Lamb Growth Rate Research Articles

A longitudinal study of factors associated with acute and chronic mastitis and their impact on lamb growth rate in 10 suckler sheep flocks in Great Britain

A 2-year prospective, longitudinal study of 10 suckler sheep flocks in Great Britain was run to identify factors associated with acute mastitis (AM) and chronic mastitis, and their impact on lamb growth rate. Data were collected on AM, intramammary masses (IMM; a marker for chronic mastitis), udder and teat conformation, teat lesions, body condition, ewe nutrition, litter size, lamb weight and general flock management. Each flock was visited twice each year, approximately 4 weeks before lambing and 9 weeks into lactation, for two years and all ewes present at a visit were examined. There were 7021 examinations in total. AM was reported in 2.1–3.0% of ewes/year; this ranged from 0.0% to 37.1% by flock. IMM were detected in 4.7% of ewes in pregnancy and 10.9% of ewes in lactation. Once an IMM had been detected there was an increased risk of future IMM although IMM were not consistently present. The majority of ewes had good udder conformation to suckle lambs. Factors associated with AM, IMM in pregnant and lactating ewes, udder conformation and lamb daily live weight gain were explored using mixed effect multivariable models. An increased risk of AM was associated with underfeeding protein in pregnancy (OR 4.05), forward pointing teats (OR 2.54), downward pointing teats (OR 4.68), rearing≥2 lambs (OR 2.65), non-traumatic teat lesions (OR 2.09); and marginally associated with the presence of IMM. An increased risk of IMM in lactation was associated with AM during lactation (OR 12.39), IMM in pregnancy (OR 4.79), IMM in the previous lactation (OR 4.77), underfeeding energy in pregnancy (OR 6.66) and traumatic teat lesions (OR 2.48). An increased risk of IMM in pregnancy was associated with IMM in the previous pregnancy, IMM in the previous lactation and underfeeding energy in the previous lactation (OR 2.95). Lower lamb daily live weight gain was associated with traumatic teat lesions, IMM in lactation (−0.01kg/day) and AM (−0.04kg/day). We conclude that inadequate nutrition is an important cause of mastitis in suckler ewes which farmers could address in part using current nutritional guidelines but further work is needed. The relationship between AM and IMM indicates that separating or culling ewes with IMM would help reduce AM.

Effect of pre- and post-partum dietary crude protein level on the performance of ewes and their lambs

In a block randomized design, fifty-one Barki ewes weighing 38.0kg in average and 2–4 years old, were used to study the effect of pre- and post-lambing dietary crude protein level (CP) of concentrates on the milk yield, milk composition and weight of ewes, and performance of their lambs. The treatments comprised supplementary concentrate containing (g/kg dry matter (DM)): (1) 110 CP (low), (2) 130 CP (medium) and (3) 150 CP (high), while Egyptian berseem hay (Trifiolium alexandrinum) was the basal diet. Ewes were weighed individually biweekly, and the number of lambs dropped and nursed by ewes was recorded within 24h after birth and biweekly subsequently. New-born lambs were left to suckle their dams freely, except for the period when milk yield was recorded by weighing lambs before and after suckling. Milk yield was estimated once a week. Ewes were fed the experimental diets during the last two months of pregnancy and throughout the lactation period. Ewes fed 110g CP/kg DM attained peak of milk yield earlier than those fed 130 and 150g CP/kg DM. Total milk yield, milk fat and milk total solids, and weaning weight, average daily gain and relative growth rate of lambs were higher (P<0.05) for ewes fed medium and high protein levels compared to those fed low protein level. Suckled milk was affected by protein level (P<0.05); the rank order was: 110CP<130CP<150CP. Milk protein and extractable milk were higher (P<0.05) for high protein level compared to low protein level but solids-not-fat (SNF) and lamb birth weight were not affected (P>0.05) by protein level. Lamb sex, and parity and weight at lambing of ewes had no effect (P>0.05) on suckled milk, extractable milk and milk yield. Whereas lamb sex and parity of ewe had no effect (P>0.05) on milk composition, ewe lambing weight affected (P<0.05) milk fat and SNF but not milk protein and total solids (P>0.05). Weights of ewes during gestation, after lambing (post-partum weight loss) and during lactation were not affected (P>0.05) by protein level, except at the 3rd month of lactation. Lamb sex, parity and lambing weight had pronounced (P<0.05) effects on lamb birth weight and weaning weight. It is concluded that 150g CP/kg DM level pre- and post-partum could be used for improved performance of ewes and their lambs while parity and weight of ewe at lambing should also be given consideration.

Sex influence on genetic expressions of early growth in Afshari lambs

Abstract. Very little is known about the genetic aspects of sexual dimorphism of body weight in domestic sheep, and therefore this study was conducted to quantify the genetic basis of sexual dimorphism for early-growth-related traits in Afshari lambs. Traits evaluated included birth weight (BW), weaning weight (WW), and growth rate (GR) in male and female lambs. Male lambs were 6.6 % heavier at birth, had 14.4 % higher preweaning growth rates and were 16.0 % heavier at weaning compared to female lambs. Levels of sexual-size dimorphism (SSD), expressed as the ratio of male to female means, for BW, WW and GR were 1.07, 1.14 and 1.15, respectively, which indicated low levels of SSD in the traits studied. Fixed effects of year of birth and type of birth interacted with sex effects, with greater variability in birth and weaning weights among years and birth types in male lambs, suggesting greater environmental sensitivity in the males. Bivariate animal models and restricted maximum likelihood (REML) procedures were used to estimate phenotypic variances and their genetic and non-genetic components in male and female lambs. Estimates of the direct heritability (h2) and additive coefficient of variation (CVA) for BW were higher in males. However, for WW and GR, heritability estimates were higher in females. In contrast, whereas the contribution of maternal permanent environmental effects (c2) to variation of BW was higher in females, for WW and GR higher estimates of c2 were observed in males. Respective genetic and maternal permanent environmental correlations between records on males and females were 0.986 and 0.723 for BW, 0.995 and 0.983 for WW, and 0.995 and 0.966 for GR, indicating possible sexual dimorphism only for maternal effects on BW. Based on an approximate 95 % confidence interval, none of the observed differences in variance components between sexes differed from zero and none of the observed genetic or maternal correlations differed from 1.0, indicating no need or opportunity for sex-specific selection strategies.

Growth and Haemato-Biochemical Response in Lambs in Relation to Supplementary Feeding of Ewes in Late Pregnancy

A study was undertaken to elucidate the effect of concentrate supplementation (eight weeks before the expected date of lambing) to native ewes in coastal Odisha on lamb growth and haemato-biochemical profile. Forty pregnant ewes (12 months old) were randomly distributed into two groups (T-1 and T-2). Ewes of T-1 were maintained on grazing only while ewes of T-2 were supplemented with concentrate mixture @ 200 g/sheep/day along with grazing. Significantly (P<0.01) higher birth weight and growth was observed in T-2 group lambs. The lambs in T-2 showed significantly (P<0.05) higher haemoglobin, packed cell volume, blood glucose, total protein and globulin values in the pre-weaning period than those in T-1. It was concluded that pre-partum concentrate feeding @ 200 g/day/ewe to the pregnant ewe improved birth weight and growth rate of lambs.

Effects of shed modifications on ewe reproductive performance and lamb growth rate in Inner Mongolia

The effects of warm sheds on the performance of ewes and their lambs in winter are poorly understood. The aim of the present study was to examine the effects of traditional sheds (TS + grazing) and modified warm sheds (WS, no grazing) on the reproductive performance of ewes (as well as their liveweight) and their lambs during the winter–spring period. Cross-bred ewes (n = 120) were randomly assigned to two treatments, either TS (+ grazing) or WS (no grazing), during the winter–spring period of 2011, 2012 and 2013. This study was conducted on two adjacent farms with the two treatments applied on each. The ewes in the TS treatment were grazed continuously on pasture in the day and housed in traditional sheds each evening, whereas the ewes in the WS treatment were not grazed. The animals in each treatment were fed the same amount of feed. Ewes housed in the WS group had a higher liveweight and lower weight loss than ewes in the TS group (P = 0.004 and 0.005 respectively); over the 3 years, the weight loss of the ewes in both groups was worst in the first 2 months (December–January) compared with the later 2 months, and was significantly alleviated after the first year (2011; P &lt; 0.001). Lamb liveweight and gain were higher in the WS than TS treatment group (P &lt; 0.001) and the growth rates of the lambs increased continuously as shed temperatures increased. Lamb weight gain and birthweight increased significantly with increasing years of the experiment (P &lt; 0.001). There were more lambs born in the WS than in the TS groups (P = 0.020), with higher survival and twinning rates (P &lt; 0.05). As shed temperatures increased, lambing, survival and twinning rates increased continuously. Therefore, keeping livestock in warm sheds during the winter and spring period will lift animal productivity, leading to improved household incomes. Elimination of winter grazing will reduce damage to already degraded grasslands and will assist herders to develop more positive attitudes towards animal production enterprises.

Influence of Maternal and Postweaning Linseed Dietary Supplementation on Growth Rate, Lipid Profile, and Meat Quality Traits of Light Sarda Lambs.

The effects of dietary extruded linseed (EL) on growth performance, meat quality, and lipid profile of Semimembranosus and Longissimus lumborum muscles of 81 Sarda lambs were studied in a 3 × 3 design: EL content (0%, 10%, and 20%) of maternal dietary concentrate fed from 20 d to parturition to 60 d of lactation and EL content (0%, 10%, 20%) of lamb concentrate fed after weaning for 30 d. The basal diet was composed of alfalfa and meadow hay during pregnancy and alfalfa hay during lactation. At slaughter, carcass and meat quality were evaluated. Sensory quality of Semimembranosus from 0% and 20% EL lambs was assessed. Both maternal and postweaning diets affected growth performance, with higher body weights recorded with the 10% EL concentrate. Carcass and meat quality were not affected by diet. Saturated and monounsaturated FA decreased and n-3 polyunsaturated FA increased with increasing EL content in lamb diet. An increase in vaccenic and rumenic acid was associated with the EL content of the maternal diet. Both diets increased the n-6/n-3 FA ratio. No differences in acceptability were detected by consumers among groups. It is concluded that EL supplementation and early life nutrition can influence performance and FA metabolism in growing lambs.

Supplementation of Fenugreek Seeds to Lactating Ewes and Effect on Growth Performance of Preweaned Twin Lambs

A study was conducted in lambs to find out the efficiency of fenugreek seed (FS) supplementation in twin bearing ewes. The dams were grouped as follows with seven dams in each group. The groups were dam's that lambed twins supplemented with FS (T1), Dams that gave birth to single lambs supplemented with FS (T2) and dams gave birth to single lambs without FS (T3). The FS supplemented dam groups were given 10 g of fenugreek seed per day. The study suggest supplementation of FS @ 10 g each day to lactating ewes carrying twins support lamb weight gain better than single birth lamb and reduced the degree of mother weight loss. The significance difference at 0.05%. Among single birth lambs, FS supplemented group was better both in terms of growth rate of lambs and reduction in the ewes weight.

Liveweight production of ewes and lambs grazing a dryland lucerne monoculture with or without barley grain supplementation

In 2013/2014 (Year 1) and 2014/2015 (Year 2) at Ashley Dene, Canterbury, New Zealand, sheep grazing dryland lucerne monocultures were supplemented with barley grain. In neither year did barley grain supplementation improve lamb growth rates. In 2013/2014 total liveweight (LWt) production of lambs was 782 ± 11.5 kg LWt/ha between 3/9/2014 and 3/2/2015 when pastures were destocked. However, ewes with continuous access to barley grain gained 12.4 kg LWt/ha over the lactation period compared with those without access to grain that lost 14.0 kg LWt/ha. In 2014/2015 (Year 2), liveweight production of lambs totalled 408 ± 1.0 kg LWt/ha from those with no access to grain and 382 ± 1.0 kg LWt/ ha from those with grain supplementation. Upon restocking with weaned lambs, each lamb with access to grain gained 154 ± 9.8 g/d which was less than those without grain access (188 ± 9.7 g/d). Sheep ingested 25-83 g/d of grain with ad lib feeding. These results support previous literature that suggests liveweight responses from grain supplementation of sheep are inconsistent. Keywords: alfalfa, Medicago sativa, Hordeum vulgare, feed conversion efficiency

Essai d’une complémentation alimentaire au flushing et au steaming de brebis Ouled Djellal par la caroube

La présente étude a pour but la substitution d’un concentré à base de caroube entière à un concentré à base d’orge. Elle a concerné cinquante brebis, réparties aléatoirement en deux lots: un lot témoin ayant reçu une complémentation à base d’une ration R1 constituée de 30 % son de blé et de 70 % d’orge en grains au flushing puis au steaming, et un lot expérimental qui a reçu un concentré R2 à base de 30 % de son de blé et de 70 % de caroube entière. L’impact de cette complémentation a été évalué par les notes d’état corporel (NEC) à la lutte et à la mise bas, les performances de reproduction ainsi que la croissance des agneaux. Les NEC ont été significativement identiques entre les deux lots à la lutte (3,33 vs. 3,48) et à la mise bas (2,87 vs. 2,94). De même, les vitesses de croissance ont été significativement similaires (p&gt;0,05). Ainsi, les compléments énergétiques (orge vs. caroube) peuvent se substituer.

Effects of ewe live weight and age on reproductive performance, lamb growth, and survival in Central Anatolian Merino sheep

&lt;p&gt;&lt;strong&gt;Abstract.&lt;/strong&gt; The aim of this study was to evaluate the effects of premating ewe weight and age on ewe reproductive performance, lamb growth and survival in Central Anatolian Merino (CAM) sheep. &lt;br&gt;&lt;br&gt; The trial included 4935 ewes and 5548 lambs from 23 breeder flocks in Eskişehir Province. The live weights (LWs) and ages of the ewes were recorded 1 week before the mating season. The number of lambs born, fertility rate, multiple birth rate (MBR), and lamb survival rate (SR) at days 75 and 120 were determined. The effects of the LW and age of the ewe were found to be important for the reproductive performance of ewes and for the lamb's growth rate (&lt;i&gt;P&lt;/i&gt; &lt; 0.05–0.001). Ewe MBRs and the birth weight (BW) and LW of the lambs at days 75 and 120 increased proportionally with the increase in LW in ewes prior to mating. The fertility rate and MBR were lower (&lt;i&gt;P&lt;/i&gt; &lt; 0.05–0.001) in 1.5-year-old ewes than in older ewes. However, lambs' SR at days 75 and 120 were not affected by the premating LW and age of the ewe. In summary, a better reproductive performance and lamb growth rate in CAM flocks may be achieved by the selection of breeding ewes from ewes weighing more than 60 kg.&lt;/p&gt;

Effects of weaning age on growth, nutrient digestibility and metabolism, and serum parameters in Hu lambs.

This study was conducted to investigate the effect of weaning age on growth performance, nutrient digestion and metabolism, and serological indicators, and to obtain an optimal weaning age in Hu lambs. Forty-eight newborn Hu lambs (birth weight, 2.53 ± 0.14 kg) were randomly divided into 4 groups. The lambs in control group (ER) suckled their dams. The lambs in other three experimental groups were weaned on milk replacer at 10, 20, and 30 days of age (EW10, EW20, and EW30 groups), respectively. The results were as follows: 1) lambs in EW10 and EW30 groups had a lower (P < 0.05) ADG than those in ER group within 10 days post-weaning; the weaned lambs began to show a higher (P < 0.05) ADG than those in ER group after 20 days post-weaning. 2) EW10 and EW20 groups had a higher (P < 0.05) creep feed intake than EW30 and ER groups from 15 to 60 days of age. 3) The apparent digestibility of dry matter, organic matter, gross energy, nitrogen, ether extract and phosphorus, and the deposition of nitrogen and phosphorus did not differ (P > 0.05) among groups; however, the apparent digestibility and deposition of calcium in early weaned lambs were lower (P < 0.05) than those in ewe-reared lambs. 4) The albumin content in EW30 group was lower (P < 0.05) than that in ER group; the globulin content in EW30 group was higher (P < 0.05) than that in other groups; the content of serum insulin-like growth factor-Ⅰ in weaned lambs tended to increase compared with lambs in ER group. Finally, the growth rate of lambs decreased within 10 days post-weaning, but early weaning boosted creep feed intake, leading to better growth and health later in life. The Hu lambs can be weaned on milk replacer and creep feed at 10 days of age.

Lamb growth rates and optimising production

Low profitability and poor economic returns are common complaints from a number of commercial sheep farmers, yet many do not measure their production costs or monitor lamb performance. Disappointing growth...

Effect of variation in ovine WFIKKN2 on growth traits appears to be gender-dependent.

WFIKKN2 may play a role in the regulation of muscle growth and development, but to date there have been no reports on the effect of variation in WFIKKN2 on growth and carcass traits in livestock. In this study, the effect of variation in ovine WFIKKN2 was investigated in 800 New Zealand Romney lambs (395 male and 405 female), with five previously described variants (A to E) being identified. Variation in ovine WFIKKN2 was not found to affect various growth traits in the female lambs, but the presence of variant B was associated (P < 0.05) with decreased birth weight, tailing weight, weaning weight and pre-weaning growth rate; and increased post-weaning growth rate in male lambs. In male lambs, the presence of variant B was associated (P < 0.05) with an increased shoulder yield and proportion shoulder yield. No associations with growth or carcass traits were detected for the presence (or absence) of the other variants. These results suggest that variation in ovine WFIKKN2 may have a differential effect on growth in male and female lambs, and hence that the gene may be expressed in, or act in, a gender-specific fashion.

Productive response of lambs fed Crescentia alata and Guazuma ulmifolia fruits in a tropical region of Mexico.

In vitro gas production with and without polyethylene glycol (PEG) of the fruits of Crescentia alata and Guazuma ulmifolia was evaluated, the degradation kinetics of lamb diets with added fruit of the tree was determined, and the ration intake and growth rate of lambs fed these diets were measured. Twenty-five entire male lambs of 23.5 ± 0.44 kg body weight were used and distributed in treatments: T0 (control without fruit); T1 and T2, 15 and 30 % of the fruit of C. alata; and T3 and T4, 15 and 30 % of the fruit of G. ulmifolia. Data variables chemical composition, fermentation kinetic, and digestibility in vitro were analyzed by a completely randomized design and data production response factorials design of five treatments by three evaluation periods. The total phenolic content (TP) (23.0 g/kg DM) was higher (P < 0.01) in the fruits of G. ulmifolia. The addition of PEG increased (P < 0.05) in vitro gas production (156.6 mL/g DM) in fruits of G. ulmifolia. In the fermentation kinetics, the total gas volume was higher (P < 0.01) at T0 (b = 293 mL/g DM), and the rate of degradation (c) but Lag time (t lag) was not different. In animal response, total dry matter intake was higher in lambs that received T4 (1.35 kg), and the daily weight gain and feed conversion did not differ (P > 0.05) among lambs receiving the treatments. Thirty percent G. ulmifolia fruit added in the diet increased dry matter intake and improved feed conversion but did not increase weight gain.

Effects of behavioral reactivity on production and reproduction traits in Dorper sheep breed

Abstract The aim of the current research was to evaluate the effects of behavioral reactivity on production and reproduction performance in Dorper sheep, a meat breed. Temperament of animals was subjectively evaluated using a 5-point scoring system at weighing, during which sheep spent 30 seconds on the scale. The heritability of temperament was low (0.10 ± 0.03). Estimated phenotypic ( r p ) and genetic ( r g ) correlations between temperament and litter size in ewes were negative and negligible ( P > 0.05) at −0.06 ± 0.18 and −0.08 ± 0.09, respectively. Significant genetic correlations were found between lamb temperament and preweaning growth rate ( r g = −0.44 ± 0.07, P ≤ 0.05) and postweaning growth till the age of 120 days ( r g = −0.52 ± 0.08, P ≤ 0.05). Significant genetic correlations were found between lamb temperament and growth rates during their first 3 months of age. As a result, selection for calm temperaments should translate to increased growth rates of lambs. Negative correlations between temperament and production traits, both in ewes and lambs, suggested that selection against animals that are highly reactive to improve welfare and ease of handling would not have detrimental impacts on productivity.

Impact of &amp;lt;i&amp;gt;Saccharomyces cerevisiae&amp;lt;/i&amp;gt; supplementation on reproductive performance, milk yield in ewes and offspring growth

Abstract. The effect of supplementing sheep diets with Saccharomyces cerevisiae Inter Yeast® dried brewer's yeast (Leiber GmbH, Bramsche, Germany) or with a Biolex® Beta-S (Leiber GmbH, Bramsche, Germany) extract containing over 70 % β-1,3/1,6-D-glucan was investigated. Experiment 1 was carried out with 120 ewes and 190 lambs. The animals were divided into three groups: I – control; II – fed yeast; and III – fed Biolex. The supplements were administered during a 3-week preparation period for tupping and a 70-day lamb-rearing period. The following reproductive parameters were analysed: fertility, prolificacy, lamb rearing and breeding performance, milk yield and lamb growth rate. Experiment 2 was conducted with 120 ewes divided into two groups: I – control and II – fed yeast during a 3-week preparation period. Fertility and prolificacy were analysed. Significant increases in prolificacy were recorded in sheep administered dried brewer's yeast: 28.51 % in experiment 1 and 31.33 % in experiment 2. Breeding performance was also higher by 35 %. Both yeast supplements had a stimulating impact on the milk yield of ewes and the growth rate of their offspring. Milk from the experimental ewes, especially in the group fed Biolex, had a substantially higher content of dry matter, mainly fat. The lambs in this group had the highest body weight at the age of 70 days. Finally, however, the production of livestock per mother was highest in the group fed the supplement with Saccharomyces cerevisiae.

Removal of tapeworm (Moniezia spp.) did not increase growth rates of meat-breed lambs in the Northern Tablelands of NSW

This experiment tested the hypothesis that growth rates of meat-breed lambs would not be affected by infection with tapeworm (Monieza spp.). Two experiments, conducted in successive years (2012 and 2013) on a commercial sheep farm on the Northern Tablelands of NSW, assessed growth rates of meat-breed lambs, between 4 and 6 months of age, following the removal of the cestode, Monieza spp. (or commonly referred to as tapeworm). In 2012 and 2013, 93 and 85 lambs respectively were randomly allocated to two treatment groups. One group (Prazi) was treated with praziquantel, levamisole and abamectin to remove tapeworm and gastrointestinal nematode infection (GIN) while the second group (Control) was treated with levamisole and abamectin to remove only GIN. Tapeworm prevalence and egg counts of Control lambs ranged from 25 to 77% and 7 to 730 eggs per gram (epg) respectively and were significantly (p<0.005) reduced in Prazi lambs, following treatment, at all time-points in both years. Pre-treatment GIN worm egg counts ranged between 1684 and 3368epg with Haemonchus contortus the dominant species. Post-treatment GIN worm egg counts were similar between Prazi and Control groups, expect on one occasion (Day 65, 2013) when GIN worm egg counts were expectantly higher (p<0.005) in Control lambs. No significant difference in growth rates were observed between treatment groups in either year with overall group mean daily bodyweight gains being 95 and 81g/day (p=0.053) in 2012 and 132 and 134g/day (p=0.784) in 2013 for the Prazi and Control groups respectively. This experiment confirmed that removal of tapeworm burdens did not increase growth rates in meat-breed lambs on a commercial sheep farm in the Northern Tablelands of NSW.

Productive and Reproductive Performance of Ewes and Growth Rate of Lambs as Affected by Non - Conventional Energy Supplement to Rations

Productive and Reproductive Performance of Ewes and Growth Rate of Lambs as Affected by Non - Conventional Energy Supplement to Rations

Influence of nutrition supplementation on the seasonal change in fiber growth and skin follicle activity in both male and female Sanjabi lambs

The present work aimed to investigate the effect of nutrition supplementation on skin follicle activity and wool growth rate in male and female Sanjabi lambs during the autumn and winter seasons, when the natural daylength is declining and being shortest. Twenty male (control and male (CM), n=10; treatment and male (TM), n=10) and 20 female (control and female (CF), n=10; treatment and female (TF), n=10) Sanjabi lambs were housed in individual pens, under natural daylength condition at west of Iran, Kermanshah (34°18′ N and 47°3′ E and 1420m above sea level). Lambs in control groups received a diet consisting of 80% alfalfa and 20% concentrate, providing 2.18Mcal and 130.0g per kg DM ME energy and crude protein, respectively. In treatment groups, lambs were fed a diet consisting of 65% alfalfa and 35% concentrate, providing 2.34Mcal and 160.0g per kg DM ME energy and crude protein, respectively. Raw and clean fiber growth rates and fiber diameter were measured from left mid-side patches harvested at the end of every month. Percentage of active primary and secondary follicles (PAP and PAS), follicular density (FD) and the ratio of secondary to primary follicles (S/P) were measured from skin biopsies, taken from the right mid-side of the lambs in monthly intervals. PAP and PAS in autumn were significantly (p<0.01) higher than those observed in winter season. There was a positive effect of feeding supplementation on both PAP and PAS but, similar values for S/P ratio and FD were observed in control and treatment groups. All hair follicle parameters viz. PAP, PAS, S/P ratios and FD were significantly greater in females compared to male lambs. The rate of wool growth was significantly lower in winter compared to autumn season, although similar fiber diameter was recorded in two seasons. Male lambs compared to females had greater body weight, DMI and the rate of wool growth. It is concluded that the fiber follicle activity and therefore wool growth in Sanjabi lambs is mainly under influence of nutrition, nonetheless little monthly fluctuation in follicle activity and fiber growth and diameter was observed. Likewise, there was a different pattern of wool production in male and female Sanjabi lambs.

Stocking rate effects on liveweight gain of ewes and their twin lambs when grazing subterranean clover-perennial grass pastures

Two grazing experiments were conducted on non-irrigated tall fescue–subterranean clover and cocksfoot–subterranean pastures subject to summer-dry conditions in Canterbury, New Zealand, to measure the effect of low (8·3–10 ewes and their twin lambs ha−1) vs. high (13·9–20 ewes and their twin lambs ha−1) stocking rates (SR) on lamb and ewe liveweight gain in spring. In tall fescue–subterranean clover pasture, lambs grew faster at low (374 g per head d−1) than high (307 g per head d−1) SR, but total liveweight gain per ha was greater at high (12·3 kg ha−1 d−1) than low (7·5 kg ha−1 d−1) SR. In successive years in spring in cocksfoot–subterranean clover pastures, lambs grew faster at low (327, 385 g per head d−1) than high (253, 285 g per head d−1) SR but total liveweight gain per ha was greater at high (7·26, 7·91 kg ha−1) than low (5·43, 6·38 kg ha−1) SR. These studies indicate that in summer-dry areas, subterranean clover-based pastures will support high twin lamb growth rates in spring, with lower SR leading to higher lamb growth rates and more lambs reaching slaughter weights before the onset of dry conditions.