SRS Merinos have more lambs and rear more lambs

James Watts

SRS Merinos are plain bodied and very fertile sheep. There is a strong bond between the ewe and its lamb, so necessary for survival and growth of the lamb.

When you have bred robust and plain bodied ewes, you have secured the key profit drivers for a Merino breeding enterprise, namely:

  • high numbers of lambs weaned at excellent growth rates
  • very few lambs lost
  • quick recovery of the body condition of the ewes following lambing and lactation
  • low to nil feeding costs
  • excellent processing wool

SRS Merino rear a lot of lambs , on average, 120 to 130 % of lambs, compared with 75 % to 85 % in thick skinned Merino flocks.

Identifying Merino ewes which rear multiple lambs every time.

We focus on breeding Merino ewes that rear twins and triplets every year. These ewes are plain bodied, open faced, long eared and have high rumps and correspondingly, excellent breeding values for body muscle and fat reserves.

These ewes are of great interest to us. They are the key profit drivers for Merino breeding enterprises. In the SRS Merino studs, we prize these ewes as dams to breed replacement sires and to provide sale rams that will lift profit for commercial Merino flocks.

The visible traits in these ewes that explain this important outcome are:

  • plain bodies, not just one sheep but all of them.
  • great milking capacity to nurture the lambs.
  • an alert but calm temperament.

 

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Merino lambs must survive

Take a long and hard look at the graph (Figure 1) below.

It shows the survival rate of Merino lambs from pregnancy scanning at day 80 of pregnancy through to weaning of the lambs at 5 months of age.

 

Firstly, note the unacceptable result for the Australian Merino industry. Only 59 % of the foetal lambs alive at day 80 of the 150 day gestation of the ewe are reared.

Now look at the fantastic weaning results for the Karbullah SRS Poll Merinos of Mark , Vicki and Luke Murphy in the tough environment of south western Queensland. Most lambs survive. The surviving progeny of the different Merino sires is as high as 95.5 % for the ram 12517 with most sires doing better than 88 %.

Also note that Merino rams bred by other SRS Poll Merino studs, namely the Parkdale ram 1395 from the Mudford family at Dubbo, New South Wales, the Well Gully ram 4343 from Errol and Candy Brumpton at Mitchell in central western Queensland, another very tough environment, and the Boxleigh Park ram 1324 of Hugh and Mardi Taylor at Wellington, New South Wales, and used at Karbullah in the 2015 joining, have all done exceedingly well with 91 % or more of the ram’s progeny being reared.

In 2008, Mark and Vicki Murphy, Karbullah Poll Merino Stud, discovered that most lambs survive when sired by rams with high breeding values for fat cover and eye muscle depth (see Table 1 below).

Lamb survival was about 20 % lower when sired by rams with low breeding values for fat and muscle.

Table 1.

Sire

Fat cover breeding value

Eye muscle breeding value

Number of lambs born

% lambs weaned

 

High fat and muscle sires:

     

A

0.9

1.6

41

100

 

B

0.7

1.6

41

97

 

C

0.9

1.6

40

97

 

D

1.0

2.0

72

96

 

E

1.2

0.8

64

95

 

F

0.9

0.7

54

85

 

Low fat and muscle sires:

     

G

0.1

- 0.8

35

88

 

H

  • 0.8
  • 1.0

73

79

 

I

0.4

0.0

46

79

 

J

  • 0.9

-1.9

57

77

 

Thick skinned Merinos have low fertility

Thick skinned (wrinkly) Merino sheep have fewer lambs and lose more lambs.

Thick skinned Merino sheep predominate throughout the Australian flock. In addition to being mulesed, thick skinned sheep have fewer lambs, and lose more lambs, than plain bodied Merino sheep.

These facts have been reported repeatedly over the years by Australian researchers; see:

  • Young, S.S.Y., Turner, Helen Newton, and Dolling, C.H.S. (1963). Selection for fertility in Australian Merino sheep. Australian Journal of Agricultural Research 14:460.
  • Dun, R.B. (1964). Skin folds and Merino breeding. 1. The net reproductive rates of flocks selected for and against skin fold. Australian Journal of Experimental Agriculture and Animal Husbandry 4: 376.
  • Fels, H.W. (1964). The association between neck wrinkle and fertility in Merino ewes in south-western Australia. Australian Journal of Experimental Agriculture and Animal Husbandry 4: 121.
  • Dun, R.B. and Hamilton B.A., (1965). Skin fold and Merino breeding. 2. The relative influence of the ram and the ewe on fertility and perinatal lamb mortality in flocks selected for and against skin fold. Australian Journal of Experimental Agriculture and Animal Husbandry, 5 (18): 236-242.
  • McGuirk, B.J. (1969) Australian Journal of Experimental Agriculture and Animal Husbandry, 9 (37), 147-150 reported on the Merino sheep selected for skin wrinkle, averaged over twelve joinings (1951 to 1963), 10 % less lambs than Merino sheep selected for plain bodies.

In 14 Merino flocks throughout New South Wales, plain bodied Merino sheep were shown to have at least 15 % more lambs than wrinkly Merino sheep (Drinan, J.P. and Dun, R.B. (1965), Australian Journal of Experimental Agriculture and Animal Husbandry, 5 (19), 345-352).