Production benefits of the crossbreeding of indigenous and non-indigenous ducks—growing and laying period body weight and production performance

To evaluate different crosses and purebreds ducks in respect to various economic traits and to estimate different crossbreeding genetic parameters, a 3?×?3 complete diallel cross involving indigenous duck (DD), Khaki Campbell (KK) and White Pekin (WW) were used to produce three purebreds (DD, KK, WW) three crossbreds (DK, DW, KW) and three reciprocals (KD, WD, WK). A total of 609 ducklings produced were reared on deep litter and the females (316 in number) were evaluated for growing and laying period body weight along with the production performance traits. Different crossbreeding genetic parameters were estimated for different traits. All the traits in respect to body weight gain during growing and laying period and different production traits including laying house mortality rate showed significant (p?≤?0.05) difference between different genetic groups. In general, crossbreds perform better than the purebreds for most of the traits studied. General combining ability (GCA), specific combining ability (SCA) and reciprocal effect (RE) were significant (p?≤?0.01) for body weight and production traits. Egg weight showed significant (p?≤?0.01) difference in respect to GCA, SCA and RE for all the ages of measurement except RE for 30th week egg weight. Laying period mortality rate was only significant (p?≤?0.05) for SCA. Most of the crossbreds recorded heterosis rate in desirable direction for majority of the traits. Overall results revealed that the crossbreds perform well in respect to different traits than the purebreds and may be used to take advantage of heterosis. DW performs well in respect to majority of the traits measured and is of importance for commercial exploitation. Further, pure line selection with development of specialised sire and dam line followed by crossing may be of importance to enhance the performances in the crosses.     

Effect of Hoodia gordonii meal supplementation at finisher stage on productivity and carcass characteristics of Ross 308 broiler chickens

Two experiments were conducted to evaluate the effect of Hoodia gordonii meal supplementation at finisher stage on productivity and carcass characteristics of Ross 308 broiler chickens. The first experiment examined the effect of level of Hoodia gordonii meal supplementation at finisher stage (30 to 42 days of age) on productivity and carcass characteristics of chickens. Level of Hoodia gordonii meal supplementation had no effect (P > 0.05) on diet intake, growth rate, feed conversion ratio and live weight of chickens. Daily supplementation with 300 mg of Hoodia gordonii meal reduced (P < 0.05) fat pad weights by 40 % in broiler chickens The second experiment examined the effect of Hoodia gordonii meal supplementation interval on the productivity and carcass characteristics of broiler chickens. Hoodia gordonii meal supplementation interval had no effect (P > 0.05) on feed intake, growth rate, live weight, feed conversion ratio and all carcass characteristics except fat pad of broiler chickens. Daily supplementation with 300 mg of Hoodia gordonii meal/bird reduced fat pad weights of the chickens by 18 %. This could not be explained in terms of differences in feed intake, digestibility, or growth rate.     

Effect of age and season on semen quality parameters in Sahiwal bulls

The objective of the study was to determine the effect of season, period, age, bull, and ejaculate on semen quality in Sahiwal bulls. Semen production records from 1996 to 2006 of 5,483 ejaculates from 46 Sahiwal bulls maintained at Artificial Breeding Complex, NDRI, Karnal, India were analyzed using least square analysis of variance by LSML software package. The overall least squares means of ejaculate volume (VOL), total volume per day (VOLD), mass activity (MA), initial motility (IM), sperm concentration per ml (SPC), and sperm concentration per ejaculate (SPCE) were 3.79 ± 0.02 ml, 5.81 ± 0.06 ml, 2.32 ± 0.01, 55.47 ± 0.001%, 766.69 ± 5.50 × 10⁶/ml and 3023.25 ± 30.15 × 10⁶, respectively. All semen traits (VOL, VOLD, MA, IM and SPCE) were significantly (P < 0.01) affected by age groups, season and period, whereas season had significant effect on VOL at 5% level. During hot-humid season, highest value of VOL, VOLD, MA, IM, SPC, and SPCE were observed followed by summer and cold season. Highest value of VOL, VOLD, IM, and SPCE were observed during period-3 (2004–2006), whereas highest value of MA and SPC were observed during period-1 (1996–1999). However, lowest magnitude of MA, IM, SPC, and SPCE during period-2 (2000–2003) was observed. Ejaculate characteristics like VOL, VOLD, and SPCE increased with the increasing age of bull up to 5 years and then decreased. Significant (P < 0.01) bull to bull variation was found in VOL, VOLD, MA, IM, SPC, and SPCE traits. First ejaculate had significantly (P < 0.01) higher MA, IM, SPC, and SPCE. Hence, it could be concluded that during rainy season and period-1 and period-3 the quality of semen is quantitatively and qualitatively good. Better quality semen was obtained up to 5 years of age in Sahiwal bulls.     

Effects of genotype and population density on growth performance,carcass characteristics,and cost-benefits of broiler chickens in north central Nigeria

The influence of genotype and stocking densities on growth performance, carcass qualities, and cost-benefits of broilers were examined in a 28-day trial. Two hundred and seven 4-week-old birds each of Anak Titan and Arbor Acre hybrid broiler types were randomly assigned to three stocking density treatments of 8.3, 11.1, and 14.3 birds/m² in a 2 × 3 factorial arrangement. Final body weight, average weekly body weight and average weekly feed intake were affected (P < 0.05) by strain, with higher means recorded for Arbor Acres. However, average weekly body weight gain and feed conversion ratio were similar (P > 0.05) in both genetic groups. The effect of placement density on some growth parameters did not follow a linear trend. Arbor Acres had significantly (P < 0.05) higher relative (%) fasted body, carcass, back, neck, and wing weights compared to Anak Titans. Housing density effect (P < 0.05) was observed for relative (%) fasted body, shank, and wing weights of birds. However, the relative weights of visceral organs of birds were not significantly (P > 0.05) influenced by genotype and housing density. The economic analysis revealed that higher gross margin was recorded for Arbor Acres compared to Anak Titans (€2.76 versus €2.19; P < 0.05, respectively). Conversely, stocking rate did not exert any influence (P > 0.05) on profit margin. Genotype × stocking density interaction effect was significant for some of the carcass indices investigated. It is concluded that under sub-humid conditions of a tropical environment, the use of Arbor Acre genetic type as well as a placement density of 14.3 birds/m² appeared to be more profitable.     

Fattening performance of purebred and crossbred lambs from fat-tailed Kurdi ewes mated to four Iranian native ram breeds

A crossbreeding experiment was carried out to determine the sire breed effects on fattening performance of fat-tailed lambs. Rams from four Iranian fat-tailed sheep breeds, namely Kurdi (K), Afshari (A), Chaal (C) and Sanjabi (S) were mated to Kurdi ewes producing 454 progeny of four genotype groups (KK, AK, CK and SK). A total of 80 lambs comprising ten female and ten male lambs from each genotype group were used in a fattening experiment during a period of 88 days. Genotype of the lamb had significant effect on average dry matter intake (ADMI) (P < 0.05). SK lambs had the lowest ADMI. Average daily gain (ADG) and food conversion ratio (FCR) were not influenced by genotype of the lamb. Sex of the lamb had significant effect on both ADG and FCR (P < 0.01). Slaughter weight (SLW), hot carcass weight (HCW), cold carcass weight (CCW) and daily carcass gain (DCG) were not affected by lamb's genotype. However, genotype had significant effect on dressing percentage, carcass loss percentage (P < 0.01), carcass length (CL), leg circumference (LC), carcass compactness (CC) (P < 0.01) and carcass density (CD) (P < 0.05). Carcass width (CW) and leg length (LL) were not affected by lamb's genotype. Sex of the lamb had significant effects on CL, CW, LC, CC, CD (P < 0.01) and LL (P < 0.05). The results indicated the existence of sire breed difference for daily dry matter intake and carcass conformation in the fat-tailed sheep.     

Genetic analysis of growth and egg production traits in synthetic colored broiler female line using animal model

Tropical Animal Health and Production - Variance and genetic parameters were estimated for growth and production traits of synthetic broiler female line (PB-2) using REML animal model to delineate...     

Performance and carcass measurements of ewe lambs reared in a feedlot and fed wheat (<Emphasis Type="BoldItalic">Triticum durum</Emphasis> Desf.) middlings total mixed rations in the summer season

The effect of total mixed ratios containing wheat middlings (WM) as a corn grain substitute on the growth performance and carcass traits of Comisana ewe lambs was evaluated. Forty ewe lambs, with average live body weight of 13 ± 0.3 kg (mean ± SEM), were allocated randomly to two isocaloric and isonitrogenous diets for 50 days. Control diet contained 400 g/kg of dry matter (DM) of corn as the main starchy source, whereas experimental diet contained 600 g/kg DM of WM. In vivo nutrient apparent digestibility of the two diets was determined using Comisana rams (mean body weight, 65 ± 2.3 kg) and indicated significant (P < 0.05) differences for neutral detergent fibre, acid detergent fibre, cellulose and hemicellulose fractions. Results from the trial using Comisana ewe lambs showed that growth traits were unaffected by dietary treatments as well as none of the carcass measurements examined (P > 0.05). These findings indicate that WM results as a suitable feed ingredient for growing ewe lambs that can be a satisfactory substitute to conventional grain source.     

Growth performance and carcass characteristics of indigenous Mukota pigs of Zimbabwe

Carcass quality characteristics are essential in affecting grading and revenue that pig producers realize. No information is available on the grading of carcasses in indigenous Mukota pigs of Zimbabwe. The objective of this study was to determine the influence of genotype (Mukota and Large White × Mukota) and sex on post-weaning growth performance and carcass traits of pigs fed maize cob-based diets. All pigs were weighed at 2-week intervals to estimate average daily gain, dressing percentage (DP), and carcass lengths. Backfat thickness was also measured. Males had higher body weight gains than females (P < 0.05). Growth rates for Mukota (0.31 ± 0.010) and crossbred (0.41 ± 0.030) pigs were lower in the cool season than the other seasons (P < 0.05). Body weights were consistently higher in the crossbred than in the Mukota pigs (P < 0.05). Mukota pigs showed a peak growth between 12 and 14 weeks post-weaning (P < 0.05). The DPs were 0.70 and 0.73 for the Mukota and crossbred pigs, respectively (P < 0.05). Crossbred pigs had longer (P < 0.05) carcasses than Mukota (655.5 ± 1.68 versus 507.2 ± 0.92 mm). Although there were no differences in the backfat thickness between males and females of the crossbred pigs, Mukota males had thicker backfat than the females (P < 0.05). Crossbreeding is, therefore, significant in improving carcass grades of Mukota pigs.     

Heterosis and combining ability for body weight in a diallel cross of three chicken genotypes

The aim of the study was to evaluate heterotic and combining ability effects for growth in nine chicken genotypes. A 3?×?3 complete diallel mating system involving two indigenous breeds named Venda (V) and Naked Neck (N) and one commercial broiler breed named Ross 308 (R) were used. The nine genetic groups of crosses were reared up from hatch to 13 weeks of age in deep litter open house. Body weights of 180 chicks (20 chicks per genetic group), recorded at 0, 3, 5, 7, 9, 11, and 13 weeks of age, were used to estimate heterosis, general combining ability (GCA), and specific combining ability (SCA). Results showed that the Ross 308 had the heaviest body weight at all weeks of measurement except for hatch. With respect to crosses, the V × R and its reciprocal cross, R × V had the heaviest body weights at 13 weeks. Heterosis estimates for body weight were higher in the Venda male × Ross 308 female and Venda male and Naked Neck female crosses. GCA was significant (P?≤?0.01) for body weight from hatch to 13 weeks of age while SCA and reciprocal effects were both significant (P?≤?0.05) for body weight at all ages of measurement except for hatch. The Ross 308 gave the highest positive effect of GCA for body weight except for hatch. V × N gave the highest and positive effects of SCA for body weight.     

Growth performance and carcass characteristics of broiler chickens fed diets supplemented with graded levels of charcoal from maize cob or seed of <Emphasis Type="Italic">Canarium schweinfurthii</Emphasis> Engl

Growth performances and carcass characteristics of broiler chickens fed diets supplemented with graded levels of Canarium schweinfurthii Engl seed (charcoal A) or maize cob (charcoal B) were studied using a total of 110 3-week-old male chicks. 11 experimental diets including a control and other containing either 0.2, 0.4, 0.6, 0.8 or 1% charcoal from C. schweinfurthii Engl seed (A_0.2, A_0.4, A_0.6, A_0.8, and A_1%, respectively) or from maize cob (B_0.2, B_0.4, B_0.6, B_0.8, and B_1%, respectively) supplements were used. Each of the diets was fed to ten individually birds caged in a completely randomized design. Results indicated that birds fed 0.2, 0.4, and 0.6% of either charcoal A or B had significantly (P < 0.05) higher final body weights as compared to control birds, while, above 0.6% slightly depressed average final body weights and weight gain. The best growth performance was achieved with 0.2% inclusion of charcoals. There was no significant (P > 0.05) influence of charcoal B on the overall feed intake. Only the B_0.6 feed significantly (P < 0.05) improved feed conversion ratio as compared with the control. Dressing percentage, liver weight and abdominal fat were not significantly (P > 0.05) affected by charcoal. However, there was a significant (P < 0.05) reduction in gizzard weight with charcoal B. Charcoal had no significant (P > 0.05) influence on intestine length and weight. More than 0.6% of charcoal A significantly (P < 0.05) depressed intestine density. It was concluded that under the conditions of this study, charcoal from maize cob or Canarium seeds could be used to improve growth performances and some carcass traits in broiler chickens.     

Effects of different levels of dried sweet potato (<Emphasis Type="Italic">Ipomoea batatas</Emphasis>) leaves inclusion in finisher ration on feed intake,growth, and carcass yield performance of Ross broiler chicks

The effect of supplementation with increasing levels of dried leaves of sweet potato (Ipomoea batatas) on feed intake, body weight gain, and carcass yield characteristics of finisher Ross broiler chicks was studied at Haramaya University, Ethiopia. Three hundred Ross broiler chicks aging 29 days and weighing 540 ± 5.28 g (mean ± SD) were randomly distributed to 15 pens, each with 20 chicks, representing five treatment rations each with three replications. Dietary treatments consisted of inclusions of dried leaves of sweet potato at levels of 0, 50, 100, 150, and 200 g/kg DM for treatments T1, T2, T3, T4, and T5, respectively. The experiment lasted for 28 days, during which, dry matter intake (DMI), body weight gain, and feed conversion efficiency; carcass yield characteristics; and weights and lengths of different parts of gastrointestinal tract were measured. Data were subjected to statistical analysis using SAS (1998). Inclusion of dried leaves of sweet potato at the level of 200 g/kg DM resulted in lower (P < 0.01) daily DMI as compared to chicks in control diet (T1). The daily body weight gain declined (P < 0.01) when the level of dried leaves of sweet potato in the diet was 150 and 200 g/kg DM. Inclusion of dried leaves of sweet potato up to 100 g/kg DM did not affect (P > 0.05) eviscerated carcass weight, and weights of drumstick with thigh and breast meat were not affected (P > 0.05) by inclusion of dried leaves of sweet potato up to 150 g/kg DM. The results of this study revealed that inclusion of dried leaves of sweet potato up to 100 g/kg DM in the finisher ration might be considered as the optimum level of supplementation when chickens are sold on live weight basis, but if birds are sold on eviscerated carcass weight basis, inclusion up to 150 g/kg DM might be economically feasible as it produced higher carcass yield components.     

Wool characteristics in the third generation of Arkharmerino × Ghezel and Arkharmerino × Moghani crossbreed sheep

This investigation was conducted to evaluate the comparative productive performances and effect of some environmental factors on wool characteristics of Arkharmerino × Ghezel (Ar × Gh) and Arkharmerino × Moghani (Ar × Mo) crossbreed sheep. The mid-side fleece samples taken from animals during 2 years (2007–2008) were analyzed. Each sample was measured for average fiber diameter, fiber diameter variability, staple length, proportion of medullated fiber, proportion of kemp, and comfort factor. The comparative values for these fleece characteristics in F₃ generation Ar × Gh were 28.78 ± 0.48 μm, 36.84 ± 1.16%, 11.94 ± 0.35 cm, 7.07 ± 0.93%, 1.02 ± 0.23%, and 68.93%, respectively; while those traits were 29.79 ± 0.43 μm, 41.86 ± 1.16%, 11.96 ± 0.37 cm, 8.13 ± 1.06%, 2.71 ± 0.45%, and 63.33 ± 3.66% for Ar × Mo, respectively. The effects of genotype, sex, birth type, and year of birth were analyzed. Genotype had a significant (P < 0.01) effect on average fiber diameter and proportion of kemp, and Ar × Gh crossbreeds had lower diameter with less proportion of kemp. The two differences in fiber characteristics that were attributable to sex were fiber diameter variability and proportion of medullated fiber, and females had higher measure than males for both traits. Statistical analysis showed that crossbreeding with Arkharmerino generally had positive effects on the fleece favored to be used in the hand woven authentic carpet production.     

Carcass conformation and cut composition of Creole goat from Guadeloupe

Carcass data base of 164 Creole male goats was used in order to provide factual data on the carcass conformation. Standardised procedures of carcass measuring and cutting were followed. The European official grid of light lamb is implemented for meat goat in the French West Indies and included five levels. Weights of carcass, cuts and tissues, quality scores and linear measurements were analysed. Feeding system, age at slaughter and weight were taken into account for statistical analysis. There were significant differences among carcass conformation classes (CC) for many traits except for the fat score, leg length and compactness ratio (carcass width on length): 2.2, 34.5 cm and 0.30 on average, respectively. The values of chilled carcass weight and yield and the carcass linear measurements steadily increased until conformation class 4 or 5: 6.7 to 11.2 kg, 49% to 55% and 52.4 to 58.0 cm carcass length. For the weights of carcass cuts, significant differences appeared between two groups: classes 1 and 2 vs. classes 3, 4 and 5. Regardless of the carcass weight, the distribution of prime cuts remained similar. The indices calculated on a weight basis (kg/cm), either for the carcass or the leg, increased significantly (P < 0.01): with 54% and 63% difference between the two extreme classes, respectively. The muscle, bone and fat proportions in the shoulder did not vary between CC with 0.72, 0.22 and 0.06, respectively. Corresponding traits in leg were 0.74, 0.23 and 0.03; the last two were different (P < 0.05) from class 1 to class 5. The muscle/bone ratios calculated either in shoulder or in leg ranged from 3.1 to 3.6 (P > 0.05).     

Combining abilities among four breeds of chicken for feed efficiency variation: a preliminary assessment for chicken improvement in Nigeria

General and specific combining abilities for feed efficiency in 5,191 chicks from a combination of four breeds of chickens, (Anak Titan (A), Alpha (B), Giriraja (G), and normal indigenous (N) chickens) were examined by means of diallel analysis. The analysis revealed that Anak Titan had the highest general combining ability of 0.07 ± 0.00 while the least was Alpha with a value of −0.09 ± 0.00. The results of the specific combining abilities (SCA) reveal a high value of SCA in GN cross with a value of 0.08 ± 0.01 while the least value was −0.12 ± 0.01 (AN cross). It is recommended that an improvement process for feed efficiency that involves all the breeds should be adapted using a reciprocal recurrent selection or modifications of it. Anak Titan will be a good sire line and the GN cross a good dam line to use in such an improvement program.     

Growth performance of Nigerian local chickens in crosses involving an exotic broiler breeder

Six-hundred-and-seven-day-old chicks were generated from Nigerian local chickens consisting of three genotypes (Normal-feathered; Frizzled-feathered; Naked neck) and an exotic broiler breeder (Anak Titan) to evaluate growth performance for possible meat-type chicken development. Growth parameters measured were body weight, breast girth and keel length on weekly basis for 20 weeks. Effects of sire, dam and chick genotypes were significant (P < 0.001) on growth traits. At week 20, chickens sired by the Anak Titan weighed 1,614.82 g followed by Normal-feathered local chickens with body weight of 1,211.32 g. Progenies of Anak Titan and Naked neck dams weighed 1,761.96 and 1,292.80 g at week 20, respectively. Among purebreds, Anak Titan weighed 35.05 g at day-old and had heaviest body weight of 2,360.29 g at 20 weeks compared to the three local strains. The average body weights for the crossbred, Normal-feathered×Anak Titan at day-old and week 20 were 36.39 and 1,577.63 g, respectively. This was followed by Anak Titan×Naked neck with 33.32 g at day-old and 1,514.14 g at week 20. Sex had significant effect (P < 0.05) at weeks 16 and 20 with the males having higher mean values than their female counterparts. This study revealed that crosses involving Anak Titan sire×Naked neck dam had highest growth performance, and there was no strain differences among the growth performance of purebred Nigerian local chickens.     

Effect of crossbreeding on fertility,hatchability and embryonic mortality of Nigerian local chickens

A total of 970 eggs were collected from matings involving three genotypes of Nigerian local chickens (Normal-feathered, Frizzle-feathered and Naked neck) and one exotic broiler breeder strain (Anak Titan) to evaluate the effect of crossbreeding on fertility, hatchability and embryonic mortality. Mating was achieved through artificial insemination. Sire genotype significantly (P < 0.05) affected percent fertility and percent dead-in-shell. Naked neck sire genotype had the highest dead-in-shell (19.5%) with the least being 7.5% for Frizzle-feathered chickens. Frizzle-feathered sire genotype had the highest fertility (90.5%) and hatchability (91.4%). Dam genotype had a significant effect (P < 0.01) on fertility and hatchability, with Anak Titan dam having the highest fertility and hatchability of 88.2% and 94.6%, respectively. Fertility and hatchability were significantly (P < 0.05) influenced by the interactive effect of sire and dam genotypes with Frizzle-feathered × Anak Titan having 98.5% fertility and 96.8% hatchability. Both straight and reciprocal crosses involving Frizzle-feathered genotype and Anak Titan resulted in higher mean values for fertility and hatchability when compared to crosses involving the other two local chicken genotypes. This result suggests that the use of the Frizzle-feathered genotype appears to be more desirable in fertility and hatchability trials.     

Performance and meat quality traits of beef heifers fed with two levels of concentrate and ruminally undegradable protein

The effects of two levels of concentrate and ruminally undegradable protein (RUP) on performance, intake, digestibility, carcass characteristics, meat quality traits, and commercial cuts yield were assessed. Twenty crossbred heifers (240 kg average body weight) were used. At the beginning of the trial, four animals were slaughtered as reference group and the 16 remaining animals were randomly assigned to four treatments, in a 2 × 2 factorial design: two levels of concentrate (40% and 80%, dry matter (DM) basis) and two levels of RUP (48.79% and 27.19% of CP). At the end of the trial, all the animals were slaughtered. There was no interaction (P > 0.05) between concentrate and RUP levels. Dry matter intake and nutrients digestibility was not affected (P > 0.05) by RUP level. Heifers fed the highest RUP level had greater (P < 0.05) average daily gain (ADG). Concentrate level did not affect (P > 0.05) DMI and ADG. Heifers fed diets with 80% concentrate had greater intake of TDN and EE, and lower intake of NDF (P < 0.05). The digestibilities of all nutrients, except the NDF, were greater (P < 0.05) for the 80% concentrate diets. The RUP levels did not affect (P > 0.05) the carcass characteristics and carcass gain composition. Heifers fed 80% concentrate diets had larger (P < 0.05) longissimus muscle area and lower gain of bones (P < 0.05). Concentrate level did not affect (P > 0.05) the composition of carcass gain. There was no effect (P > 0.05) of RUP and concentrate levels on meat quality traits and commercial cut yields.     

杜洛克、大白、长白猪的生长和肉用性状杂交效果研究

为筛选优化杂交组合,进行了杜洛克（杜）、大白（大）、长白（长）品种间杂交试验,测定了不同品种组合的生长速度、饲料转化率、胴体和肉质性状及其杂种优势率。结果表明,杜洛克、父系大白猪作终端父本与长大杂母猪杂交,其后代的日增重、饲料转化率、屠宰率、胴体长、眼肌面积、后腿比例、瘦肉率及肉质等主要性状均无显著差异。     

Growth and carcass traits of Creole goats under different pre-weaning,fattening and slaughter conditions

Data of 198 male Creole kids were analysed to assess the main non-genetic sources of variation of their meat abilities. Basal diet was composed of tropical pasture (28 days): in FD (forage diet), kids received no supplement; in group MD (mixed diet) they were offered 360 g/day pellet, while in group PD (pasture diet) kids were reared at pasture without supplementation. Given a regular four-month interval of weaning within the flock, fixed ages at slaughter (AS) were 7, 11 and 15 months. Three slaughter weights (SW) were compared 17–18, 21–22 and 25–26 kg. The growth levels before weaning and the season of birth effects were added in the statistical analysis. The use of MD has a significant (P < 0.05) effect on almost all the body and carcass traits: 85% more ADG and carcass weight. The weights of fat tissues increased but represented only 4% of empty body weight. As expected, there were significant (P < 0.05) differences within the SW and AS classes that are discussed. Range of variations allow for suggesting further experiments or practical recommendations. The initial results: carcass yield (55%), conformation score (more than 3), fat cover score (less than 3), proportion of primal cuts (63%) or muscle/bone ratio (3–4 points) are a good incentive for the local sector.     

Analysis of size and conformation of native Creole goat breeds and crossbreds used in smallholder agrosilvopastoral systems in Puebla,Mexico

Liveweight (LW) of does and bucks of the native Creole goat breed and crosses of Creole does and Nubian bucks, aged 1.5–5 years, were recorded and body traits including: head length (HL), head width (HW), body length (BL), trunk length (TL), chest girth (CG), abdominal perimeter (AP), rump length (RL), and height at withers (HW) were measured to develop equations for predicting LW from the body measurements. Weight, sex, breed and kidding date of 354 kids were recorded at birth, and LW of the kids was measured monthly for one year to determine the effect of kidding season on growth rate. Bucks had higher (p < 0.05) body measurements than the does (HL 15.1 ± 0.1 vs 16.6 ± 0.2 cm; BL 97.6 ± 0.4 vs 104.6 ± 1.2 cm; CG 78.8 ± 0.4 vs 79.9 ± 1.0 cm; AP 82.4 ± 0.5 vs 87.2 ± 1.1 cm; HW 62.7 ± 0.4 vs 70.1 ± 0.8 cm). With the exception of TL, F₂ does had higher (p < 0.05) body measurements and LW (28.8 ± 1.5 vs 27.7 ± 0.5 kg) than Creole does. The body traits of the F₁ does were similar (p > 0.05) to those of Creole does with the exception of HL, BL and HR. The F₂ kids were heavier (p < 0.05) at birth (3.31 ± 0.1 vs 2.60 ± 0.1 kg) and grew faster than the Creole kids. Male kids were heavier (p < 0.05) at birth (3.21 ± 0.10 vs 2.73 ± 0.13 kg), and grew faster than female kids. Season had a significant effect on birth weight. The results showed that LW of Creole goats and Creole × Nubian does could be estimated in the field using body traits. Birth weight and growth rate of kids could be improved by management practices that affect season of kidding.