Skin folds 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

1965 ◽  
Vol 5 (18) ◽  
pp. 236 ◽  
Author(s):  
RB Dun ◽  
BA Hamilton
Keyword(s):  
Birth Weight ◽  
Genetic Correlation ◽  
Reproductive Performance ◽  
Maternal Effect ◽  
Reproductive Rate ◽  
Independent Data ◽  
Net Reproductive Rate ◽  
Skin Fold ◽  
Cent Mortality ◽  
The Difference

Reciprocal matings were carried out between the Trangie Folds Plus and Folds Minus selection Aocks in March 1961 and 1962. Folds Minus rams were more fertile than Folds Plus rams as shown by ewes lambing per insemination (72 per cent versus 48 per cent, P&0.01) and by incidence of twinning per ewe lambing (57 per cent versus 34 per cent, P<0.05). Folds Plus and Folds Minus ewes showed a similar reproductive performance if mated to the same rams. 236 There was a 17 per cent mortality in single lambs born to Folds Plus ewes compared with 4 per cent (P<0.05) for single lambs born to Folds Minus ewes. This increased mortality was caused by dystocia in association with relative oversize of the lamb. A positive genetic correlation of 0.32 � 0.21 between fold score and corrected birth weight was calculated using independent data. The mortality of twin lambs born to Folds Minus ewes was higher than for Folds Plus ewes (18 per cent versus 11 per cent). There was a maternal effect on the birth weight of twins, which were relatively much heavier from Folds Plus ewes. Approximately 80 per cent of the difference in net reproductive rate between the Folds Minus and Folds Plus flocks was explained on the basis of infertility of Folds Plus rams and excessively heavy birth weights of Folds Plus lambs.

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.

Skin folds and Merino breeding. 1. The net reproductive rates of flocks selected for and against skin fold

1964 ◽  
Vol 4 (15) ◽  
pp. 376 ◽  
Author(s):  
RB Dun
Keyword(s):  
Vital Statistics ◽  
Reproductive Rate ◽  
Relative Importance ◽  
Differential Survival ◽  
Net Reproductive Rate ◽  
Skin Fold ◽  
Single Character ◽  
Selection For ◽  
The Difference ◽  
Reproductive Rates

Single character selection flocks-Folds Plus (selection for high fold score) and Folds Minus (selection for low fold score)-were established at Trangie in 1951 from a Peppin Merino flock. The Trangie environment over the period 1951 to 1960 has been described relative to the management of these experimental flocks. An analysis of the vital statistics for the first nine joinings showed a net reproductive rate (the number of 19 month old replacement ewes produced by a ewe in her lifetime) for Folds Plus of 1.248 compared with 2.270 for Folds Minus. This resulted from the Folds Minus flock having a higher percentage of ewes wet and twins mothered, from it having lower mortality rates of young sheep between birth and mothering, between mothering and weaning, and between weaning and 19 months, as well as from it having lower death and casting rates of mature ewes. An analysis of the relative importance of each component of net reproductive rate (N) in contributing to the difference between the Folds flocks (percentage deviation technique) showed :- 1. Twenty eight per cent of the difference could be ascribed to wet ewes (W) and nine per cent to twinning (M) a total of 37 per cent from lambs born per ewe mated (L). 2. Differential survival rate of lambs between birth and 19 months (S) contributed 36 per cent, made up of 17 per cent birth to mothering (Sm), 11 per cent mothering to weaning (Sw), and 8 per cent weaning to 19 months (Sj). 3. The remaining 27 per cent was contributed by the annual wastage of breeding ewes as this affected the number of times a ewe is joined in her lifetime (J). This component was further divided into 16 per cent from death rate (D) and 11 per cent from casting rate (C).

Time of joining affects the performance of young Angus and Angus multiply Friesian cattle in the south-west of Western Australia. 1. Liveweight, body condition, and reproductive performance in heifers and first-calvers

1993 ◽  
Vol 33 (5) ◽  
pp. 511
Author(s):  
GJ Sawyer ◽  
J Milligan ◽  
DJ Barker
Keyword(s):  
Reproductive Performance ◽  
Post Partum ◽  
Reproductive Rate ◽  
Grazing Pressure ◽  
Net Reproductive Rate ◽  
South West ◽  
Significant Difference ◽  
Breeding Herd ◽  
Conception Date ◽  
Friesian Cattle

A 3-year study using 183 Angus and 173 Angus x Friesian first-calf heifers joined at about 15 months of age was conducted to determine the effects of time of calving and breed on liveweight and condition, heifer reproductive performance, oestrus activity after calving, and subsequent conception. Pasture on offer and supplements were also measured. Calving times used were April (conventional calving time), March (4 weeks earlier), and May (4 weeks later). There was no significant effect of time of calving on net reproductive rate in heifers of either breed, but the number of stillbirths and dystocias in later calved Angus were greater than in Angus x Friesian. Protracted and difficult calvings were more prevalent in heifers of both breeds calving early. Highest pregnancy rates of 93-94% corresponded with the highest average liveweights at conception in nulliparous heifers of both breeds that were mated to first-calve later. Angus x Friesian first-calvers consistently returned to oestrus before Angus after their first calving. In a year when grazing pressure on depleted dry pasture residues caused significant liveweight loss in both breeds, the crossbreds commenced cycling, on average, 20-32 days before the Angus. Regression of calving date and length of the post-partum anoestrous interval (PPAI) was -0.54 days/day for Angus and -0.3 1 days/day for Angus x Friesian. There was no significant difference between breeds for time to conception. The regression of second conception date on first calving date was 0.10 days/day in Angus and 0.17 days/day in Angus x Friesian. Heavier first-calvers of both breeds returned to oestrus earlier; each extra 10 kg in liveweight was associated with shorter PPAI by 3.9 days in Angus and 1.7 days in Angus x Friesian crossbreds. Heavier first-calvers of both breeds also conceived earlier; however, about twice as much weight was required to reduce the time to conception in the larger Angus x Friesian crossbreds than in the Angus. Times to first oestrus and to conception were negatively and linearly related to condition only in Angus first-calvers. Conception rates after first calving did not differ between time-of-calving groups or breeds in 2 years, but in a difficult year and if calved later, only 73% of Angus and 61 % of Angus x Friesians were pregnant after 90 days of joining. We conclude that there is little justification on the grounds of reproductive performance for varying the time of calving of heifers from that of the main breeding herd.

A crossbreeding experiment with cattle, with special reference to the maternal effect in South Devon—Dexter crosses

1958 ◽  
Vol 51 (3) ◽  
pp. 325-341 ◽  
Author(s):  
D. M. Joubert ◽  
John Hammond
Keyword(s):  
Birth Weight ◽  
Maternal Effect ◽  
Significant Degree ◽  
Maternal Influence ◽  
Stages Of Growth ◽  
Definite Effect ◽  
Significant Difference ◽  
Respective Parent ◽  
The Mean ◽  
The Difference

An investigation was carried out to determine the extent of the maternal influence on size of calves at birth and during subsequent stages of growth, by making reciprocal matings between large South Devon and small Dexter cattle. As a preliminary to the experimental results, data concerning the respective parent breeds were analysed. From the first part of the study the following information was obtained:1. The mean weight at birth of purebred South Devon calves was 100·3 ± 1·47 lb. with a tendency, though not statistically significant, for male calves to be heavier. Calves born during the months April to July appeared to be heavier than those born at other times, but the age of the dam had no definite effect on the birth weight of offspring. It was found, however, that the sire may influence birth weight to a significant degree.2. The mean period of pregnancy for South Devon females, carrying purebred foetuses, was 287·0 ± 0·42 days, the tendency being for males to be carried longer, but the difference of 0·97 days was not statistically significant. A statistically significant difference indicated that winter calvers carry their foetuses longer as a rule, but though heifers have shorter gestation periods than cows, the difference of 1·6 days was not significant.

scholarly journals Comparative demography of the exotic Harmonia axyridis with other aphidophagous coccinellids reared on artificial diet

2014 ◽  
Vol 49 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Julianne Milléo ◽  
Francisco Sales Fernandes ◽  
Wesley Augusto Conde Godoy
Keyword(s):  
Life Table ◽  
Harmonia Axyridis ◽  
Reproductive Rate ◽  
The Other ◽  
Adult Longevity ◽  
Net Reproductive Rate ◽  
Anagasta Kuehniella ◽  
Survival Percentage ◽  
Comparative Demography ◽  
Biological Aspects

The objective of this work was to compare biological aspects and life table parameters of the coccinellids Harmonia axyridis, Cycloneda sanguineaand Hippodamia convergens. Insects were fed eggs of Anagasta kuehniella, and reared at 24.5±1ºC, 70±10% relative humidity, with a 12 hour photophase. Hippodamia convergenstook about 1.6 day to complete development, longer than H. axyridis, and 2.4 day longer than C. sanguinea.At immature stages, H. axyridisexhibited the highest survival percentage (49.2%), in comparison to the other coccinellids. For mean adult longevity, H. convergenswas deficient, in comparison with the other species. Mean period of pre oviposition was the longest in C. sanguinea; the longest oviposition time occurred for H. axyridis; and the post oviposition period was similar between the coccinellids. Considering the reproductive parameters, H. axyridisshowed the best performance in all aspects. For life table, the values of H. convergenswere higher than, although close, to those of H. axyridis. Nevertheless, the high net reproductive rate of H. axyridis showed this species potential to increase population size. The biological characteristics of the exotic H. axyridis favors its invasion and establishment in Brazil, corroborating results noticed in other countries.

scholarly journals 88 Benefits of increasing amino acid intake in late gestation in prolific sows

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 76-76
Author(s):  
Ron Ball ◽  
Crystal L Levesque ◽  
D J Cadogan
Keyword(s):  
Birth Weight ◽  
Amino Acid ◽  
Reproductive Performance ◽  
Essential Amino Acid ◽  
Control Diet ◽  
Genetic Selection ◽  
Late Gestation ◽  
Negative Effects ◽  
Amino Acid Levels ◽  
The Many

Abstract Most sows are fed a constant energy and amino acid supply throughout gestation, in line with the recommendations of most authorities and swine genetic companies. These recommendations for sow feeding have seen little change in decades, despite the many ways that sows have changed dramatically in reproductive performance. Beginning in about the year 2000, sow litter size has steadily increased as a result of genetic selection. With this increase in litter number has been a steady decline in birth weight, and the resulting negative effects of lower birthweight on subsequent piglet performance. Many experiments using so-called ‘bump’ feeding, or increased energy intake in late gestation, have been conducted in attempts to arrest this decline in birthweight and piglet performance. Generally, these experiments have shown little to no improvement in birthweight and often have negative effects on sow feed intake during gestation. These experiments have ignored the fact that the energy:amino acid ratios (lysine, threonine, isoleucine, tryptophan) in late gestation are different than during early and mid-gestation. In recent research in Australia we hypothesised that rapidly increasing essential amino acid levels in late gestation would increase birth weight and potentially improve subsequent reproductive performance. Three hundred and thirty-four multiparous PIC sows (average parity 3.6, average LW 261 kg) were housed in a dynamic gestation pen after mating and randomly assigned to one of two diet regimes. Two 13.5 MJ/kg DE gestation diets were formulated and created by blending in an ESF. The Control diet contained 0.48 g SID lysine per MJ DE and SID threonine, methionine+ cysteine, isoleucine and tryptophan at 68%, 65%, 58% and18% of SID lysine and offered at 2.2kg/day from d 28 to d 110. Sow were then moved to the farrowing house and placed on a lactation diet at 3.5kg/d. The Treatment diet contained 0.55 g SID lysine/MJ DE and SID threonine, methionine+cysteine, isoleucine and tryptophan at 78%, 65%, 60% and 20% of SID lysine and offered at 2.1kg/d from d 28 to d 85 and then increased to 2.4 kg/d to d 110 d. Increasing essential amino acid levels in late gestation increased gestational weight gain (5.6 kg, P=0.004), increased total litter birth weight (1.25 kg, P=0.003), and increased the birthweight of liveborn pigs from 1.286 to 1.329 kg, (P=0.04). There was no significant effect on the total number born or born alive. Piglet performance is not available because this commercial farm practices cross-fostering. Effects of continuation of this feeding regime in the same sows during subsequent parities is currently being evaluated.

scholarly journals Effects of Delayed Mating on the Reproductive Performance of Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae)

Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 629
Author(s):  
Ya-Ling Wang ◽  
Qi-Nian Jin ◽  
Xiang-Ping Wang
Keyword(s):  
Life Table ◽  
Mating Success ◽  
Doubling Time ◽  
Reproductive Rate ◽  
Oviposition Period ◽  
Population Doubling ◽  
Life Table Parameters ◽  
Effective Measure ◽  
Net Reproductive Rate ◽  
Henosepilachna Vigintioctopunctata

Henosepilachna vigintioctopunctata (F.) is a serious pest of numerous solanaceous crops in many Asian countries. The purpose of this study was to clarify the effects of delayed mating on mating success, fecundity, fertility, pre-oviposition period, oviposition period, adult longevity, and population life table parameters (including net reproductive rate, intrinsic and finite rates of increase, doubling time, and mean generation time) of H. vigintioctopunctata. Beginning three days after emergence for both sexes, mating was delayed an additional 0, 2, 4, 6, or 8 days. We compared the data when mating was delayed for males only with the data when mating was similarly delayed for females only. Reproductive and life table parameters were calculated from the two data sets and compared. The results showed that the preoviposition and oviposition period of adults was significantly reduced by delayed mating, while the preoviposition period was not significantly different in adults mated at older ages. The mating success rate, fecundity, and proportion of hatching eggs decreased with increasing mating age. Longevity was not affected by the age at mating. Mating delay also affected the life table parameters of H. vigintioctopunctata, with a similar trend observed in the net reproductive rate and intrinsic and finite rates of increase, all of which decreased gradually as the number of delay days increased. The population doubling time increased with increases in mating age. The results also showed that delayed mating was an effective measure to consider in controlling H. vigintioctopunctata. It is hoped that our data will provide a scientific basis and contribute technical guidance for forecasting and integrated management of this pest.

Plant Resistance in Some Modern Soybean Varieties May Favor Population Growth and Modify the Stylet Penetration of Bemisia tabaci (Hemiptera: Aleyrodidae)

2021 ◽  
Author(s):  
Mauricélia F Almeida ◽  
Clébson S Tavares ◽  
Euires O Araújo ◽  
Marcelo C Picanço ◽  
Eugênio E Oliveira ◽  
...  
Keyword(s):  
Population Growth ◽  
Bemisia Tabaci ◽  
Intrinsic Rate ◽  
Reproductive Rate ◽  
Genetically Engineered ◽  
Population Increase ◽  
Net Reproductive Rate ◽  
Bt Toxin ◽  
Demographic Performance

Abstract Complaints of severe damage by whiteflies in soybean fields containing genetically engineered (GE) varieties led us to investigate the role of transgenic soybean varieties expressing resistance to some insects (Cry1Ac Bt toxin) and to herbicide (glyphosate) on the population growth and feeding behavior of Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae). In the laboratory, the whiteflies reared on the GE Bt soybeans had a net reproductive rate (R0) 100% higher and intrinsic rate of population increase (rm) 15% higher than those reared on non-GE soybeans. The increased demographic performance was associated with a higher lifetime fecundity. In electrical penetration graphs, the whiteflies reared on the GE soybeans had fewer probes and spent 50% less time before reaching the phloem phase from the beginning of the first successful probe, indicating a higher risk of transmission of whitefly-borne viruses. Data from Neotropical fields showed a higher population density of B. tabaci on two soybean varieties expressing glyphosate resistance and Cry1Ac Bt toxin. These results indicate that some GE soybean varieties expressing insect and herbicide resistances can be more susceptible to whiteflies than non-GE ones or those only expressing herbicide resistance. Most likely, these differences are related to varietal features that increase host-plant susceptibility to whiteflies. Appropriate pest management may be needed to deal with whiteflies in soybean fields, especially in warm regions, and breeders may want to consider the issue when developing new soybean varieties.

scholarly journals Biological performance of the predatory mite Neoseiulus idaeus (Phytoseiidae): a candidate for the control of tetranychid mites in Brazilian soybean crops

2016 ◽  
Vol 77 (2) ◽  
pp. 361-366 ◽  
Author(s):  
M. B. Reichert ◽  
M. Toldi ◽  
P. A. Rode ◽  
J. J. Ferla ◽  
N. J. Ferla
Keyword(s):  
Adult Development ◽  
Predatory Mite ◽  
Reproductive Rate ◽  
Agricultural Crop ◽  
Net Reproductive Rate ◽  
Glycine Max L ◽  
The Mean ◽  
Neoseiulus Idaeus ◽  
Biological Performance ◽  
Northwest Region

Abstract The soybean (Glycine max (L.): Fabaceae) is considered the most important agricultural crop in Brazil. Phytophagous tetranychid mites as Mononychellus planki McGregor, Tetranychus ludeni Zacher and T. urticae Koch have been considered pest in soybean crops. Neoseiulus idaeus Denmark & Muma (Phytoseiidae) is a predatory mite of T. ludeni and T. urticae. The aim of the present study was to evaluate the biological performance of N. idaeus when fed on T. urticae, T. ludeni and M. planki, coming from the Northwest region of Rio Grande do Sul state, Brazil. The study was conducted in the laboratory with individual predators supplied with different preys. The mean duration (days) of N. idaeus egg-adult development was similar independently of supplied prey (T. ludeni - 5.29±0.03; M. planki - 5.34±0.05 and T. urticae - 5.23±0.03 days). Female viability was 90% when fed on M. planki and 100% when fed on T. ludeni and T. urticae. Mean fecundity of N. idaeus was lower when fed on M. planki (4.6±1.58 eggs/female) and higher when fed on T. ludeni (21.8±3.22) and T. urticae (26.2±2.41). The mean generation time (T) was lower when N. idaeus fed on M. planki than when fed on T. ludeni and T. urticae. The net reproductive rate (Ro) was 4.42±0.49 on M. planki, 17.77±0.55 on T. ludeni and 20.59±0.48 on T. urticae. The innate capacity for increase (rm) was lower when N. idaeus was fed on M. planki (0.09) and higher when such predator was fed on T. ludeni (0.20) and T. urticae (0.22 females/females/day). These results demonstrated that N. idaeus is able to reach the complete development feeding on all the three tetranychid species. Mononychellus planki demonstrated to provide a sub-optimal diet if compared to T. ludeni and T. urticae.

128 Differences in PRRSV Resilience for Reproductive Performance Between Landrace and Duroc Sows

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 18-19
Author(s):  
Felipe Hickmann ◽  
José Braccini Neto ◽  
Luke M Kramer ◽  
Kent A Gray ◽  
Yijian Huang ◽  
...  
Keyword(s):  
Reproductive Performance ◽  
Mixed Model ◽  
Performance Data ◽  
The Other ◽  
Wild Type ◽  
Prrs Virus ◽  
The Difference ◽  
The Impact

Abstract Studies on differences in resilience to porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) between breeds are scarce in the literature. Thus, the objective of this work was to assess PRRSV resilience in PRRSV wild-type infected sows from two breeds. Farrowing data included 2546 and 2522 litters from 894 Duroc and 813 Landrace sows, respectively, which were housed together and experienced the same PRRSV outbreak. Traits used for this study were number of piglets born alive (NBA), number born dead (NBD), total number born (TNB), and number weaned (NW). The impact of PRRSV infection was evaluated by comparing the reproductive performance of breeds between PRRS phases (pre-PRRS, PRRS, and post-PRRS). PRRS phases were defined based on the reproductive performance data. NBA, NBD, and NW were analyzed as a proportion of TNB using a Poisson mixed model. Pre-defined contrasts were used to evaluate the effect of breed on PRRSV resilience and on return to PRRSV-free performance, representing the differences between breeds for the difference between pre-PRRS and PRRS phases, and pre-PRRS and post-PRRS phases, respectively. There was a significant (P ≤ 0.003) interaction between PRRS phase and breed for all traits, as shown in Table 1. In general, reproductive performance reduced from pre-PRRS to PRRS, and then increased from PRRS to post-PRRS, as expected. The resilience contrast was significant for all traits (P ≤ 0.003). In all cases, the drop in percent reproductive performance from pre-PRRS to PRRS was lower for Duroc than for Landrace, indicating that Duroc sows have greater PRRSV resilience than Landrace sows. The return to PRRSV-free performance contrast had a trending effect for NBD (P = 0.055), and it was not significant for the other traits (P ≥ 0.515). These results indicate that Duroc sows have overall greater phenotypic PRRSV resilience for reproductive performance than Landrace sows.

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