Dynamics of morphology of myocardium in neonatal lambs

Perinatal lamb mortality remains a major economic and welfare concern in sheep farming with 80-90% of pre-weaning lamb losses occur in the immediate postnatal period (Haughey, 1993). One of the predominant factors in the death of neonatal lambs is failure of ewe-lamb bonding leading to delay or lack of sucking. Successful sucking requires the co-ordinated expression of appropriate behaviour from both the ewe and lamb. Previously we have demonstrated an interaction between ewe and lamb breed in the rate of successful sucking (Dwyer et al., 1996) with Blackface lambs having a higher rate than Suffolk lambs but also a higher rate with Suffolk ewes than with Blackface ewes. In the present study we investigated the role of ewe responses to lamb sucking attempts in determining the sucking success of neonatal lambs.

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Left and right ventricular myocardial morphometry in fetal, neonatal, and adult sheep

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1989.257.1.h1 ◽

1989 ◽

Vol 257 (1) ◽

pp. H1-H9 ◽

Cited By ~ 24

Author(s):

J. J. Smolich ◽

A. M. Walker ◽

G. R. Campbell ◽

T. M. Adamson

Keyword(s):

Right Ventricular ◽

Relative Size ◽

Perinatal Period ◽

Capillary Density ◽

Volume Density ◽

Late Gestation ◽

Adult Sheep ◽

Intercapillary Distance ◽

Neonatal Lambs ◽

Capillary Size

This study has examined left (LV) and right ventricular (RV) myocardial morphometry in perfusion-fixed hearts of late-gestation sheep fetuses, neonatal lambs, and adult sheep. During development, myocyte size, intercapillary distance, and myocyte myofibrillar and mitochondrial volume densities increased, whereas capillary density, the myocyte-to-capillary ratio, and the myocyte matrix volume density decreased. RV myocytes were larger than LV myocytes in cross section in fetuses and 4-day-old lambs. LV and RV myocytes were of similar size in 7-day-old lambs. LV and RV myocytes were of larger in older lambs and adult sheep. Differences between LV and RV myocyte volume densities of myofibrils, mitochondria, and matrix were also observed in fetuses and young lambs. As well, variation in capillary size and density was apparent between ventricles in the fetal and neonatal periods. We conclude that, in the sheep heart, 1) LV and RV morphometric differences exist during fetal and postnatal development, 2) fetal LV and RV myocardial morphometry is consistent with an RV dominance in utero, 3) rapid growth of LV and RV myocytes occurs in the perinatal period, and 4) the relative size of LV and RV myocytes does not reflect a postnatal LV dominance until between 1 and 4 wk after birth.

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Induction of maternal behaviour in non-pregnant, hormone-primed ewes

Animal Science ◽

10.1017/s1357729800008602 ◽

1997 ◽

Vol 65 (3) ◽

pp. 403-408 ◽

Cited By ~ 11

Author(s):

C. M. Dwyer ◽

A. B. Lawrence

Keyword(s):

Hormonal Treatment ◽

Hormone Treatment ◽

Maternal Behaviour ◽

Previous Exposure ◽

Foster Mothers ◽

Pregnant Sheep ◽

Neonatal Lambs

AbstractIt has been suggested that the induction of maternal behaviour in non-pregnant ewes by treatment with oestrogen and progesterone followed by artificial, mechanical vaginocervical stimulation (VCS), could be used to produce foster mothers for orphan or triplet lambs. To investigate the reliability of the technique, 46 non-pregnant sheep of two breeds (Suffolk (S) and Scottish Blackface (BF)) and two levels of experience (nulliparous (N) and multiparous (M)) were used. All ewes were given 6 weeks of treatment with vaginal sponges containing oestradiol and progesterone, followed by 2 min of VCS and exposure to a neonatal (< 2 days old) foster lamb. Plasma oestrogen and prolactin concentrations were significantly elevated by the hormonal treatment; prolactin was significantly higher in M ewes compared with N ewes (BFN = 91, SN = 107, BFM = 301, SM = 687 μg/l, P < 0·005). Significant udder development was seen in most ewes (proportionately 1·0 M v. 0·62 N, P = 0·01) and more M ewes produced milk than N ewes (0·67 v. 0·19, P < 0·005). No ewes showed maternal behaviour to the lamb from hormone treatment alone. After VCS, one of 26 N ewes and five of 12 M ewes expressed maternal behaviour. In the M ewes, significantly more S ewes were maternal than BF ewes (proportionately 0·75 SM v. 0·25 BFM, P < 0·05). It is concluded that the technique alone is not sufficiently reliable to be a useful fostering aid. It is suggested, however, that previous exposure to neonatal lambs, handling of ewes before testing and using newborn lambs, may be fruitful areas of investigation to improve the technique.

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Effect of abdominal distension on central and regional hemodynamics in neonatal lambs

Journal of Critical Care ◽

10.1016/0883-9441(87)90126-2 ◽

1987 ◽

Vol 2 (1) ◽

pp. 76

Author(s):

S.A. Masey ◽

R.C. Koehler ◽

J.R. Buck

Keyword(s):

Abdominal Distension ◽

Regional Hemodynamics ◽

Neonatal Lambs

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The polyunsaturated fatty acid status of foetal and neonatal ruminants

British Journal Of Nutrition ◽

10.1079/bjn19780011 ◽

1978 ◽

Vol 39 (1) ◽

pp. 53-59 ◽

Cited By ~ 5

Author(s):

E. Payne

Keyword(s):

Fatty Acid ◽

Soft Tissues ◽

Placental Transfer ◽

Total Concentration ◽

Young Animal ◽

Internal Standard ◽

Mature Animal ◽

Neonatal Lambs ◽

Total Body ◽

Total Pufa

1. Information on the fatty acid composition of tissues of foetal calves, neonatal lambs, deer and piglets reported by Payne (1978) has been quantified by the use of an internal standard during analysis, to give concentrations of total polyunsaturated fatty acids (PUFA) derived from linoleic acid (ω6) and linolenic acid (ω3) expressed on a per kg tissue basis. The total concentration of both acids (ω6+ω3) was similar in all tissues examined except brain. Because muscle, the main constituent of the soft tissues of young animals, contains about 40–50 % of the total body content of these acids, it is considered that muscle concentrations are a reflection of total body status of these acids.2. Concentrations in muscle of both ω6 derivatives and total PUFA were significantly lower in the neonatal lamb and foetal calf than in the mature animal whereas in pigs and deer the concentrations in the young animal were similar to those in the mature animal. Concentrations of ω6 derivatives and total PUFA in lambs were significantly lower than those in calves; the presence of ω3 derivatives reduced the level of significance for total PUFA. Again, total PUFA content did not differ significantly between the piglet and the young ruminants.3. There was a substantial placental transfer, with apparently a preferential transfer of ω3 derivatives.4. In brain the levels of ω3 acids were as high in the foetal and neonatal animals as in mature animals. The levels of ω6 acids were lower in young animals.5. Calculations of ω6 intake from milk showed that the total deficit of ω6 could be made up within a few days.6. It was concluded that the extent of deficiency of ω6 in young ruminants raised in a grazing situation, as in New Zealand, is marginal and any feeding to overcome this is unlikely to be of any benefit.

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