Enhanced reproductive performance of ewes given
a sustained-release multi-trace element/vitamin
ruminal bolus
R.G. Hemingway
*, J.J. Parkins, N.S. Ritchie
Department of Veterinary Clinical Studies, University of Glasgow, Veterinary School,Bearsden, Glasgow, UK
Accepted 7 May 2000
Abstract
A sustained-release multi-trace element/vitamin bolus has been devised for administration to ewes in advance of mating. Each bolus contained 5.3 g Cu, 50 mg Se, 90 mg Co, 100 mg I, 3.2 g Mn and 4.7 g Zn with 268103IU Vitamin A, 54103
IU Vitamin D and 800 IU Vitamin E. About 50% of each nutrient is released during the ®rst 6 weeks. Thereafter the release rate slows and over the remaining life of the bolus (about 6 months extending to lambing time) the daily release rates are about 15 mg Cu, 0.1 mg Se, 0.2 mg Co, 0.3 mg I, 9.4 mg Mn and 13 mg Zn with 775 IU Vitamin A, 156 IU Vitamin D and 2 IU Vitamin E. In one study the proportion of twins born to ewes given the bolus was very signi®cantly (P<0:001) higher than for the untreated ewes and greater than for those given a copper injection or copper oxide needles. In a second study the proportion of ewes given a bolus and having twin lambs was signi®cantly (P<0:01) greater than for untreated ewes and signi®cantly (P<0:05) fewer ewes were non-pregnant. In a third study, giving a bolus to shearling ewes tended (P0:06) to result in fewer non-pregnant animals than for those untreated. Blood copper and Vitamin B12concentrations and glutathione peroxidase activities were above normal values throughout.#2001 Elsevier Science B.V. All rights reserved.
Keywords:Ewes; Reproductive performance; Trace element/vitamin bolus supplementation; Blood copper; Blood glutathione peroxidase
1. Introduction
The critical role of trace elements in the fertility of ewes has been reviewed by Hidiroglou (1979). Both copper (Howell, 1968) and selenium (Hartley and Grant, 1961) inadequacies impair conception by reduced ova implantation, early embryonic loss and foetal death. Segerson and Ganapathy (1981) recorded
signi®cantly more fertilised ova, signi®cantly more uterine contractions and signi®cantly more ewes with large numbers of sperm attached to the zona pellucida due to improved sperm mobility when ewes of mar-ginal blood selenium status (0.05mg/ml) were given injections of 10 mg Se and 136 IU Vitamin E before mating. Godwin et al. (1970) reported signi®cant increases in lambing percentage when ewes with an initial low blood Se concentration (0.026mg/ml) were given oral supplements of 5 or 25 mg Se as sodium selenite or as a selenium/iron powdered metal bolus 1 month before lambing. Hill et al. (1969) have described a signi®cant copper/selenium
*Corresponding author. Tel.:44-1360-770044;
fax:44-1360-770711.
supplementation interaction resulting in an increased proportion of twins born where inadequacies (described as `marginal') of both elements occurred. Scales (1974) recorded that in three of four trials where Merino ewes were given orally 5 mg Se as sodium selenate approximately 17 days before mating the proportion of barren ewes was reduced by 17%. Cobalt insuf®ciency, by its detrimental effects on appetite and eventual body condition score, results in reductions in both oestrus activity and multiple ovulation. In an experimental situation where cobalt inadequacy was described as `marginal' because of absence of clinical signs, Fisher and MacPherson (1991) recorded that dietary cobalt supplementation from 16 days before mating resulted in fewer lamb losses due to abortion and probable reabsorption between scanning in mid-pregnancy and birth and signi®cantly fewer neonatal lamb deaths. Egan (1972) recorded signi®cant increases in lambing per-centage when ewes consuming herbage of marginal manganese and zinc status (about 45 mg Mn and about 20 mg Zn/kg dry matter) were additionally given orally 45 mg Mn and 20 mg Zn per day.
It is not possible to ensure appropriate and indivi-dually uniform consumption of trace elements and vitamins by groups of sheep and cattle at grass from mineral mixtures, molassed liquids or high density feedblocks (Hemingway, 1998). Earlier communica-tions by Lawson et al. (1990) have demonstrated that two trace element/vitamin boluses (`All-Trace', Agri-min Ltd. DN20 0SP UK) gave substantial sustained responses in glutathione peroxidase activity (GSHPx) in beef cows together with a signi®cant increase in conception rate and reduction in calving spread (Allan et al., 1993). Signi®cant sustained responses in blood copper concentration have been reported in both growing cattle and beef cows at grass by Parkins et al. (1994). Smaller sized boluses (55 mm length18 mm diameter) have been demonstrated to give sustained responses in blood copper concen-trations and GSHPx activities in studies with both suckling beef calves at grazing and housed dairy-bred calves for over 4 months (Hemingway et al., 1997). Two boluses are required as a treatment since nutrient release is controlled by a combination of solution and mutual erosion in the reticulum.
The principle and construction of the multiple trace element/vitamin bolus system for calves (Hemingway
et al., 1997) has been modi®ed for use as a single bolus system suitable for ewes (`Small-Trace', Agrimin Ltd. DN20 0SP) and has now been evaluated in studies with three ¯ocks of upland ewes to assess the effect of such supplementation on the number of lambs born per ewe
2. Materials and methods
2.1. Bolus construction and release rate evaluations
The bolus is composed of copper oxide powder, sodium selenite, cobalt sulphate, potassium iodide, manganese sulphate, zinc oxide and zinc sulphate with Vitamins A, D3and E. The 30 g active matrix contains
(mg) Cu 5300, Se 50, Co 90, I 100, Mn 3250, Zn 4700 with (IU) Vitamins A 268,000, D354,000 and E 800.
There is a small base weight within each bolus to increase the density. An additional weight is tempora-rily attached with a water-soluble ®xative to the upper (¯at) exposed end of the otherwise completely poly-mer-coated cylinder. This further increases the initial density and increases the rate of movement of the bolus to the reticulum immediately following admin-istration. It rapidly separates from the bolus and then acts as a `grinder'.
Evaluations of bolus matrix release rates have been made in adult rumen-cannulated cows and slaughtered cast ewes (Ritchie et al., 1997) and in growing sheep (Hemingway et al., 1997). About half (15 g) of the active matrix weight (30 g) is released in the ®rst 6 weeks (about 2700 mg Cu, 26 mg Se and 46 mg Co) and with proportional amounts of the other contained nutrients. Thereafter, the daily release rate reduces and the mean amounts eroded each day from 6 weeks to an estimated 7 months are (mg) Cu 15, Se 0.14, Co 0.24, I 0.28, Mn 9.2, Zn 13.3 with Vitamins A 762 IU, D3163
2.2. Studies with ¯ocks of upland ewes
Studies with a single `Small-Trace' bolus were conducted in three separate upland ¯ocks in situations where one or more trace element inadequacies (copper, selenium and/or cobalt) were known to be present and where various forms of individual supplementation were regularly advised as either injections, oral solutions or by other means. In each study, blood samples were obtained as a routine diagnostic metabolic pro®le procedure in view of the previous clinical histories, initially on the day that `Small-Trace' and other various supplements were given (in November, about 10 days before the intro-duction of the rams) and again in late pregnancy in March (when the ewes were scanned to determine pregnancy status). These were taken on each occasion from a random 10 ewes in each larger group in each study and analysed for copper, GSHPx activity and Vitamin B12.
Copper was determined by atomic absorption spec-troscopy and GSHPx activity (Units/ml red cells at 378C) by a modi®cation of the method of Paglia and Valentine (1967) using a Ransel kit (Randox Labora-tories). Vitamin B12was assessed by a modi®cation of
the method of Taylor and Greer (1982). The numbers of lambs born per treatment group was examined by chi-squared analysis and the mean assessments of blood parameters were evaluated by analysis of variance.
2.2.1. Study 1
This was conducted on the same farm where pre-vious studies (Parkins et al., 1994; Hemingway et al., 1997) had demonstrated sustained incremental responses in blood Cu concentrations and GSHPx activities in beef cows and calves, respectively, fol-lowing supplementation with two larger-sized `All-Trace' boluses. A ¯ock of 120 Blackface ewes were randomly allocated to four treatment groups each of 30 ewes. Group 1 ewes were given a single `Small-Trace' bolus (B); Group 2 ewes were given a copper injection (I) (`Coppaclear', providing 12.5 mg Cu as copper heptonate, Crown Veterinary Pharmaceuticals Ltd.); Group 3 ewes were given a capsule containing copper oxide needles (N) (`Copporal' containing 4 g CuO and providing 3.4 g Cu, Beecham Animal Health Ltd.) and Group 4 ewes were untreated (U). The
groups of ewes grazed together and were with Border Leicester rams for 8 weeks.
2.2.2. Study 2
This was undertaken on a farm where both copper and selenium inadequacies were found occasionally in both ewes and beef cows. Blackface ewes were ran-domly allocated to two dietary treatments. Ninety six ewes were given a single `Small-Trace' bolus (B) and 118 ewes were unsupplemented (U). Both groups grazed together. Bluefaced Leicester rams were with the ewes from 10 days later for a period of 8 weeks.
2.2.3. Study 3
This study was conducted with Swaledale shearling ewes. The younger ewes on this farm had a history of inadequate reproductive performance. The overall management and general nutrition were good and trace element inadequacies were suspected from pre-vious studies but supplementation had generally been from mid-pregnancy onwards. One group of 40 ewes was given a single `Small-Trace' bolus (B) and a further comparable group of 40 ewes was untreated (U). Additionally, 2 weeks earlier all the ewes had been given an oral drench which supplied 10 mg Co, 5 mg Se, 500,000 IU Vitamin A, 12,000 IU Vitamin D3, 50 mg Vitamin B1 and 750 mg Vitamin B12.
Rams were with the ewes for three complete oestrus cycles.
3. Results
The normal range for blood copper concentrations for sheep is 9±15mmol/l (Suttle, 1994) and lower values of 3.0±4.5mmol/l are commonly found in clinically affected sheep when accompanied by reduced liver copper contents (Whitelaw et al., 1979). Anderson et al. (1979) have described blood GSHPx activities (U/ml red cells at 378C) and their equivalent plasma selenium concentrations for sheep as de®cient, <18 U GSHPx and <0.05mg Se/ml; low/ marginal, 30 U GSHPx and <0.075mg Se/ml; mar-ginal, 40 U GSHPx and <0.11mg Se/ml and adequate, >40 U GSHPx and >0.11mg Se/ml.
remained under veterinary control and all, including the untreated ewes, were in good health throughout with normal blood values and no inter-current disease. In the event, all Vitamin B12 analyses from all the
sampled ewes on both occasions were adequate and above 250 ng/l (and with the majority >1000 ng/l) and, in the interests of brevity of presentation, are not further discussed here.
3.1. Study 1
Very signi®cantly (chi-squared13:3,P<0:001)
more twins were born to the ewes given the bolus and to those given the copper injection (chi-squared4:8, P<0:05) than were born to the untreated ewes
(Table 1). The increase in the proportion of ewes given the copper oxide needles and having twins approached signi®cance (chi-squared3:15, P
0:07). There were also more twins born to the ewes
given a bolus than to those given copper oxide needles (chi-squared3:93,P<0:05). The overall lambing
percentages (lambs born per 100 ewes mated) were 160 (ruminal bolus), 140 (copper injection), 130 (copper oxide needles) and 100 (untreated). Mean blood copper concentrations and GSHPx activities for all groups on both sampling occasions were always well above the critical levels (9mmol Cu/l and 18 U/ml red cells) and both would be considered as fully adequate. Only the ruminal bolus treatment signi®cantly (P<0:001) increased mean GSHPx
activity.
3.2. Study 2
Signi®cantly (chi-squared6:86,P<0:01) more
twin lambs were born to the ewes given the bolus than to the untreated ewes. There were also signi®cantly (chi-squared3:99,P<0:05) more barren ewes that
were untreated. The overall lambing percentages were 152 for the bolus-supplemented ewes and 124 for the untreated ewes. Mean blood copper concentrations were adequate throughout but by March a signi®cant difference between mean values had developed with the concentration for the untreated ewes (10.3mmol/l) approaching the lower limit of the normal range. Mean blood GSHPx activity was markedly and signi®cantly enhanced by the bolus treatment (Table 2).
Table 1
Study 1: the number of lambs born, the mean concentrations of copper (mmol/l) and the mean glutathione peroxidase activities (GSHPx units/ ml red cells) in the blood of the ewes
Bolus Injection Needles Untreated S.E.D. P
(B) (I) (N) (U)
Twins 19 13 11 5 ± ±
Singles 10 16 17 23 ± ±
Non-pregnant 1 1 2 2 ± ±
Blood Cu
November 13.2 13.0 15.5 14.1 0.94 NSa
March 15.2 13.1 11.1 13.5 1.89 NS
GSHPx
November 122 96 113 105 18.4 NS
March 188 121 98 120 8.5 B>I;N;U<0:001
aNSP> 0.05.
Table 2
Study 2: the number of lambs born, the mean concentrations of copper (mmol/l) and the mean glutathione peroxidase activities (GSHPx, units/ml red cells) in the blood of the ewes
Bolus Untreated S.E.D. P
Twins 54 42 ± ±
Singles 38 63 ± ±
Non-pregnant 4 13 ± ±
Blood Cu
November 14.8 13.3 0.96 NSa
March 15.1 10.3 1.59 <0.05
GSHPx
November 42 47 9.9 NS
March 180 64 21.6 <0.001
3.3. Study 3
Nine sets of twins were born to the 40 ewes in each group. Nine of the 40 ewes given the bolus were found to be non-pregnant compared with 17 of the 40 untreated ewes. This difference failed to reach sig-ni®cance atP<0:05 (chi-squared 3.84 required), but
with a chi-squared value of 3.65 was signi®cant at P0:06. The overall lambing percentages were 100 for the ewes given a bolus and 80 for the untreated ewes. Mean blood copper concentrations and GSHPx activities were always fully adequate (Table 3).
4. Discussion and conclusions
The overall mean blood copper concentration for the three studies combined (30 ewes given the bolus and 30 untreated ewes) was signi®cantly (P<0:01)
higher in March than that for the untreated ewes (Table 4). Mean blood GSHPx activities were also signi®cantly greater (P<0:001) in March as a result of bolus treatment. It is recognised that neither blood copper concentrations nor GSHPx activities would be considered as inadequate at any stage for any of the three studies.
In Study 1, the signi®cantly higher lambing per-centage of the ewes given the bolus compared to those given the copper injection or the copper oxide needles above that for the untreated ewes must be due to the inclusion of some other trace element (than copper) or vitamin in the bolus. This was considered most likely
to be attributed to the selenium content. Mudd and Mackie (1973) reported that a combined intra-mus-cular injection of 6 mg selenium with 272 IU Vitamin E given 4 weeks before mating to hill ewes at ®ve sites in Scotland signi®cantly (P<0:001) increased the
proportion of ewes with multiple births from 10.1 to 29.6%. Mean initial blood selenium concentrations were normal (0.09 S.D., 0.025 mg/l). Earlier in New Zealand, Hartley and Grant (1961), Hartley (1963) and Andrews et al. (1968) gave a similar injection to ewes before mating and variously reported increases in lambing percentage from 74 to 118, from 25 to 90 and from 80 to 120. The ewes were in fair to good condition and the difference was due to both failure to conceive and early embryonic death at 3±4 weeks post conception.
In Study 2, as a result of two mechanisms, the lambing percentage of the ewes given the bolus was 152 compared with 124% for the untreated ewes. The bolus treatment increased the number of twins born and at the same time reduced the proportion of barren ewes. In Study 3, the bolus treatment markedly, but just failing signi®cance (P0:06), reduced the num-ber of non-pregnant shearling ewes. The contrasting lambing percentages were 80 (untreated) and 100 (bolus treatment). The bolus treatment resulted in a signi®cantly higher mean GSHPx activity in March than that for the untreated ewes (Table 3). This tendency to an improved lambing performance was found in spite of the fact that all the ewes in Study 3 Table 3
Study 3: the number of lambs born, the mean concentrations of copper (mmol/l) and the mean glutathione peroxidase activities (GSHPx, units/ml red cells) in the blood of the ewes
Bolus Untreated S.E.D. P
Twins 9 9 ± ±
Singles 22 14 ± ±
Non-pregnant 9 17 ± ±
Blood Cu
November 13.4 12.1 1.20 NSa
March 16.9 15.8 0.46 NS
GSHPx
November 87 84 9.7 NS
March 170 130 15.9 <0.05
aNSP> 0.05.
Table 4
Studies 1±3 combined: mean blood copper (mmol/l) and mean GSHPx activities (units/ml red cells) for 30 ewes per each combined group
Bolus Untreated Pooled S.E.D.
P
Copper
November 13.8 13.2 0.51 NSa
March 15.7 13.2 0.84 <0.01
Pooled S.E.D. 0.98 0.98 ± ±
P NS NS ± ±
GSHPx
November 84 79 7.7 NS
March 179 105 9.4 < 0.001
Pooled S.E.D. 12.2 12.2 ± ±
P <0.001 <0.01
had been given an oral drench containing cobalt, selenium and Vitamins A, B and D about 1 month before mating.
It is concluded that the multi-trace element/vitamin bolus given to ewes before mating signi®cantly increased the lambing percentage of upland ewes from the existing situation where 80±120 lambs were born to 100 ewes mated although blood copper and Vitamin B12 concentrations and GSHPx activities for the
untreated ewes were considerably higher than the minimum of accepted normal ranges throughout.
Acknowledgements
The Cu and GSHPx determinations were under-taken by C. Cameron. Vitamin B12 determinations
were undertaken at the Veterinary Investigation Cen-tres at Penrith and the Scottish Agricultural College at Edinburgh. These studies would not have been pos-sible without the full interest and co-operation of the farmers (Messrs A. Bain, J. Fraser and D. Lawton) and their veterinary surgeons (Messrs A. McInness, M. Shanks and M. Colston).
References
Allan, C.L., Hemingway, R.G., Parkins, J.J., 1993. Improved reproductive performance in cattle dosed with trace element/ vitamin boluses. Vet. Rec. 132, 463±464.
Anderson, P.H., Berrett, S., Patterson, D.S.P., 1979. The biological selenium status of livestock in Britain as indicated by sheep erythrocyte glutathione peroxidase activity. Vet. Rec. 104, 235± 238.
Andrews, E.D., Hartley, W.J., Grant, A.B., 1968. Selenium-responsive diseases of animals in New Zealand. N.Z. Vet. J. 16, 3±17.
Egan, A.R., 1972. Reproduction responses to supplementary zinc and manganese in grazing Dorset Horn ewes. Aust. J. Exp. Agric. Anim. Husb. 12, 131±135.
Fisher, G.E.J., MacPherson, A., 1991. The effect of cobalt de®ciency in the pregnant ewe on reproductive performance and lamb viability. Res. Vet. Sci. 50, 319±327.
Godwin, K.O., Kuchel, R.E., Buckley, R.A., 1970. The effect of selenium on infertility in ewes grazing improved pastures. Aust. J. Exp. Anim. Husb. 10, 672±678.
Hartley, W.J., 1963. Selenium and ewe fertility. Proc. N. Z. Soc. Anim. Prod. 23, 20±27.
Hartley, E.D., Grant, A.B., 1961. A review of selenium responsive diseases in New Zealand livestock. Fed. Proc. 20, 679±688.
Hemingway, R.G., 1998. Supplying trace elements to cattle. Feedmix 6 (4), 8±10.
Hemingway, R.G., Parkins, J.J., Ritchie, N.S., 1997. Copper and glutathione peroxidase (GSHPx) responses in lambs given a sustained-release rumen bolus. Proc. Nutr. Soc. 56, 305A. Hidiroglou, M., 1979. Trace element de®ciencies and fertility in
ruminants: a review. J. Dairy Sci. 62, 1195±1206.
Hill, M.K., Walker, S.D., Taylor, A.G., 1969. Effects of `marginal' de®ciencies of copper and selenium on growth and productivity in sheep. N.Z. J. Agric. Res. 12, 261±270.
Howell, J.McC., 1968. The effect of experimental copper de®ciency on growth, reproduction and haemopoiesis in the sheep. Vet. Rec. 83, 226±227.
Lawson, D.C., Ritchie, N.S., Parkins, J.J., Hemingway, R.G., Gresham, H.R., 1990. Use of a sustained-release bolus for enhancing the selenium status of cattle. Vet. Rec. 127, 67±68.
Mudd, A.J., Mackie, I.L., 1973. The in¯uence of Vitamin E and selenium on ewe proli®cacy. Vet. Rec. 93, 197±199. Paglia, D.C., Valentine, W.N., 1967. Studies on the quantitative and
qualitative characteristics of erythrocyte glutathione peroxi-dase. J. Lab. Clin. Med. 70, 158±169.
Parkins, J.J., Hemingway, R.G., Lawson, D.C., Ritchie, N.S., 1994. The effectiveness of copper oxide powder as a component of a sustained-release multi-trace element and vitamin rumen bolus system for cattle. Br. Vet. J. 150, 547±553.
Ritchie, N.S., Hemingway, R.G., Parkins, J.J., 1997. A sustained-release multi-trace element/vitamin rumen bolus for ewes. Proc. Br. Soc. Anim. Sci. 154.
Scales, G.H., 1974. Reproductive performance of Merino ewes dosed with selenium prior to mating. Proc. N. Z. Soc. Anim. Prod. 34, 103±113.
Segerson, E.C., Ganapathy, S.N., 1981. Fertilisation of ova in selenium/Vitamin E-treated ewes maintained on two planes of nutrition. J. Anim. Sci. 51, 386±394.
Suttle, N.F., 1994. Meeting the copper requirements of ruminants. In: Garnesworthy, P.C., Cole, D.J.A. (Eds.), Recent Advances in Animal Nutrition. Nottingham University Press, Nottingham, UK, pp. 173±188.
Taylor, C.N., Greer, J.C., 1982. Further studies of radio-assay techniques for the estimation of Vitamin B12in ovine serum.
Medium 15, 15±18.
