Improving triplet lamb survival: management practices used by commercial farmers

Introduction

Prolificacy has become an important breeding goal in sheep farming to increase farm profitability. With the adoption of improved genetics and management practices leading to increased lambing percentages, the proportion of triplet-born lambs has also increased on farms. However, mortality rates of triplet lambs are higher than for single- and twin-born lambs, and additional management inputs may be needed to support survival. The aim of this study was to identify factors that affect management practices that are considered important for triplet lamb survival by commercial farmers from the United Kingdom (UK), the Ireland (IRE), and New Zealand (NZ).

Methods

An online survey was developed and disseminated to farmers in each country, focusing on farmer demographics, flock characteristics, management practices and production outcomes. A total of 448 farmers completed the survey, from the UK (n = 168), IRE (n = 218), and NZ (n = 62).

Results

Respondents had larger flocks, higher scanning and lambing percentages than the country average for the UK and IRE. The mean percentage of triplet litters born within flocks was 9%, and lambs lost between scanning and lambing were 14% for UK, 15% for IRE, and 25% for NZ respondents (P = 0.063). Overall, 60% of all respondents reported to lamb indoors and 40% lambed outdoors, however NZ farmers almost exclusively lambed outdoors, whereas UK and IRE farmers lambed in both systems (P < 0.001). NZ farmers were more likely to rear all triplet lambs with the ewe, whereas UK and IRE farmers were more likely to remove a lamb to rear by another ewe or artificially (P < 0.001). Factors that influenced triplet lamb management practices of respondents in this study were respondent country of origin, flock size, age, and gender. In general, younger respondents (P < 0.001), and female respondents (P < 0.05), were more likely to engage in management activities that were considered to promote better triplet lamb survival, compared to older and male respondents respectively. These practices were associated with better lamb survival reported by respondents but were less likely to be carried out when flock size increased (P < 0.001).

Discussion

The results of this survey highlight future priorities or communication strategies needed to improve triplet lamb survival.

Associations between liveweight, body condition score and previous reproductive outcomes, and the risk of ewes bred at 18-months of age being dry at docking

AIMS Firstly, to investigate associations between liveweight and body condition score (BCS) of two-tooth ewes (18-months-old at breeding) at breeding, pregnancy diagnosis (PD) and pre-lambing and the risk of being dry at docking, on commercial New Zealand sheep farms. Secondly, to investigate the association between previous reproductive outcomes as ewe lambs, and risk of being dry at docking as two-tooth ewes. METHODS Two-tooth ewes (n=9,006) were enrolled in four cohorts from three commercial sheep farms between 2010-14. Ewes were weighed and BCS assessed immediately pre-breeding, at PD (mid-pregnancy) and pre-lambing. At PD, ewes were identified as either non-pregnant, or having single or multiple fetuses. Palpation and examination of udders at docking was used to classify each ewe as either lactating or dry at docking. RESULTS Overall, 437/8,025 (5.4%) of ewes that were diagnosed pregnant at PD were dry at docking. The risk of being dry at docking decreased with increasing pre-lambing conceptus adjusted liveweight (CALW) on all farms (p≤0.002); for 2010-born ewes from Farm A the OR=0.87 (95% CI=0.81-0.92); for Farm B the OR=0.88 (95% CI=0.83-0.92) and for Farm C the OR=0.86 (95% CI=0.79-0.95). The risk of being dry at docking also decreased with increasing CALW gain from PD to pre-lambing for all farms (p≤0.003); for 2010-born ewes from Farm A the OR=0.89 (95% CI=0.84-0.94); for Farm B the OR=0.85 (95% CI=0.81-0.89) and for Farm C the OR=0.88 (95% CI=0.80-0.96). There was no association between BCS at breeding, PD or pre-lambing and the risk of being dry at docking for 2010-born ewes from Farm A, Farm B or Farm C (p>0.05). For 2010-born ewes on Farm A, the risk of being dry at docking was greater for two-tooth ewes that were previously dry at docking as ewe lambs than those that were lactating at docking as ewe lambs (OR=1.7 (95% CI=1.1-2.8); p=0.018), but this difference was not observed for ewes on Farm B or Farm C (p>0.5). CONCLUSIONS There were negative associations between ewe CALW pre-lambing, and CALW gain between PD and pre-lambing, and risk of being dry at docking. For all cohorts, heavier ewes and those that gained CALW were less likely to be dry at docking than lighter ewes or those that lost CALW, however these relationships varied between cohorts.

Early mother–young relationship and feeding behaviour of lambs are unaffected by low pasture allowance until the beginning of the last third of gestation in single-bearing ewes

Nutrition during gestation influences ewes’ bodyweight (BW), the bond with their lamb, milk yield and lamb development, and thus feeding behaviour of lambs during postnatal rearing. The aim of this study was to determine if the level of native pasture allowance from before conception until the beginning of the last third of gestation of single-bearing ewes influences the ewe–lamb relationship at birth and the feeding behaviour of lambs during postnatal rearing. A second aim was to determine whether the nutritional treatments affect ewes’ milk yield and their lambs’ bodyweight. Eleven multiparous Corriedale ewes grazed a high pasture allowance [10–12 kg of dry matter (DM)/100 kg of BW/day; HPA treatment], and another 11 grazed a low pasture allowance (5–8 kg of DM/100 kg of BW/day; LPA treatment) for 145 days beginning 40 days before conception. After the end of this treatment all ewes grazed on Festuca arundinacea and received rice bran and crude glycerine until 3 days before birth. Ewes’ BW was recorded monthly before and during gestation. Latency from parturition until the ewe licked her lamb, latency for lamb to stand up and suckle were recorded, and Maternal Behaviour Score was determined 12–24 h after birth. All the variables recorded during postpartum were determined approximately every 30 days. Grazing, ruminating and suckling events of the lambs were recorded from Day 23 until 142 days of age. Milk yield was determined from 32 until 140 days after lambing. Lambs’ BW was recorded from birth until 140 days of age. On Day 41 the BW change tended to be greater in HPA ewes than in LPA ewes, and on Days 79 and 105 it was greater in HPA ewes than LPA ewes (P = 0.006 and P = 0.005 respectively). Treatments did not affect the behaviours at birth of ewes and lambs, milk yield, ruminating and suckling events of lambs, ewes’ and lambs’ BW. The lambs from HPA ewes tended to present a greater frequency of grazing than the LPA lambs. Different levels of native pasture allowances from before conception until the last third of gestation in single-bearing ewes, followed by an increase in nutrient supply, did not affect ewe–lamb behaviours at birth, milk yield, lambs’ growth, and their feeding behaviours during rearing.

Ad libitum Pasture Feeding in Late Pregnancy Does Not Improve the Performance of Twin-bearing Ewes and Their Lambs

The present study evaluated the effect of controlled ryegrass-white clover herbage availability from day 128 until day 142 of pregnancy in comparison to unrestricted availability, on the performance of twin-bearing ewes of varying body condition score (BCS; 2.0, 2.5, or 3.0) and their lambs. It was hypothesised that under conditions of controlled herbage availability, the performance of lambs born to ewes with a greater BCS would be greater than those born to ewes with a lower BCS. During the period that the nutritional regimens were imposed, the pre- and post-grazing herbage masses of the Control regimen (1,070±69 and 801±30 kg dry matter [DM]/ha) were lower than the ad libitum regimen (1,784±69 and 1,333±33 kg DM/ha; p<0.05). The average herbage masses during lactation were 1,410±31 kg DM/ha. Nutritional regimen had no effect on ewe live weight, BCS and back fat depth or on lamb live weight, indices of colostrum uptake, maximal heat production, total litter weight weaned or survival to weaning (p>0.05). The difference in ewe BCSs and back fats observed among body condition groups was maintained throughout pregnancy (p<0.05). At weaning, ewes from the BCS2.0 group had lower BCS and live weight (2.4±0.2, 74.3±2.6 kg) than both the BCS2.5 (2.6±0.2, 78.6±2.4 kg) and BCS3.0 ewes (2.7±0.2, 79.0±2.6 kg; p<0.05), which did not differ (p>0.05). Ewe BCS group had no effect on lamb live weight at birth or weaning or on maximal heat production (p>0.05). Serum gamma glutamyl transferase concentrations of lambs born to BCS3.0 ewes were higher within 36 hours of birth than lambs born to BCS2.0 ewes and BCS2.5 ewes (51.8±1.9 vs 46.5±1.9 and 45.6±1.9 IU/mL, respectively [p<0.05]). There was, however, no effect of ewe body condition on lamb plasma glucose concentration (p>0.05). Lamb survival was the only lamb parameter that showed an interaction between ewe nutritional regimen and ewe BCS whereby survival of lambs born to BCS2.5 and BCS3.0 ewes differed but only within the Control nutritional regimen ewes (p<0.05). These results indicate farmers can provide twin-bearing ewes with pre- and post-grazing ryegrass-white clover herbage covers of approximately 1,100 and 800 kg DM/ha in late pregnancy, provided that herbage covers are 1400 in lactation, without affecting lamb performance to weaning. The present results also indicate that under these grazing conditions, there is little difference in ewe performance within the BCS range of 2.0 to 3.0 and therefore they do not need to be managed separately.

The allometric relationship between mean fibre diameter of mohair and the fleece-free liveweight of Angora goats over their lifetime

As mean fibre diameter (MFD) is the primary determinant of mohair price we aimed to quantify the lifetime changes in mohair MFD as Angora goats aged and grew. Measurements were made over 12 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins including South African, Texan and interbred admixtures of these and Australian sources. Records of sire, dam, birthweight, birth parity, liveweight, fleece growth and fleece quality were taken for does and castrated males (wethers) (n = 267 animals). Fleece-free liveweights (FFLwt) were determined for each goat at shearing time by subtracting the greasy fleece weight from the liveweight recorded immediately before shearing. A restricted maximum likelihood growth curve model was developed for relating MFD to FFLwt, age and other measurements. A simple way of describing the results is: MFD = κ (FFLwt)β E; where κ is a parameter that can vary in a systematic way with shearing(age), breed, weaning weight, sire, dam and individual; β is a parameter that is the same for nearly the whole study; and E are independent errors from a log-normal distribution. The analysis shows that = 0.34, with s.e. () = 0.021. Thus, mohair MFD was allometrically related to the cube root of FFLwt over the lifetime of Angora goats. However, the allometric proportionality constant differed in a systematic way with age at shearing, genetic strain, weaning weight, sire, dam and individual. For Texan-breed goats, MFD decreased as weaning weight increased (P = 0.00016). The findings indicate that management factors that affect liveweight and weaning weight have lifetime effects on mohair fibre diameter and therefore the value of mohair and the profitability of the mohair enterprise.

Carry-over effects of ewe nutrition and birth rank during the previous pregnancy on the milking performance during the subsequent lactation of Romney ewes

This study investigated whether selection for ewe size and nutrition during the previous pregnancy would affect the lactational performance of the ewe and liveweight gain of her lamb(s) in the subsequent year. A subgroup of singleton-bearing Romney ewes were milked once a week, for 7 consecutive weeks. Singleton-bearing ‘light’ ewes that gave birth to twins in the previous year had reduced milk yields from Day 21 of lactation (L21) onwards in the present year compared with those that gave birth to singletons in the previous year. Lambs born to light ewes had reduced liveweight gain from birth to L21 compared with those born to ‘heavy’ ewes. Singleton-bearing ewes in the present year that were fed maintenance and gave birth to twins in the previous year, produced less milk from L21 onwards compared with those that were maintenance-fed and singleton-bearing in the previous year. Singleton lambs born to milked ewes that were fed maintenance and gave birth to twins in the previous year, had lower liveweight gain from birth to L21 in the present year compared with lambs born to ewes fed maintenance and gave birth to singletons in the previous year. In the entire population, lambs born to ewes fed maintenance and that gave birth to twins in the previous year were lighter at L21 than lambs born to ewes fed ad libitum and bearing twins in the previous year. This indicates that if nutrition is suboptimal, or the ewes are lighter in the previous year, those that were twin-bearing are more likely to rear lighter lambs in the present year. Therefore, farmers need to take these points into consideration when devising feeding plans for the present year.

Effects of twin-bearing ewe nutritional treatments on ewe and lamb performance to weaning

Nutrition of the ewe at various stages of pregnancy is known to affect ewe and offspring performance. However, little is known regarding the potential interactions among differing maternal nutrition regimens in early and mid–late pregnancy. The objective of the present study was to examine the effects and potential interactions of three pastoral nutritional treatments from Day 21 of pregnancy (P21) to P50 (Sub-maintenanceP21–50 (total liveweight change achieved, SMP21-50, –0.15 ± 0.02 kg/day) v. MaintenanceP21–50 (MP21-50,–0.02 ± 0.02 kg/day) v. Ad libitumP21–50 (AdP21-50,0.15 ± 0.02 kg/day) and two pastoral nutritional treatments from P50 to P139 [MaintenanceP50–139 (designed to match change in conceptus mass, total liveweight change achieved, 0.19 ± 0.01 kg/day) v. Ad libitumP50–139 (0.26 ± 0.01 kg/day)] on 382 twin-bearing ewes and their offspring until 91 days after the mid-point of lambing (L91). Ewe liveweight and condition scores in pregnancy and lactation, and lamb liveweights, indices of colostrum uptake and survival were recorded. There were no interactions between nutritional periods for lamb liveweight, apparent colostrum intake and survival, and ewe liveweight, condition score and total weight of lamb per ewe at the end of the study. At L91, ewe nutritional treatment during P21–50 or P50–139 had no effect on either ewe liveweight or body condition score. Ewe nutritional treatment during P21–50 had no effect on lamb birthweight. Lambs born to AdP50–139 ewes were lighter (P < 0.05) than those born to MP50–139 ewes (5.32 ± 0.04 v. 5.48 ± 0.04 kg, respectively). Ewe nutritional treatment during P21–50 or P50–139 had no (P > 0.05) effect on indices of colostrum uptake in lambs at 24–36 h of age. At L91, ewe nutritional treatment during P21–50 or P50–139 had no effect on lamb liveweight, survival or total weight of lamb per ewe. In conclusion, although considerable differences in ewe liveweight were observed during pregnancy, the nutritional treatments had no effect on the production parameters measured at the end of the study. These results indicate, first, that farmers can use early pregnancy as a period to control ewe nutrition when ewes are offered at least pregnancy maintenance levels of nutrition in the mid–late pregnancy period and, second, that there is no advantage from offering twin-bearing ewes a level of nutrition above their pregnancy maintenance requirements in mid–late pregnancy.

Effect of ewe body condition and nutrition in late pregnancy on the performance of triplet-bearing ewes and their progeny

The aim of the present study was to determine the production response of triplet-bearing ewes and their lambs to two differing feeding treatments in mid to late pregnancy and to determine the effect of ewe body condition. Ninety-two days after the start of their breeding period (P92) triplet-bearing ewes, were allocated to either a Medium (n = 72) or ad libitum (‘Adlib’, n = 72) feeding treatment until P113, followed by both groups being merged and offered ad libitum feeding conditions until lambing. The Medium feeding treatment was designed to ensure pre- and postgrazing herbage masses were below 1200 and 1000 kg DM/ha, respectively. Each feeding treatment included ewes from the following body condition score groups: 2.0 or less (CS ≤2.0), 2.5 (CS2.5) or 3.0 or greater (CS ≥3.0). At P113, Medium ewes were lighter (P < 0.05) and had lower (P < 0.05) body condition scores than Adlib ewes (72.4 ± 0.80 vs 75.2 ± 0.85 kg and 2.8 ± 0.06 vs 3.3 ± 0.06, respectively). However, at P141 liveweight no longer differed (P > 0.05, 86.2 ± 0.94 vs 86.6 ± 0.99 kg, respectively), although a small difference in condition score remained (P < 0.05, 3.0 ± 0.07 vs 3.3 ± 0.08, respectively). Ewe feeding treatment had no effect (P > 0.05) on lamb liveweight or survival or ewe liveweight and body condition during lactation. Ewe body condition score group had no effect (P > 0.05) on lamb birthweight. Lambs born to CS2.5 group ewes were heavier 70 days after the midpoint of lambing (L70) than those born to CS ≤2.0 group ewes (20.9 ± 0.41 vs 19.6 ± 0.36 kg, respectively), although they displayed lower survival to L70 (56.0 vs 69.5%). Liveweight at L70 and survival of lambs born to CS ≥3.0 group ewes (20.0 ± 0.39 kg and 61.7%) did not differ (P > 0.05) from those born to either CS ≤2.0 or CS2.5 group ewes. In conclusion, these results suggest triplet-bearing ewes can be maintained under restricted feeding conditions until at least Day 113 of pregnancy without negatively affecting ewe or lamb performance when they are subsequently offered unrestricted feeding for the remainder of pregnancy and during lactation. Under these grazing conditions the body condition of triplet-bearing ewes had little to no effect on their subsequent performance or that of their lambs.

Can a herb and white clover mix improve the performance of multiple-bearing ewes and their lambs to weaning?

The productive performance of highly fecund ewes and their progeny on ryegrass-based swards is limited in late pregnancy and lactation. Alternative herbages, such as chicory, plantain and red and white clover, have the potential to improve performance levels. In the present study, 49 twin- and 42 triplet-bearing Romney composite ewes bred to either Suffolk or Romney rams were allocated to one of three nutritional treatments from Day 131 of pregnancy [19 twin ewes on a ryegrass–white clover sward mix (Rye/WC); 16 twin ewes on a plantain–ryegrass sward mix (Plant/Rye); 14 twin ewes on a chicory–plantain–red and white clover sward mix (Herb); 13 triplet ewes on Rye/WC; 16 triplet ewes on Plant/Rye; and 13 triplet ewes on Herb] and remained on these sward treatments with their lambs until 75 days after the midpoint of the lambing period (L75). Nutritional treatment had no effect (P > 0.05) on ewe liveweight, body condition score (BCS) or non-esterified fatty acid and β-hydroxybutyrate concentrations on Day 145 of pregnancy. At L75, ewes on the Herb treatment sward were heavier than ewes on Plant/Rye (70.75 ± 1.31 v. 61.43 ± 1.28 kg, respectively) and had a higher BCS than ewes on either Plant/Rye or Rye/WC (2.7 ± 0.1, 2.2 ± 0.1 and 2.3 ± 0.1, respectively). Sire type and nutritional treatment had no affect (P > 0.05) on lamb birthweight or weight at L75. At L20, lambs born to ewes on the Herb sward treatment were heavier than those on the Rye/WC and Plant/Rye treatments (8.74 ± 0.23 v. 7.98 ± 0.23 and 7.79 ± 0.22 kg, respectively; P < 0.05). Neither birth rank, sire type nor ewe treatment had any effect (P > 0.05) on maximum heat production on a per kg liveweight basis or total heat production. Romney-sired lambs on the Herb sward treatment had higher (P < 0.05) survival rates than those on the Rye/WC sward treatment (97.8% v. 61.7%, respectively). However, no such relationship was observed in lambs born to Suffolk sires (79.8% v. 84.8%, respectively). The survival response resulted in greater (P < 0.05) total liveweight of Romney-sired lambs at L75 per ewe on the Herb nutritional treatment than on the Rye/WC treatment (61.6 ± 5.0 v. 36.7 ± 4.6 kg, respectively) a relationship not observed (P > 0.05) in Suffolk-sired lambs. In conclusion, the present study indicates that there is the potential to improve the productive performance of multiple-bearing ewes and their lambs by grazing on a Herb sward mix.

Effect of offering concentrate supplement in late pregnancy, under conditions of unrestricted herbage, on the performance of multiple-bearing ewes and their lambs to weaning

The aim of the present study was to determine if offering ewes a commercial concentrate supplement under conditions of unrestricted perennial ryegrass–white clover herbage availability would increase newborn lamb heat production, colostrum intake and subsequent liveweight. Forty seven twin- and 43 triplet-bearing Romney composite ewes (1/2 Romney, 1/4 Finn, 1/4 Texel) were randomly allocated to either non-concentrate or concentrate treatment groups (twin non-concentrate, n = 24; twin concentrate, n = 23; triplet non-concentrate, n = 22; triplet concentrate, n = 21) from Day 79 of pregnancy. Concentrate-fed ewes were offered an increasing amount of concentrate sheep pellets from Day 79 until Day 90 of pregnancy, at which stage ewes were offered 400 g/day per ewe until they lambed. Pre- and post-grazing herbage masses did not differ (P > 0.05) between non-concentrate (2162 ± 54 and 1704 ± 47 kg DM/ha) and concentrate (2135 ± 49 and 1771 ± 42 kg DM/ha) ewes. Ewe nutritional treatment had no effect (P > 0.05) on ewe liveweight, body condition score, β-hydroxybutyate or non-esterified fatty acid concentrations in late pregnancy. Offering concentrates increased (P < 0.05) the birthweight of triplet-born lambs (4.4 ± 0.1 v. 3.9 ± 0.1 kg for those born to concentrate and non-concentrate ewes, respectively) but had the opposite effect on twins (4.8 ± 0.1 v. 5.2 ± 0.1 kg, respectively). There was no difference (P > 0.05) in maximal heat production, total heat production, rate to reach maximal heat production, and IgG concentrations at 24–36 h of age or liveweight and survival of lambs born to ewes offered concentrates or not. Twin-born lambs had greater (P < 0.05) liveweight and total heat production and had higher (P < 0.05) survival rates than triplet-born lambs. In conclusion, the results of the present study indicate that there are only minor beneficial effects from offering concentrate supplements to ewes in late pregnancy under conditions of unrestricted herbage availability and it is not a viable option for farmers to utilise.