Proportion of rams and the condition of ewe lambs at joining influences their breeding performance

2010 ◽  
Vol 50 (6) ◽  
pp. 454 ◽  
Author(s):  
P. R. Kenyon ◽  
S. T. Morris ◽  
D. M. West
Keyword(s):  
Reproductive Performance ◽  
Pregnancy Rates ◽  
Breeding Period ◽  
Breeding Performance ◽  
Ewe Lambs ◽  
Condition Score ◽  
Ewe Lamb ◽  
In Pregnancy

The aim of the present study was to examine the effects of ram : ewe lamb ratio and condition score on the reproductive performance of ewe lambs. In the 2007 study, ewe lambs were bred with rams, at ram : ewe lamb ratios of 1 : 30, 1 : 50, 1 : 75 or 1 : 100. In the 2008 study, ewe lambs were bred at ratios of 1 : 31, 1 : 50, 1 : 75 or 1 : 100. Ewe lambs were bred over two 17-day periods. In both studies, ewe lambs bred in the first 17 days of breeding only were heavier (P < 0.05) than those bred in the second 17-day period only, and those ewe lambs diagnosed as twin-bearing were heavier (P < 0.05) than their single-bearing counterparts. Ewe lambs with a condition score of 2.5 or greater were more likely (P < 0.05) to be bred, and be pregnant, in the first 17 days of breeding than those of condition score 1.5 or 2.0. Over the entire 34-day breeding period, ewe lambs with a condition score of 2.5 or greater had higher (P < 0.05) pregnancy rates than those with a condition score of 2.0, which in turn had higher rates than those of 1.5. In the 2007 study, after 34 days of breeding, there were no differences (P > 0.05) in pregnancy rates among the different ram : ewe lamb ratios. While in the 2008 study, pregnancy rates after 34 days were greater (P < 0.05) in the 1 : 50 compared with both the 1 : 75 and 1 : 100 treatments. Pregnancy rates of 1 : 31 ewe lambs were greater (P < 0.05) than those of 1 : 75 ewe lambs. In the 2007 study, pregnancy rates of ewe lambs to the first 17 days of breeding were greater (P < 0.05) for those bred at a ratio of 1 : 75 than for those bred at 1 : 50, and tended to be greater (P = 0.08) than for those bred at 1 : 100. In addition, those bred at a ratio of 1 : 30 tended to have higher pregnancy rates (P = 0.07) than those bred at 1 : 50. While in the 2008 study, pregnancy rates to the first 17 days of breeding were greatest (P < 0.05) in the 1 : 31 and 1 : 50 treatments groups. In conclusion, the results of the present study indicate that achieving greater liveweights and higher condition scores of ewe lambs at breeding will increase the proportion pregnant, especially early in the breeding period. The data also suggest, in combination with the results of previous research, that farmers should consider utilising ram : ewe lamb ratios lower than 1 : 100, although further studies are warranted.

Effect of timing of exposure to vasectomised rams and ewe lamb body condition score on the breeding performance of ewe lambs

2012 ◽  
Vol 52 (7) ◽  
pp. 471 ◽  
Author(s):  
L. M. Cave ◽  
P. R. Kenyon ◽  
S. T. Morris
Keyword(s):  
Body Condition ◽  
Reproductive Performance ◽  
Body Condition Score ◽  
Breeding Period ◽  
Breeding Performance ◽  
Ewe Lambs ◽  
Percentage Points ◽  
Condition Score ◽  
Ewe Lamb ◽  
Timing Of Exposure

The aims of this study were to examine the effects of exposing Romney ewe lambs (8–9 months of age) to vasectomised rams across three studies in the February–March period and to determine the influence of body condition score (CS) in two of the studies on their reproductive performance. In all studies, ewe lambs exposed to vasectomised rams had greater (P < 0.05) conception rates to the first 17 days of breeding by 6–12 percentage points. However, Studies 2 and 3 indicated that exposing ewe lambs to vasectomised rams did not increase (P > 0.05) the percentage of ewe lambs conceiving over a 34-day breeding period, nor did it increase the number of fetuses per ewe lamb presented for breeding. The results of Study 1 suggest that there is a limit to how early in the year ewe lambs can be exposed to vasectomised rams. In Study 2, a greater (P < 0.05) percentage of Teased CS 2.0 or 2.5+ ewe lambs conceived during the first 17 days of breeding than those which were Unteased. This effect was not observed (P > 0.05) in CS 1.5 ewe lambs. In Study 3, a greater (P < 0.05) percentage of CS 2.5+ ewe lambs conceived over the 34-day breeding period than ewe lambs of lower CS. In Studies 2 and 3, ewe lambs with a CS of 2.5+ had a greater (P < 0.05) number of fetuses per ewe lamb presented for breeding than CS 1.5 ewe lambs. In conclusion, exposing ewe lambs to vasectomised rams in the late February or March period increased the proportion of ewe lambs successfully bred in the first 17 days of breeding. Further achieving higher CS and heavier liveweights of ewe lambs at breeding should result in improved reproductive performance.

Effect of nutrition pre-breeding and during pregnancy on breeding performance of ewe lambs

2010 ◽  
Vol 50 (10) ◽  
pp. 953 ◽  
Author(s):  
F. J. Mulvaney ◽  
S. T. Morris ◽  
P. R. Kenyon ◽  
P. C. H. Morel ◽  
D. M. West
Keyword(s):  
Pregnancy Rate ◽  
Breeding Period ◽  
Breeding Performance ◽  
Pregnancy Diagnosis ◽  
Breeding Group ◽  
Ewe Lambs ◽  
Ewe Lamb ◽  
Breeding Groups ◽  
Pregnant Ewe ◽  
Medium Group

The objective of the present studies was to investigate the effect of differing nutritional levels before breeding and during the pregnancy period on the breeding activity, conception rate (proportion pregnant/ewe lambs bred), pregnancy rate (proportion pregnant/ewe lambs joined with the ram) and the number of fetuses identified at pregnancy diagnosis. In Study 1, ewe lambs were allocated to either ‘medium’ or ‘ad lib’ levels of herbage from 4 days before the start of the breeding period (P –4) to P64. In Study 2, four different pre-breeding nutritional groups (‘maintenance’, ‘medium’, ‘medium/ad lib’ and ‘ad lib’) were utilised from P –17 until P5. The ‘medium/ad lib’ group involved a nutritional switch from the ‘medium’ to the ‘ad lib’ group at P –4 and remained in the ‘ad lib’ until P5. At P5, all ewe lambs that were identified as bred (crayon-marked by ram) were allocated to either ‘medium’ or ‘ad lib’ levels of nutrition until P122. In Study 1, more (P < 0.05) ewe lambs were bred, identified as pregnant at P64 and more fetuses identified at P64 in the ‘ad lib’ group compared with the ‘medium’ group. In Study 2, fewer (P < 0.05) ‘maintenance’ pre-breeding group ewe lambs were bred over the 5-day breeding period compared with the other pre-breeding groups but the proportion of the ewe lambs pregnant at P53 did not differ (P > 0.05). In addition, more (P < 0.05) fetuses were identified at pregnancy diagnosis in the ‘ad lib’ pre-breeding group compared with all other pre-breeding groups. Post-breeding nutrition did not affect (P > 0.05) the proportion of ewe lambs displaying oestrus post-breeding, pregnancy rate or the number of fetuses identified at pregnancy diagnosis per ewe lamb present. This indicates that New Zealand pastoral farmers should aim to allow ad libitum levels of nutrition immediately before the start of the breeding period to pregnancy diagnosis to maximise the number of fetuses at pregnancy diagnosis.

Does dam parity affect the performance of ewe progeny born to 2-year-old ewes?

2008 ◽  
Vol 48 (7) ◽  
pp. 979 ◽  
Author(s):  
P. R. Kenyon ◽  
S. T. Morris ◽  
H. T. Blair ◽  
K. J. Stafford
Keyword(s):  
Production Systems ◽  
First Year ◽  
Productive Performance ◽  
Breeding Performance ◽  
Female Progeny ◽  
Ewe Lambs ◽  
Birth Rank ◽  
Condition Score ◽  
Ewe Lamb ◽  
Puberty Onset

An increasing number of ewe lambs are being presented for breeding in New Zealand, resulting in more two-tooth ewes of second parity compared with the more normal first parity. The effect of this on the resulting ewe progeny is unknown but is of interest as they are potential replacement ewes. This study was designed to determine if parity of Romney two-tooth ewes had any effect on their ewe lamb progeny to 20 months of age. Two-hundred and fifty female progeny born to two-tooth dams, which had lambed as a ewe lamb (n = 97), failed to conceive at ewe lamb breeding (n = 79), or had not been presented for breeding as a ewe lamb (n = 74), were weighed at regular intervals. The progeny also had onset of puberty and two-tooth breeding and pregnancy scanning performance measured. There were no effects of dam group on liveweight, condition score, 18-month breeding performance or pregnancy diagnosis. However, ewe lambs born to dams which failed to conceive as ewe lambs themselves were less likely (P < 0.05) to achieve puberty. In comparison with single-born lambs, twin-born ewes were lighter (P < 0.05) during their first year of age only. Birth rank had no effect on puberty onset or 18-month breeding performance. These findings indicate that ewe progeny born to second parity two-tooths or two-tooths, which were not presented for breeding as a ewe lamb, do not differ in their productive performance and that either group are suitable as replacement ewes. However, progeny born to two-tooth dams, which failed to conceive as a ewe lamb, would be less suitable as replacement ewes in production systems where ewe lamb breeding is an integral component of the system. Further studies are required to determine if similar relationships would be observed under differing environmental conditions and with different breeds.

scholarly journals Effects of management system on beef heifer growth and reproductive performance

2020 ◽  
Author(s):  
Parker A Henley ◽  
Frank A Ireland ◽  
Igor F Canisso ◽  
J Lannett Edwards ◽  
Daniel W Shike
Keyword(s):  
Development Strategy ◽  
Breeding Season ◽  
Reproductive Performance ◽  
Body Condition Score ◽  
Pregnancy Rates ◽  
Fescue Toxicosis ◽  
Soybean Hulls ◽  
Randomized Design ◽  
Condition Score ◽  
Calf Performance

Abstract This study evaluated the effect of heifer development system on body weight (BW), body condition score (BCS), fescue toxicosis symptoms, reproductive performance, and subsequent calf growth of fall-calving beef heifers. Angus × Simmental heifers [n = 399; 240 ± 20.0 kg initial BW; age = 252 ± 20 d] were stratified by BW and BCS and assigned to 1 of 12 groups in each of the 2 production years. The study utilized a stratified randomized design. Pens were randomly assigned to 4 treatments: drylot (DL) development (fed ad-libitum diet consisting of 90% hay and 10% DDGS on a dry matter basis), grazing endophyte-infected fescue supplemented daily (2.3 kg as-fed/heifer/d; 50:50 mix of soybean hulls and DDGS; E+/S), grazing endophyte-infected fescue and supplemented from the midpoint of treatment period until breeding (4.5 kg as-fed/heifer/d; 50:50 mix of soybean hulls and DDGS; E+/LS), and grazing novel endophyte-infected fescue with no supplement (NE+/NS). Treatments ceased on d 168 [time of artificial insemination (AI)] and heifers were commingled and managed as a group through second breeding season. Heifers in DL had greatest (P ≤ 0.05) BW and BCS from d 28 until d 254. Furthermore, E+/S heifers had greater (P ≤ 0.05) BW and BCS than both E+/LS and NE+/NS from d 28 until d 168. On d 56 and 84, E+/LS heifers had lower (P ≤ 0.05) BW and BCS compared to NE+/NS, but on d 148 treatments reranked and E+/LS remained at a greater (P ≤ 0.05) BW and BCS compared to NE+/NS through the first breeding season. Drylot heifers had greatest (P ≤ 0.05) percentage cycling and percentage of mature BW at AI (66.6%) and had greater (P ≤ 0.05) AI and overall pregnancy rates compared to E+/LS and NE+/NS. The E+/S (55%) and E+/LS (53.7%) heifers were developed to a greater (P &lt; 0.01) percentage of mature BW than NE+/NS (49.3%). A greater (P ≤ 0.02) percentage of DL and E+/S heifers were pregnant at the end of the first breeding season (89.3 and 85.1%; respectively) compared to NE+/NS (61.5%). In summary, DL heifers had the greatest BW and BCS at AI, percentage cycling, and AI pregnancy rate. However, this strategy did not result in differing overall pregnancy rates between DL, E+/S, and E+/LS and there were no differences in milk production, rebreeding reproductive performance, and calf performance between all treatments. Finally, the poorest AI and overall pregnancy rates of the NE+/NS heifers suggests this is not a viable development strategy for fall-born heifers.

Single female offspring born to primiparous ewe-lambs are lighter than those born to adult multiparous ewes but their reproduction and milk production are unaffected

2012 ◽  
Vol 52 (7) ◽  
pp. 552 ◽  
Author(s):  
M. F. P. Loureiro ◽  
S. J. Pain ◽  
P. R. Kenyon ◽  
S. W. Peterson ◽  
H. T. Blair
Keyword(s):  
Milk Production ◽  
Reproductive Performance ◽  
Crude Protein ◽  
Female Offspring ◽  
Productive Performance ◽  
Single Female ◽  
Ewe Lambs ◽  
Ewe Lamb ◽  
Generation Offspring

Little is known about the long-term impacts of selecting progeny born to ewe-lambs (EL) as replacements. This study investigated whether being born to a ewe-lamb affected the liveweight, milk production and reproductive performance of the offspring to 3 years of age in comparison with those born to adult multiparous ewes. Twenty-seven and 28 single-born Romney ewe progeny (G1) were born to either EL or to adult ewes (AE), respectively. Offspring born to ewe-lambs (ELG1) were lighter (P < 0.001) at birth and up to 12 months of age compared with offspring born to adult ewes (AEG1). Reproductive performance of AEG1 and ELG1 did not differ in regards to puberty attainment, pregnancy rate and number of fetuses. First lactation milk production, fat, crude protein, total protein, casein, lactose and total solids yield did not differ (P > 0.05). The second generation offspring born to ELG1 and AEG1 did not differ in birthweight in the first parity, but it did differ in the second parity and those lambs born to ELG1 were heavier from birth to weaning compared with those lambs born to AEG1. Combined, these results indicate, in the animals used in our study that productive performance of ewes born to EL does not differ to 3 years of age to that of ewes born to AE.

Ewe lamb nutrition during pregnancy affects pregnancy outcome

2008 ◽  
Vol 48 (8) ◽  
pp. 1085 ◽  
Author(s):  
F. J. Mulvaney ◽  
P. R. Kenyon ◽  
S. T. Morris ◽  
D. M. West
Keyword(s):  
Treatment Group ◽  
Survival Rates ◽  
Breeding Period ◽  
Treatment Groups ◽  
Ewe Lambs ◽  
Ewe Lamb ◽  
Pregnant Ewe ◽  
High Level ◽  
The Impact ◽  
High Treatment

This experiment aimed to investigate the impact of pregnancy nutritional treatment on ewe lamb pregnancy rate and pregnancy loss and the liveweight of resulting lambs. Two hundred and forty ewe lambs mated during a 5-day breeding period were randomly allocated to one of three nutritional regimes (‘low’, ‘medium’ and ‘high’). The low (n = 80) treatment group was fed pasture to maintain liveweight during the first 100 days of pregnancy, thereafter feeding was increased to achieve a total liveweight change of 180 g/day. The medium treatment group was fed to ensure a liveweight change equivalent to 100 g/day throughout the entire pregnancy period, while the high treatment group was offered feed ab libitum. The target liveweight changes were achieved in all ewe lamb treatment groups. Fewer (P < 0.05) ewe lambs were scanned pregnant at day 50 of pregnancy and lambed in the high treatment compared with their medium counterparts. In addition, fewer (P < 0.05) low treatment ewe lambs lambed compared with the medium treatment ewe lambs. The lower numbers lambing in the low and high treatment groups were somewhat explained by greater (P < 0.05) pregnancy losses between day 50 and term. Lambs born to low treatment ewe lambs were lighter (P < 0.05) at birth (L0), L53 and L87 and had lower (P < 0.05) survival rates than those born to either medium or high treatment ewe lambs. While the present study was not designed to identify optimal ewe lamb feeding levels in pregnancy, it clearly indicates adverse effects from either a low or high level of pregnancy nutrition beginning in early pregnancy. Therefore, further studies are required to identify the optimal pastoral feeding conditions for the pregnant ewe lamb.

scholarly journals Abortion and Lamb Mortality between Pregnancy Scanning and Lamb Marking for Maiden Ewes in Southern Australia

Animals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 10
Author(s):  
Thomas Clune ◽  
Amy Lockwood ◽  
Serina Hancock ◽  
Andrew N. Thompson ◽  
Sue Beetson ◽  
...  
Keyword(s):  
Cohort Study ◽  
Reproductive Performance ◽  
Important Contributor ◽  
Ewe Lambs ◽  
Ewe Lamb ◽  
Overall Mortality

The contribution of abortions to the overall mortality of lambs born to maiden (primiparous) ewes in Australia remains unclear. This cohort study aimed to quantify abortion and lamb mortality for ewe lambs and maiden Merino two-tooth ewes. Lamb mortality from pregnancy scanning to marking were determined for 19 ewe lamb and 11 Merino two-tooth ewe flocks across southern Australia. Average lamb mortality from scanning to marking was 35.8% (range 14.3–71.1%) for the ewe lambs and 29.4% (range 19.7–52.7%) for the two-tooth ewes. Mid-pregnancy abortion was detected in 5.7% of ewes (range 0–50%) in the ewe lamb flocks and 0.9% of ewes (range 0–4.4%) in the two-tooth ewe flocks. Mid-pregnancy abortion affecting ≥2% of ewes was observed in 6/19 ewe lamb flocks and 2/11 two-tooth ewe flocks. Lamb mortality from birth to marking represented the greatest contributor to foetal and lamb mortality after scanning, but mid-pregnancy abortion was an important contributor to lamb mortality in some ewe lamb flocks. Variability between the flocks indicates scope to improve the overall reproductive performance for maiden ewes by reducing foetal and lamb losses. Addressing mid-pregnancy abortion may improve the reproductive performance in some flocks.

Reproductive performance of ewe lambs: genetic correlation with weaning weight and subsequent reproductive performance

1976 ◽  
Vol 16 (80) ◽  
pp. 321 ◽  
Author(s):  
R Barlow ◽  
CJ Hodges
Keyword(s):  
Genetic Correlation ◽  
Reproductive Performance ◽  
Agricultural Research ◽  
Reproductive Rate ◽  
Research Station ◽  
Weaning Weight ◽  
Net Reproductive Rate ◽  
Ewe Lambs ◽  
Ewe Lamb ◽  
Selection For

The reproductive performance of Merino ewe lambs was examined in flocks with different selection histories for growth to weaning and net reproductive rate. These ewes were drawn from selection flocks maintained at the Agricultural Research Station, Trangie. There was evidence of a positive genetic correlation between weaning weight and reproductive performance of ewe lambs. Selection for weaning weight had a significant effect on the percentage of ewes lambing (P < 0.05). This appeared to be a function of a higher level of fertility (P <0.05) and a higher proportion of ewes mating (n.s.). The proportion of ewes apparently in oestrus during a 39 day teasing period, prior to joining, was significantly influenced by selection for weaning weight (P < 0.05). Simultaneous selection for increased net reproductive rate, weaning weight and clean fleece weight did not result in higher ewe lamb performance than that achieved by selection for increased weaning weight alone. No conclusion could be drawn from these data about the correlation between net reproductive rate and reproductive performance of ewe lambs.

Effect of body condition and breeding history on the reproductive performance of twenty month old female breeding sheep

1993 ◽  
Vol 1993 ◽  
pp. 92-92
Author(s):  
Linda M Mitchell ◽  
Margaret E King
Keyword(s):  
Body Condition ◽  
Reproductive Performance ◽  
Body Condition Score ◽  
Combined Effect ◽  
Embryo Mortality ◽  
Optimum Performance ◽  
Ewe Lambs ◽  
Agricultural College ◽  
Condition Score ◽  
Breeding History

Ovulation rate in the ewe is positively related to body condition score (Gunn, Doney and Smith, 1979). For optimum performance it has been recommended that ewes should be in body condition score 3.5 at mating (MLC. 1981). However excessive fatness (body condition score 3.5 and above) has been associated with a reduction in lambing performance as a consequence of increased embryo mortality (Rhind, Gunn, Doney and Leslie. 1984).Previous studies at the Scottish Agricultural College-Aberdeen (King and Mitchell. 1990) have demonstrated superior reproductive performance for twenty month old female breeding sheep (gimmers) which have bred successfully as ewe lambs. The objective of the present study was to investigate the combined effect of body condition and breeding history (bred or unbred at eight months of age) on fecundity.

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