Is plantain ( Plantago lanceolate L.), chicory ( Cichorium intybus L.) and clover mixtures effective on weaned lamb growth?

The research was undertaken to assess the lamb production performance over two consecutive years (2011/2012 and 2012/2013) on three sward mixtures; Pasture mixture, Plantain mixture and Chicory mixture in early spring, late spring, summer and autumn. The Pasture mixture consisted of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) whereas the Plantain mixture was included with plantain (Plantago lanceolata L.), white clover and red clover (Trifolium pratense L.). The Chicory mixture contained plantain, chicory (Cichorium intybus L.), whiteand red-clover. It was hypothesised that the highest lamb live weight gain (LWG) and carcass weights would be obtained by feeding Plantain and Chicory mixtures in all four periods. In each period weaned lambs were reared on the three herbage treatments for a maximum of two months. The lambs were weighed fortnightly throughout the experimental period and slaughtered at the end. Both Plantain and Chicory mixtures produced higher (P<0.05) LWG and carcass weights compared to the Pasture mixture in all periods. Both Plantain and Chicory mixtures had lower (P<0.05) feed conversion ratios (FCR) and higher (P<0.05) herbage utilization efficiencies compared to the Pasture mixture. This research has shown that sheep farmers in New Zealand can finish lambs at a faster rate for heavier carcasses from spring to autumn using herb-clover mixtures than using ryegrass/white clover pastures.


INTRODUCTION
A mixture of ryegrass (Lolium perenne L.)/white clover (Trifolium repens L.) is the main feed available for grazing livestock in New Zealand (Hodgson et al., 2005). However, the quality and production of this herbage mixture is seasonal. Ryegrass/white clover production is limited due to the low soil moisture levels during summer (McKenzie et al., 1999) and the quality can be low due to high fibre content (Hodgson and Brookes, 1999). Hence, farmers adjust the stocking rates to accommodate the poor herbage production and quality by slaughtering the lambs in summer and autumn, more than in other periods of the year (Webby and Bywater, 2007;Beef+Lamb New Zealand, 2014). These factors contribute to low lamb growth rates and hence, low carcass weights during summer and autumn (Fraser et al., 1999;Powell et al., 2007).
Thus, finding alternative pastures or herbage species that are of high quality and produce significant quantity from early spring to late autumn, would be of benefit to the New Zealand lamb meat production system. Earlier research showed that herbages such as plantain (Plantago lanceolata L.), chicory (Cichorium intybus L.), white clover and red clover (Trifolium pratense L.) have a higher nutritive and feeding value than the ryegrass (Barry, 1998;Hodgson and Brookes, 1999;Waghorn et al., 2007;Hayes et al., 2010). Thus this paper discusses lamb production performance on three herbage treatments (Pasture mixture vs Plantain mixture vs Chicory mixture) over two consecutive years. It was hypothesised that the Plantain and Chicory mixtures (herb-clover mixtures) would produce higher lamb live weight gains and carcass weights on a per animal basis compared to the Pasture mixture.

Experimental site and treatments
A research was undertaken at the Moginie Pasture and Crop Research Unit, Massey University, Palmerston North, New Zealand (40 0 21' S, 175 0 37' E, and altitude of 30 m). Ten experiments were undertaken in two consecutive years (Year one: 2011/2012and Year two: 2012/2013) in five different periods; winter, early spring, late spring, summer and autumn in each year. The experimental design was nested linear model. The experiments consisted of three herbage treatments; (i) 'Pasture mixture' with perennial ryegrass (One50 cultivar) and white clover (Bounty cultivar); (ii) 'Plantain mixture' with plantain (Ceres Tonic cultivar), white clover and red clover (Sensation cultivar); and (iii) 'Chicory mixture' with plantain, chicory (Puna II cultivar), white-and red-clover. These experiments received the Massey University Animal Ethics Committee approval.
There were three mobs of lambs per each herbage treatment serving as replicates. Total grazing area per herbage treatment was 2.25 ha consisting of three replicates (0.75 ha × 3). Each replicate had three 0.25 ha paddocks for rotational grazing.

Animal management
Lambs were given a five days adaptation period before commencing each experiment. Crossbred weaned lambs (cryptorchids) were stratified by live weight and allocated in herbage treatments at the start of each experiment. Every 28 days lambs were drenched with Ancare 'Matrix' triple combination drench (1 ml per 5 kg body weight); active ingredients 1 g/l Abamectin; 40 g/l Levamisole HCL; 22.7 g/l Oxfendazole (Merial Ancare, Manukau City, New Zealand). The stocking rates used in each experimental period were given in Table  1. Adult ewes were introduced to the experiments after first year late spring at a rate of six ewes per herbage treatment to maintain a refugia population of gastrointestinal nematodes at the farmlets (Waller, 1999) as the ewes were not routinely drenched with anthelmintic drugs. Different ewes were used for different experiments. Lambs were reared only in the Pasture mixture during the winter period. The Plantain and Chicory mixtures were not grazed during the winter period as plantain, chicory and red clover were partially dormant during the winter (Valentine and Kemp, 2007;Kemp et al., 2010). The Pasture mixture was grazed hard using ewes whenever necessary to maintain the pasture quality in late spring and summer. At the end of the first rotation during summer Plantain mixture and the Chicory mixture paddocks were mowed to a height of 10 -12 cm to remove the seed heads and other reproductive structures (Labreveux et al., 2006) and two to three weeks' rest period was maintained to allow the pasture and herbage to re-grow to the prescribed herbage mass and heights before commencement of the next experiment. Ad-lib feeding was practised during experiments allowing three times predicted intake (Kenyon and Webby, 2007). Lambs were rotated when the post-grazing sward surface height reached 5 cm in the Pasture mixture or 7 cm in the Plantain and Chicory mixtures. Lambs were weighed (un-fasted) fortnightly. Each experiment was conducted until either the lambs gained 10 kg body weight or for maximum 56 days or the herbage/pasture growth was not sufficient to meet lamb ad-lib feeding requirements. The initial live weights of the lambs were given in Table 2. At the end of each experiment lambs were trucked in the late afternoon and slaughtered at Alliance Meat Works (Dannevirke, New Zealand) in the early morning of the following day.

Herbage quality measurement
Two samples of herbage were plucked at each post-grazing from the enclosed cages placed in each paddock and frozen at -20 0 C for herbage quality analysis. Herbage was analysed for crude protein (AOAC 968.06 and Leco Total Combustion Method [LECO Corporation, St. Joseph, MI, USA]), neutral detergent fibre (NDF) and acid detergent fibre (ADF) according to Robertson and Van Soest, (1981), In vitro organic matter digestibility (OMD) and digestible organic matter digestibility (DOMD) according to Roughan and Holland (1977). Metabolizable energy (ME) was calculated by multiplying DOMD% by 0.163 (Geenty and Rattray, 1987).

Other calculations
Feed Conversion Ratio (FCR) and efficiency of herbage utilization (EHU) were calculated on dry matter (DM) basis using the equations (Eq I and Eq II). The assumptions given in Nicol and Brookes (2007) were used in the calculation of FCR and EHU. FCR = Total feed required for maintenance + growth (kg DM per ha)-----------------Eq I Total live weight gain per ha (kg per ha) The assumptions; The requirement of metabolisable energy (ME) for maintenance; eg. 40 kg lamb = 8.0 MJ ME/day and 50 kg lamb = 9.5 MJ ME/day The requirement of ME for growth; eg. 35 kg lamb = 3.0 MJ ME/100 g LWG and 45 kg lamb = 3.5 MJ ME/100 g LWG The total dry matter (DM) requirement for maintenance and growth; = ME requirement for maintenance/lamb + ME requirement for growth/lamb × SR ME content of the herbage treatment SR = stocking rate and, Total live weight gain/ha/mob (replicate); = (mean end live weight -mean initial live weight) × SR EHU = Total feed required for maintenance + growth (kg DM per ha) × 100 --------Eq II Apparent herbage utilization (AHU) (kg DM per ha) where, AHU for lambs for each experiment was calculated by; AHU = Apparent herbage disappearance (kg DM per ha) × total herbage growth (kg DM per ha) where, apparent herbage disappearance was calculated by; = pre-grazing herbage DM mass -Post-grazing herbage DM mass and total herbage growth was calculated by; Total herbage growth = herbage growth per day × duration of the grazing period

Statistical analysis
Data were analysed using General Linear Model (GLM) procedure in SAS version 9.2 (SAS, 2008). The model included herbage treatment, period and their interaction as fixed effects and the mob of lambs (replicate) effect nested within the herbage treatment x period interaction as a random effect. Winter data were analysed separately using ANOVA with mob as a fixed effect using GLM procedure for each experiment. Feed conversion ratio (FCR) and EHU data were analysed using a randomized block design model with herbage treatment as a fixed effect and mob as a random effect using GLM. The means were separated using least significant difference procedure (LSD).

Annual nutrient quality of herbage treatments
There were significant differences (P < 0.05) in all herbage quality measurements of the sward mixtures except for CP (Table 3) The present study shows that plantain and chicory based herb-clover mixtures had higher nutritive value in terms of OMD and ME compared to the Pasture mixture supporting the findings of Cave et al. (2015) and Pain et al. (2014). This difference was also reported by Golding et al. (2011) in late summer/early autumn period. 18.2 ± 1.37 22.5 ± 1.37 21.5 ± 1.37 Ash (%) 9.4 a ± 0.53 11.4 b ± 0.53 12.9 b ± 0.53 Differing superscripts (a,b,c) within rows and years indicate means that were significantly different (P < 0.05). 1 Excluding winter data.

Live weight gain (LWG) and dressing out percentage (DO%) of lambs between different periods
The effect of feeding herb-clover mixtures on the weaned lamb growth are shown in Table 4. During late spring, summer and autumn lambs fed with Plantain and Chicory mixtures had higher LWG than the lambs fed with the Pasture mixture. During year one early spring lambs in the Plantain mixture had similar LWG as the lambs in the Pasture and Chicory mixtures. However, in year two early spring Plantain mixture lambs had the highest (P < 0.05) LWG than the lambs in the other two sward mixtures. Golding et al. (2011) reported a greater LWG in a herb-clover mixture similar to the Chicory mixture during late summer/early autumn period. The faster lamb growth rates may have attributed by the higher quality in the herb-clover mixtures throughout early spring to autumn period. With higher nutrient digestibility and energy content combined with the higher rate of feed passage (Hodgson and Brookes, 1999;Litherland et al., 2010) may have resulted such faster growth rates in lambs on herb-clover mixtures. The higher fibre percentage could limit feed intake and negatively affect lamb growth in the Pasture mixture (Burke et al., 2002;Waghorn et al., 2007). Dressing out percentage (DO%) is expressed as a carcass in proportion of final live weight (Kirton et al., 1984). Greater carcass weights (Table 5) obtained from both Plantain and Chicory mixtures compared to those of the Pasture mixture in the present study resulted higher DO% (DO% data were not shown in the present paper). Similarly, Golding et al. (2011) also obtained a higher carcass weight (16 kg) in the lambs on herb-clover mixture. Fraser and Rowarth (1996) obtained greater carcass weights by feeding pure swards of plantain, chicory and white clover and Speijers et al. (2004) by feeding red clover. Therefore, the present results in this experiment and that of Golding et al. (2011) indicate that farmers can utilize herb-clover mixtures to increase carcass weights. Means followed by different superscripts (a,b,c) within a row and year were significantly different (P < 0.05). Means followed by different superscripts (x,y,z) within a column and year were significantly different (P < 0.05). * No lambs present.

Table4. Effect of herbage treatment on LWG of lambs within each of the five study periods (winter, early spring, late spring, summer and autumn) (mean ± SE)
New Zealand lamb prices are determined using both GR tissue depth measurements and carcass weights (Kirton et al., 1984;Litherland et al., 2010). Mean GR tissue depth measurements in the lambs on the Pasture mixture were 5.2 mm and 5.8 mm in the year one and year two respectively. In contrast, lambs on both Plantain and Chicory mixtures had approximately 8.0 mm GR tissue depths in both years obtaining higher prices compared to the lambs on the Pasture mixture. Hence there is a higher potential for higher income from the lambs reared on herb-clover mixtures.

Variation of apparent carcass weight production per ha
Apparent carcass weight production per ha for each herbage treatment was calculated by taking the difference between total carcass weight production per ha per treatment at slaughter and estimated carcass weight production at day one (D 1 ) per ha per treatment.
Estimated carcass weight production at D 1 was assumed to be 40% of D 1 live weight (Kirton et al., 1984) for all lambs. Overall in year one, Plantain mixture had the highest total apparent carcass weight production per ha than the Chicory mixture (Table 6). However, during year two the Chicory mixture had the highest total carcass weight production per ha. During both years, Pasture mixture had the lowest total carcass weight production per ha. According to Table 6 herb-clover mixtures of plantain, chicory, white-and red-clover produce more lamb meat per ha than the ryegrass/white clover Pasture mixture from early spring to autumn period.

Annual Feed Conversion Ratio (FCR) and Efficiency of Herbage Utilization (EHU) of herbage treatments
Both Plantain and Chicory mixtures had lower (P < 0.05) FCR than Pasture mixture during both years (Table 7). Meyer and Garrett, (1967) explained Efficiency of Herbage Utilization (EHU) as the measurement of an animal's growth and maintenance in proportion to feed intake. Lambs on the Plantain and Chicory mixtures expressed greater performances utilising herbage more efficiently than the lambs on the Pasture mixture. This is also supported by the lower FCR values and higher herbage quality values in the herb-clover mixtures.
During the year two (2012/2013) summer and autumn periods there was a drought prevailed across the study area directly affecting herbage growth (Beef+Lamb New Zealand, 2014). In the year two summer and autumn periods, EHU in the Chicory mixture was greater than the Plantain mixture. This indicates that during dry summer and autumn periods, Chicory mixture is more efficient than the Plantain mixture. Even though the botanical composition data was not discussed in the present paper, it was observed that the plantain and white clover species composition drastically decreased after late spring in the Plantain mixture due to the effect of drought prevailed in the area in the year two. As a result Plantain mixture had a lower stocking rate than the Chicory mixture.
Overall lambs in the Plantain and Chicory mixtures had similar yet, greater live weight gains and carcass weights during most of the periods compared to the Pasture mixture. Hence, the herb-clover mixtures can be used by farmers to increase lamb growth rates over the early spring to autumn period. Means followed by different superscripts (a,b,c) within rows and years indicate means that were significantly different (P < 0.05). 1 Excluding winter data.

CONCLUSION
Both Plantain and Chicory mixtures produced greater carcass weights and a higher LWG compared to the Pasture mixture. Therefore, herb-clover mixtures can be used to improve lamb production compared to the ryegrass/white clover sward mixture over the early spring to autumn period in the Manawatu area, New Zealand and also in other areas having similar weather conditions.

ACKNOWLEDGEMENT
The authors acknowledge the International Sheep Research Centre, Massey University and the National Research Centre for Growth and Development, New Zealand for funding this research.