milk 0.306 0.322 0.306 0.322 055 02 777 (kg/ kg) 1 Trt: treatment; R: TMR to supply 60% of the metabolizable energy requirements for gestation from day 48 to day 106 of gestation; NR: TMR to supply 100% of the metabolizable energy requirements for gestation from day 48 to day 106 of gestation; 2 Sex: M: male; F: female. 3 LS: litter size; S: single-born lamb; T: twin-born lamb. 4 Feed conversion ratio expressed as milk intake per kilogram of weight gain. a,b : LS Means assigned with different superscripts in the same row differ significantly (P < 0.05).

Table 3 Least square means ± standard error of initial (IW) and final live weights (FW), postweaning weight gain (postWG), average ration intake per day (RI) and feed conversion ratio (FCR) of the ration according to treatment (Trt), litter size (LS), and its interaction during the fattening phase of the male lambs. Trt1

LS2

P-values

NR (n = 31)

S (n = 28)

T (n = 27)

Trt

LS

Trt x LS

IW (kg)

30.2±0.7

30.2±0.6

33.2a±0.7

27.2b±0.7

0.9710

<0.0001

0.1535

FW (kg)

42.6±0.9

42.6±0.7

45.3a±0.8

40.0b±0.8

0.9924

<0.0001

0.3886

postWG (g/d)

214±7.2

214±6.3

208±6.6

220±7.0

0.9348

0.2334

0.4844

RI (kg/d)

1.463±0.030

1.428±0.026

1.485±0.027

1.407±0.029

0.3789

0.0544

0.8825

FCR3 (kg/kg)

6.99±0.21

6.81±0.19

7.26a±0.20

6.54b±0.21

0.5161

0.0144

0.3166

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R (n = 24)

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Trt: treatment; R: TMR to supply 60% of the metabolizable energy requirements for gestation from day 48 to day 106 of gestation; NR: TMR to supply 100% of the metabolizable energy requirements for gestation from day 48 to day 106 of gestation. 2 LS: litter size; S: single-born lamb; T: twin-born lamb. 3 Feed conversion ratio expressed as ration intake per kilogram of weight gain. a,b : LS Means assigned with different superscripts in the same row differ significantly (P < 0.05).

Table 4 Least square means ± standard error of slaughter weight (SW), total tissue depth over the 12th rib at 11 cm from the midline of the carcass (GR), hot carcass weight (HCW), carcass yield (CYd), carcass length (CL), leg length (LL), frenched rack weight (FRW), leg weight (LW), frenched rack yield (FRYd), leg yield (LYd), Warner-Bratzler shear force (WBSF), and meat color lightness (L*), redness (a*), yellowness (b*), of the male lambs according to treatment (Trt), litter size (LS), and its interaction. Trt1

P-values

NR (n = 31)

S (n = 28)

T (n = 27)

Trt

LS

Trt x LS

SW (kg)

37.5±0.7

37.3±0.6

39.9a±0.7

34.9b±0.7

0.8254

<0.0001

0.2616

HCW3 (kg)

19.3±0.1

19.5±0.1

19.5±0.1

19.3±0.2

0.5453

0.3311

0.1257

CYd4 (%)

51.8±0.4

52.0±0.3

52.2±0.35

51.6±0.4

0.7210

0.3653

0.1125

GR4 (mm)

15.1±0.7

15.0±0.6

14.8±0.7

15.3±0.7

0.9223

0.6933

0.5060

CL4 (cm)

64.5±0.5

64.1±0.4

64.7±0.6

63.8±0.5

0.4741

0.2247

0.8300

LL4 (cm)

36.6±0.2

36.6±0.2

36.6±0.3

36.6±0.3

0.8346

0.9790

0.0548

FRW4 (g)

439b±5.1

459a±4.5

447±5.3

451±5.5

0.0051

0.5624

0.4025

LW4 (g)

1842±15.9

1842±13.8

FRYd45 (%)

2.26b±0.03

2.37a±0.02

LYd45 (%)

9.53±0.08

WBSF 5 d (kg)

3.09±0.22

b* - 5 d

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0.9927

0.4675

0.7209

2.31±0.03

2.33±0.03

0.0052

0.5660

0.3418

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1852±17.0

9.47±0.08

9.59±0.08

0.9822

0.3636

0.7928

3.29±0.19

2.92±0.22

3.47±0.24

0.4947

0.1296

0.0948

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a* - 5 d

1833±16.4

9.53±0.07

40.7b±0.3

41.1±0.3

41.4±0.3

0.0352

0.6056

0.0953

20.2±0.3

19.8±0.3

20.5±0.3

19.5±0.3

0.3336

0.0556

0.3797

5.7±0.2

5.9±0.3

6.4a±0.3

5.3b±0.3

0.5689

0.0176

0.8949

41.8a±0.4

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L* - 5 d

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R (n = 24)

Meat color

1

LS2

Trt: treatment; R: TMR to supply 60% of the metabolizable energy requirements for gestation from day 48 to day 106 of gestation; NR: TMR to supply 100% of the metabolizable energy requirements for gestation from day 48 to day 106 of gestation. 2 LS: litter size; S: single-born lamb; T: twin-born lamb. 3 adjusted by SW. 4 adjusted by HCW. 5 expressed as percentage of HCW. a,b : LS Means assigned with different superscripts in the same row differ significantly (P < 0.05).