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Registro Completo |
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Biblioteca(s): |
Embrapa Caprinos e Ovinos. |
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Data corrente: |
01/08/1992 |
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Data da última atualização: |
16/11/2023 |
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Autoria: |
KENNEDY, J. P.; AULDIST, I. H.; POPOVIC, P. G.; REYNOLDS, J. A. |
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Título: |
Reproduction rate of Merino sheep in arid N. S. W. |
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Ano de publicação: |
1976 |
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Fonte/Imprenta: |
Proceedings Australian Society Animal Production, v. 11, p. 149-151, 1976. |
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Idioma: |
Inglês |
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Conteúdo: |
Abstract: The components of reproduction were analysed from data collected over four years at Fowlers Gap Station, Broken Hill. Joining in April was superior to joining in January, June or November. The most common causes of reproductive wastage were failure of mated ewes to lamb and lamb and weaner mortality. I. INTRODUCTION Chudleigh (1971) commented that a paucity of data on reproductive performance of sheep in the arid West Darling region of N.S.W. made it difficult to devise management plans for flocks in the region. This study was designed to correct this deficiency and to develop more efficient and Our specific objective productive management procedures. was to identify the factors which contribute to reproductive wastage and to suggest methods of reducing the wastage. II. MATERIALS AND METHODS The experiment was conducted at Fowlers Gap Arid Zone Research Station, 100 km north of Broken Hill. The climate is dry with hot summers and mild winters and an average annual rainfall of 195 mm. Rainfall for the years 1971, 1972) 1973 and 1974 was 318 mm, 110 mm, 395 mm and 629 mm. Merino ewes of the South Australian strain have been joined in groups of 80 to 100 ewes at four different times each year since 1971. Joinings continued for 51 to 56 days with three merino rams in a 415 ha paddock. Sire Sine crayon marks on ewes were recorded at 17 day intervals during joining. Shortly before lambing commenced pregnancy diagnosis was made with the aid of an ultrasonic pregnancy tester. Ewes, branded with identifying numerals, lambed in a 605 ha Lambing paddock and were inspected daily with binoculars. date and litter size were recorded. At lamb marking, ewes were classified as lactating, lambed but not lactating, and not lambed. Lambs were weaned 10 weeks later and the ' survival of ewe lambs until they reached 16 months old was measured. From the data which were collected the components of reproduction rate were determined by the method of Turner (1968). * School of Wool and Pastoral Sciences, The University of N.S.W., Kensington, N.S.W. 149 III. RESULTS TABLE 1 Means (&SE) of 4 years data of components of reproduction rate of merino sheep Failure to mate was an important cause of reproductive wastage in June and November, 1972 (13.9% and 17.1% of ewes, respectively) presumably because feed conditions deteriorated throughout 1972, due to low rainfall. By contrast, flooding in January, 1974 contributed to mortality of 55.3% of ewes joined in November, 1973 and consequently depressed the proportion of mated ewes which lambed in this group. The exceptional rainfall in 1974 was accompanied by episodes of serious blowfly strike which contributed to mortality between mating and lambing in ewes joined in June and November I. (20.0% and l7.2%, respectively) and during lambing in ewes joined in April and June (18.6% and 16.7%, respectively). The proportion of lambs born per ewe lambing was estimated from the records of twinning rate collected during paddock observations and is subject to error since 13% of lambing ewes had no records of litter size. Lamb survival from birth to marking also is subject to the same errors since it is based on an estimate of the number of lambs born. IV. DISCUSSION This analysis indicates that the most common and serious causes of reproductive wastage were failure of mated ewes to lamb, lamb mortality between birth and marking and mortality of young ewes between weaning and 16 months of age. In some years mortality of ewes before and during lambing was substantial. 150 In the great majority of flocks in this region joining commences between October and March (Chudleigh 1971) however our results reveal that a much better reproduction An objection raised by rate followed joining in April. pastoralists to the adoption of autumn joining is the likelihood of flystrike in lambing ewes and in marked and mulesed lambs. This was serious in our study only in 1974 when rainfhll was exceptionally high. In arid areas where management is extensive it is unlikely that adoption of procedures to reduce lamb mortality will be economically feasible. It may be possible to reduce the proportion of mated ewes which fail to lamb by extending the joining period beyond the customary eight weeks and by attention to ram fertility. Selection to increase twinning rate appears to offer scope for increasing reproduction rate. Seasonal conditions were better than average in three of the four years of study which may limit the applicability of the results. The experiments are continuing and in the long-term a more normal range of seasonal conditions should be encountered. MenosAbstract: The components of reproduction were analysed from data collected over four years at Fowlers Gap Station, Broken Hill. Joining in April was superior to joining in January, June or November. The most common causes of reproductive wastage were failure of mated ewes to lamb and lamb and weaner mortality. I. INTRODUCTION Chudleigh (1971) commented that a paucity of data on reproductive performance of sheep in the arid West Darling region of N.S.W. made it difficult to devise management plans for flocks in the region. This study was designed to correct this deficiency and to develop more efficient and Our specific objective productive management procedures. was to identify the factors which contribute to reproductive wastage and to suggest methods of reducing the wastage. II. MATERIALS AND METHODS The experiment was conducted at Fowlers Gap Arid Zone Research Station, 100 km north of Broken Hill. The climate is dry with hot summers and mild winters and an average annual rainfall of 195 mm. Rainfall for the years 1971, 1972) 1973 and 1974 was 318 mm, 110 mm, 395 mm and 629 mm. Merino ewes of the South Australian strain have been joined in groups of 80 to 100 ewes at four different times each year since 1971. Joinings continued for 51 to 56 days with three merino rams in a 415 ha paddock. Sire Sine crayon marks on ewes were recorded at 17 day intervals during joining. Shortly before lambing commenced pregnancy diagnosis was made with the aid of an ultrasonic pregnancy test... Mostrar Tudo |
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Palavras-Chave: |
Comportamento reprodutivo; Manejo reprodutivo. |
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Thesagro: |
Merino; Ovino; Reprodução. |
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Thesaurus Nal: |
Reproductive behavior; Reproductive performance; Sheep. |
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Categoria do assunto: |
L Ciência Animal e Produtos de Origem Animal |
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Marc: |
LEADER 05334naa a2200253 a 4500
001 1522035
005 2023-11-16
008 1976 bl uuuu u00u1 u #d
100 1 $aKENNEDY, J. P.
245 $aReproduction rate of Merino sheep in arid N. S. W.
260 $c1976
520 $aAbstract: The components of reproduction were analysed from data collected over four years at Fowlers Gap Station, Broken Hill. Joining in April was superior to joining in January, June or November. The most common causes of reproductive wastage were failure of mated ewes to lamb and lamb and weaner mortality. I. INTRODUCTION Chudleigh (1971) commented that a paucity of data on reproductive performance of sheep in the arid West Darling region of N.S.W. made it difficult to devise management plans for flocks in the region. This study was designed to correct this deficiency and to develop more efficient and Our specific objective productive management procedures. was to identify the factors which contribute to reproductive wastage and to suggest methods of reducing the wastage. II. MATERIALS AND METHODS The experiment was conducted at Fowlers Gap Arid Zone Research Station, 100 km north of Broken Hill. The climate is dry with hot summers and mild winters and an average annual rainfall of 195 mm. Rainfall for the years 1971, 1972) 1973 and 1974 was 318 mm, 110 mm, 395 mm and 629 mm. Merino ewes of the South Australian strain have been joined in groups of 80 to 100 ewes at four different times each year since 1971. Joinings continued for 51 to 56 days with three merino rams in a 415 ha paddock. Sire Sine crayon marks on ewes were recorded at 17 day intervals during joining. Shortly before lambing commenced pregnancy diagnosis was made with the aid of an ultrasonic pregnancy tester. Ewes, branded with identifying numerals, lambed in a 605 ha Lambing paddock and were inspected daily with binoculars. date and litter size were recorded. At lamb marking, ewes were classified as lactating, lambed but not lactating, and not lambed. Lambs were weaned 10 weeks later and the ' survival of ewe lambs until they reached 16 months old was measured. From the data which were collected the components of reproduction rate were determined by the method of Turner (1968). * School of Wool and Pastoral Sciences, The University of N.S.W., Kensington, N.S.W. 149 III. RESULTS TABLE 1 Means (&SE) of 4 years data of components of reproduction rate of merino sheep Failure to mate was an important cause of reproductive wastage in June and November, 1972 (13.9% and 17.1% of ewes, respectively) presumably because feed conditions deteriorated throughout 1972, due to low rainfall. By contrast, flooding in January, 1974 contributed to mortality of 55.3% of ewes joined in November, 1973 and consequently depressed the proportion of mated ewes which lambed in this group. The exceptional rainfall in 1974 was accompanied by episodes of serious blowfly strike which contributed to mortality between mating and lambing in ewes joined in June and November I. (20.0% and l7.2%, respectively) and during lambing in ewes joined in April and June (18.6% and 16.7%, respectively). The proportion of lambs born per ewe lambing was estimated from the records of twinning rate collected during paddock observations and is subject to error since 13% of lambing ewes had no records of litter size. Lamb survival from birth to marking also is subject to the same errors since it is based on an estimate of the number of lambs born. IV. DISCUSSION This analysis indicates that the most common and serious causes of reproductive wastage were failure of mated ewes to lamb, lamb mortality between birth and marking and mortality of young ewes between weaning and 16 months of age. In some years mortality of ewes before and during lambing was substantial. 150 In the great majority of flocks in this region joining commences between October and March (Chudleigh 1971) however our results reveal that a much better reproduction An objection raised by rate followed joining in April. pastoralists to the adoption of autumn joining is the likelihood of flystrike in lambing ewes and in marked and mulesed lambs. This was serious in our study only in 1974 when rainfhll was exceptionally high. In arid areas where management is extensive it is unlikely that adoption of procedures to reduce lamb mortality will be economically feasible. It may be possible to reduce the proportion of mated ewes which fail to lamb by extending the joining period beyond the customary eight weeks and by attention to ram fertility. Selection to increase twinning rate appears to offer scope for increasing reproduction rate. Seasonal conditions were better than average in three of the four years of study which may limit the applicability of the results. The experiments are continuing and in the long-term a more normal range of seasonal conditions should be encountered.
650 $aReproductive behavior
650 $aReproductive performance
650 $aSheep
650 $aMerino
650 $aOvino
650 $aReprodução
653 $aComportamento reprodutivo
653 $aManejo reprodutivo
700 1 $aAULDIST, I. H.
700 1 $aPOPOVIC, P. G.
700 1 $aREYNOLDS, J. A.
773 $tProceedings Australian Society Animal Production$gv. 11, p. 149-151, 1976.
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