Crossbred sheep production I. Factors affecting production from the crossbred ewe flock

1964 ◽  
Vol 6 (1) ◽  
pp. 73-84 ◽  
Author(s):  
B. C. Yalçin ◽  
Maurice Bichard
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Selective Breeding ◽  
Live Weight ◽  
Correction Factors ◽  
Secondary Product ◽  
Factors Affecting ◽  
Fleece Weight ◽  
Sheep Production

Donald (1962) has recently pointed out the paucity of available data on production from British sheep, though some information is available for hill sheep (see for example Donald, 1958; Purser and Roberts, 1959; Purser and Young, 1959; Dalton, 1962). Most of these refer mainly to the Scottish Blackface and Welsh Mountain breeds. Hill sheep form approximately 40% of the national flock of over 11 million breeding ewes. Another 40% of ewes are found in crossbred flocks mainly kept on the lowlands; these produce fat lambs and hoggets with wool as a secondary product. Very little information has so far been published on these crossbred ewes, exceptions being work reported by Bywater (1945) and Rennie (1957). This is the first of three papers to be presented with the object of providing such information, and is based mainly on the work of Yalçin (1963). It is hoped that these papers will be of use on two counts:1. To provide a documentation of one specific cross, the Border Leicester × Cheviot ewe and her Suffolk-cross lambs under North of England grassland conditions.2. To analyse the usefulness of keeping production records within such flocks as aids to good commercial management, to culling and to selective breeding.In this paper the traits studied are body weight, fleece weight and litter size of the ewes, and the weights of the lambs between birth and slaughter or weaning. Estimates were obtained for the effects upon some of these traits of age and live-weight of ewe, and of sex, year and type of birth and rearing of the lambs. The usefulness of such correction factors is considered within recording schemes. In subsequent papers the effects on production of differences between crossbred ewes and between the rams used as fat lamb sires will be considered.

Some consequences of high flock prolificacy in an intensive grassland sheep production system

1975 ◽  
Vol 20 (2) ◽  
pp. 219-232 ◽  
Author(s):  
T. G. Boaz ◽  
W. M. Tempest
Keyword(s):  
Perinatal Mortality ◽  
Breeding Season ◽  
Litter Size ◽  
Growth Rates ◽  
Production System ◽  
Late Pregnancy ◽  
Optimal Level ◽  
Fleece Weight ◽  
Sheep Production ◽  
Lamb Growth

SummaryAn intensive sheep production system using flocks of 100 Scottish Halfbred (SHB), 100 Welsh Speckleface (WSF) and 100 Finn Blackface (FBF) ewes maintained by 8, 4 and 6 ha grassland respectively for a 5-year period, was investigated to establish the consequences of high flock prolificacy and the measures taken to achieve it, including PMS administration. Mating occurred in late October/November at ewe: ram ratios of 25 or 33: 1. Ewes were housed in winter and fed silage, with supplementary cereals in late pregnancy. Lambs in excess of 2 (SHB) and 1 (WSF and FBF) per ewe were artificially reared and fattened indoors; ewes and lambs at grass were rotationally grazed (with forward creep grazing by the lambs). Prolificacy in the SHB breed was 225 lambs born per 100 ewes mated for untreated ewes and 237 for hormone-treated ewes; 119 and 155 respectively for WSF ewes; and 255 for FBF ewes (all untreated). Lambs sold per 100 ewes mated were: for SHB, 200 and 177; WSF, 102 and 107; FBF, 201.Good ewe condition and heavy live weights at mating were associated with appetite problems on silage in late pregnancy; PMS injection with a failure to secure conception rates above 80% at the critical oestrus and a markedly lower prolificacy for ewes conceiving at later oestruses; mating in the middle of the breeding season and March/April lambing with slow lamb growth rates on grass in July and August. Hormone-induced high prolificacy was associated with a greater proportion of large multiple litters than natural high prolificacy, and consequent smaller lamb birth weights and more perinatal mortality. There was a significant negative regression relating fleece weight with litter size. The results suggest the existence of an optimal level of prolificacy for the system employed.

Gestation period, litter size and birth weight in the goat

1983 ◽  
Vol 36 (1) ◽  
pp. 105-110 ◽  
Author(s):  
E. A. Amoah ◽  
M. J. Bryant
Keyword(s):  
Birth Weight ◽  
Litter Size ◽  
Live Weight ◽  
Regression Equation ◽  
Gestation Period ◽  
General Linear ◽  
Factors Affecting ◽  
Interactive Model

ABSTRACTData from 265 female goats (does) from seven herds in Year 1 and 130 does from four herds in Year 2 were analysed using a general linear interactive model for factors affecting gestation period (GP), litter size (LS) and birth weight (BW) of offspring (kids). Gestation period could be described by the regression equation GP = α – 0·890LS –1·072S where S is the proportion of male kids in the litter and the constant (a) depends on breed and herd and was 154·240 (s.e., 0·843) days for British Saanen does in Herd 1. The model established for LS was a quadratic regressional relationship LS = a – 0·000103 (MW - 60))2 + 0-0172 (MW -60) where MW was live weight of the doe at mating and a at MW = 60 kg depends on herd and period of kidding. For early-kidding does in Herd 1 a was 2·277 (s.e., 0·090) kids. The expression BW —α 0·363LS + 0·057P is a simplified multiple regressional form involving BW, LS and parity (P) where a varies according to breed, herd and age of the doe. The estimate of a for kids from British Saanen, 1-year-old does in Herd 1 was 3·879 (s.e., 0·632) kg.

Repeatability and heritability of fertility in hill sheep

1965 ◽  
Vol 7 (1) ◽  
pp. 75-82 ◽  
Author(s):  
A. F. Purser
Keyword(s):  
Litter Size ◽  
Genetic Correlations ◽  
Live Weight ◽  
Heritability Analysis ◽  
Fleece Weight ◽  
Size At Birth

SUMMARYLambing records of 3,500 Scottish Blackface ewes and 2,000 Welsh Mountain ewes were used for a study of repeatability of ewe fertility and litter size. The repeatability of litter size at birth (calculated as an intra-ewe correlation) was higher in both flocks (0.19 and 0.24 for Blackface and Welsh ewes respectively) than that for barrenness (0.09 and 0.08) or for number of lambs born per mating (0.07 and 0.10). Repeatability of the corresponding traits at weaning were generally about half these values.About two-thirds of the ewes had sires recorded and were used for a heritability analysis. The heritability of litter size at birth in both flocks was higher (0.14 and 0.16 for Blackface and Welsh respectively) than either the heritability of barrenness (−0.03 and 0.03) or of numbers of lambs born per mating (−0.01 and 0.07).It was concluded that the greatest improvement in numbers of lambs weaned would be obtained by selection on litter size at birth. There would be correlated changes in live-weight (genetic correlations of 0.44 and 0.78 for Blackface and Welsh respectively) but not in fleece weight (genetic correlations of 0.09 and −0.13).

scholarly journals Factors affecting gestation length in small sized breeds of dogs.

2021 ◽  
Vol 52 (4) ◽  
Author(s):  
Vinaykumar R. H. ◽  
Gleeja V. L. ◽  
Gleeja V. L. ◽  
Gleeja V. L. ◽  
Gleeja V. L. ◽  
...  
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Gestation Length ◽  
Age Group ◽  
Gestational Length ◽  
Factors Affecting ◽  
Significant Difference ◽  
The Mean ◽  
Age Limit ◽  
French Bulldog

A large variation in the gestation length can be expected when the gestation is calculated from the day of mating to birth. The present study was designed to assess the influence of different factors like litter size, breed, parity and age on gestation length in bitches. A total of 89 small sized bitches of different breeds having different age, parity and body weight, were selected for the study. The mean age, body weight and parity of the animals included in the present study were 3.00 ± 0.15 years (1 to 8 years), 9.9 ± 0.25 Kg (6 to 15kg) and 1.14 ± 0.10 (0-4th parity) respectively. The mean gestation lengths observed in different small sized breeds were 60.68 ± 0.55, 59.82 ± 0.54, 60.78 ± 1.74, 58.83 ± 1.35 and 58.17 ± 0.74 in the Pug, Beagle, Dachshund, French Bulldog and the Spitz, respectively. The mean litter size in the study was 4.34 ± 0.13 with a range of 2-8. The mean gestational length in animals having ? 3 litter size was 60.83 ± 0.64 days and 59.90 ± 0.43 days in animals having >3 litter size. Age limit of the animals ranged from 1 to 8 years with a mean of 3 ± 0.15 years. The mean gestation length in bitches aged ?3 years was 60.21 ± 0.23 days (n=63) and this was 60.15 ± 0.3 (n=26) days in bitches in the >3 years group. Mean gestational length observed in nulliparous bitches was 60.86 ± 0.4 days (n=29), while in multiparous bitches it was 59.90 ± 0.5 days (n=60). From the present investigation it could be concluded that no significant difference exists in gestational length between different breeds, litter size, age group and parity.

FACTORS AFFECTING GESTATION LENGTH IN THE PIG

1979 ◽  
Vol 59 (1) ◽  
pp. 83-87 ◽  
Author(s):  
I. GARNETT ◽  
G. W. RAHNEFELD
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Weight Change ◽  
Average Daily Gain ◽  
Weight Ratio ◽  
Gestation Length ◽  
Small Litter ◽  
Factors Affecting ◽  
Number Of Factors ◽  
Breeding Groups

The effects of a number of factors on gestation length were examined in two groups of swine. The first group consisted of a Lacombe line (L) selected for post-weaning average daily gain (ADG), a control-Yorkshire (Y) line and a group of Yorkshire females (Y1) bred to Lacombe boars to produce L × Y litters. The second group of females were from twice-yearly farrowings following termination of the selection study. The effect of litter size, although statistically significant for all breeding groups, was small. Litter weight had a small but significant effect for the L and Y breeds. Sex ratio of the litter had no effect on gestation length. Consistent with previous results, the Lacombe was found to have a longer gestation length than the Yorkshire. When age effect was taken into account there was a small but significant parity effect between first and second litter. The effect of sow body weight at breeding (BW), body weight change during gestation (GWG), and weight change expressed as a proportion of breeding weight (RATIO) were examined in the group II females. A small but significant effect of RATIO was found in the Lacombe breed. There was found to be no sex effect on litter size. Heritability estimates for gestation length from daughter dam regression were 0.47, 0.72 and 0.69 for the L, Y and Y1 groups, respectively.

A genetic analysis of the components of lifetime productivity in Scottish Blackface sheep

1986 ◽  
Vol 43 (3) ◽  
pp. 405-419 ◽  
Author(s):  
K. D. Atkins
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Genetic Correlations ◽  
Direct Selection ◽  
Data Set ◽  
Body Weights ◽  
High Heritability ◽  
Adult Body Weight ◽  
Fleece Weight ◽  
Measures Of Performance

ABSTRACTReproductive performance, body growth, wool production and ewe survival were examined in Scottish Blackface sheep. The data set was from a large randomly selected population maintained under hill conditions between 1954 and 1974. Paternal half-sib analyses of variance were used to estimate heritabilities and genetic correlations, while maternal half-sib analyses of variance indicated the relative importance of maternal effects (both genetic and environmental).Among reproductive components, the heritability of fertility (ewes lambing per ewe mated) and lamb survival (lambs weaned per lamb born) were about zero. Litter size (lambs born per ewe lambing) had an estimated heritability of 0·12 (s.e. 0·04) and a repeatability of 0·22 (s.e. 0·02), indicating some scope for improvement. Additionally, the strong genetic correlation between adult body weight and litter size (0·66, s.e. 0·18) suggested greater response from a combination of indirect selection (on body weight) and direct selection (on dam's litter size). Prior to weaning, direct genetic effects on body weight were very small (heritability less than 0·1) with a large influence of maternal environment. After weaning, these maternal influences gradually diminished and the heritability of weight increased. Genetic correlations between body weights showed a similar increasing trend with age. Genetic improvement of early growth rate would be more effective by selecting on a post-weaning rather than a pre-weaning body weight. Fleece weight had a high heritability (about 0·5) but was genetically uncorrelated with other measures of performance. Ewe survival had a small genetic component although estimates of heritability were very imprecise.

scholarly journals Factors Affecting Birth Weight And Growth Rate In Friesian X Bunaji Calves

2021 ◽  
Vol 19 ◽  
pp. 101-106
Author(s):  
O. W. Ehoche ◽  
A. E. O. Malau-aduli ◽  
B. Y. Abubakar
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Birth Weight ◽  
Significant Influence ◽  
Season Of Birth ◽  
Correction Factors ◽  
Wet Season ◽  
Factors Affecting ◽  
Body Weights ◽  
The Mean

Calving records from 1984 - 1989 were studied to determine the influence of rearing method, sex of calf, season of birth, dam breed and year of birth on body weight at birth, 3,6 and 12 months of age in Friesian x Bunaji calves. The mean weights of calves at birth, 3, 6 and 12 months of age were 22.0, 68.2, 96.7 and 137.4 kg, respectively. Sex of calf had a significant effect, with male calves being heavier than the females by 1.2, 5.9 and 9.7 kg at birth, 3 and 6 months of age respectively. The effect of season of birth on calf body weights was not significant except at 6 months of age, when calves born during the wet season were heavier (P<0.01) than those born in the harmattan period by 9.5 kg. Year of birth had a highly significant effect (P<0.01) on calf weights from birth to yearling. Method of rearing and dam breed had no significant influence on all the weights. The results suggest the need to develop correction factors for standardisation of weight records when comparing dams on the basis of body weights of their calves.

Reproductive traits of female rabbits as affected by heat stress and lighting regime under subtropical conditions of Egypt

2004 ◽  
Vol 78 (1) ◽  
pp. 119-127 ◽  
Author(s):  
I. F. M. Marai ◽  
A. A. M Habeeb ◽  
A. E. Gad
Keyword(s):  
Body Weight ◽  
Heat Stress ◽  
Weight Gain ◽  
Respiration Rate ◽  
Litter Size ◽  
Milk Yield ◽  
Live Weight ◽  
Milk Intake ◽  
Live Weight Gain ◽  
Litter Weight

AbstractThe present work was planned to study the effects of different lighting regimes in both mild and hot periods of the year on New Zealand White doe rabbit traits. The light regimes used were natural daylight as control, 16 h light and 8 h darkness, 12 h light and 12 h darkness, and 8 h light and 16 h darkness. The traits studied were thermoregulatory parameters (respiration rate and temperatures of ear, rectum and skin), type of mating necessary, conception rate, gestation period, fur plucking, behavioural indicators of stress, litter size, litter weight, kit body weight, kit daily gain in weight, milk yield, kit milk intake, efficiency of conversion of milk into live-weight gain and kit mortality, at weekly intervals between birth and weaning at 35 days. Estimation of temperature-humidity index indicated that the doe rabbits were exposed to very severe heat stress, during the hot period of the year. Period of the year (heat stress) affected adversely many of the doe traits studied. The effects were significant (P < 0·001, 0·01 or 0·05) on thermoregulatory parameters (respiration rate and temperatures of ear, rectum and skin), litter weight at days 21 and 28 of age, kit body weight at birth, milk yield of the doe at day 7 of suckling and milk intake per kit at 7 and 14 days of age. Exposure of doe rabbits to a long daylight regime affected adversely many of the traits studied, while the contrary occurred with short daylight. The effects were significant (P < 0·001, 0·01 or 0·05) on litter size at all ages except at birth, litter weight at 14, 21 and 28 days of age, milk yield on all days studied, efficiency of conversion of milk into live-weight gain at days 7, 21 and 28 and mortality at birth and pre-weaning. There was no significant interaction between period of the year and light regime on any of the traits examined. Therefore, only the main factors are reported.

scholarly journals The Use of Regressions to Increase Heritability

1954 ◽  
Vol 7 (3) ◽  
pp. 363 ◽  
Author(s):  
JM Rendel
Keyword(s):  
Body Weight ◽  
Environmental Change ◽  
General Formula ◽  
Genetic Variance ◽  
Selective Breeding ◽  
Correction Factors ◽  
Breeding Work ◽  
Selection Indices ◽  
Tibia Length ◽  
Made In

The difficulties of applying correction factors to eliminate non-genetic variance in selective breeding work are discussed. The use of a second character as an index of environmental change is explored and related to the general formula for selection indices. Tibia length and body weight in mice are used to demonstrate points made in the theoretical discussions of the first part of the paper.

scholarly journals 237 Evaluation of fleece and fiber characteristics of ultrafine Paco-Vicunas farmed in Missouri

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 172-172
Author(s):  
Tumen Wuliji ◽  
Gloria Smith ◽  
Don Smith
Keyword(s):  
Birth Weight ◽  
Selective Breeding ◽  
Fiber Diameter ◽  
Live Weight ◽  
Herd Size ◽  
Average Fiber Diameter ◽  
Weaning Weight ◽  
Selective Mating ◽  
Fleece Weight ◽  
Mixed Age

Abstract Data recordings of animal breeding, fleece production, and fiber characteristics in an ultrafine Paco-Vicuna herd farmed at Victory Farm, Missouri were analyzed. A selective mating strategy was applied while establishing an ultrafine fleece growing Paco-Vicuna herd on the ranch over 12 years. The herd size was expanded from five males and one dozen breeding females in 2009 to more than 200 heads in 2016. All animals were recorded for sires, dams, and registered pedigree, birth weight, weaning weight, shearing weight, and fleece weight. Mid-side flank fleece samples were measured for Optical Fiber Diameter Analyser (OFDA) fiber characteristics, including mean fiber diameter, length, and fiber curvature. Live weight, fleece weight, and fiber characteristics were analyzed using SAS® GLM procedures. Mean birth weight, weaning weight, mixed age shearing weight, fleece weight, fiber diameter, coefficient of fiber diameter variation, fiber length, and fiber curvature were 6.82 kg, 25.27 kg, 48.84 kg, 0.85 kg, 16.6 µm, 25.2%, 64.6 mm and 56.9 degree /mm, respectively. The average fiber diameter of herd was 18.3 µm at 2009 clip, which was gradually but significantly (P &lt; 0.05) reduced yearly to 16.4 µm at 2019 clip. In addition, the finest 25 percent of the herd’s fleeces were tested and found to have an average fiber diameter of 14 micron, which was within vicuna fleece fiber diameter ranges. These measures did not significantly increase with ages. Heritability estimates for the fleece weight and fiber diameter, length, and curvature were 0.40, 0.65, 0.29, and 0.50, respectively. The average fiber diameter measurements of Paco-Vicuna herd at Victory Farm were significantly (P &lt; 0.01) finer than the comparable camelid herds in the country. This study found that strict selective breeding is effective for genetic gains in ultrafine fiber diameter and fleece quality in Paco-Vicunas.

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