Comparison of the Brahman and Friesian breeds as sires for beef production in New Zealand

Transcription

1 New Zealand Journal of Agricultural Research ISSN: (Print) (Online) Journal homepage: Comparison of the Brahman and Friesian breeds as sires for beef production in New Zealand C. A. Morris, K. R. Jones, J. A. Wilson & T. G. Watson To cite this article: C. A. Morris, K. R. Jones, J. A. Wilson & T. G. Watson (1992) Comparison of the Brahman and Friesian breeds as sires for beef production in New Zealand, New Zealand Journal of Agricultural Research, 35:3, , DOI: / To link to this article: Published online: 30 Jan Submit your article to this journal Article views: 539 Citing articles: 7 View citing articles Full Terms & Conditions of access and use can be found at

2 New Zealand Journal of Agricultural Research, 1992, Vol. 35: /92/ $2.50/0 The Royal Society of New Zealand Comparison of the Brahman and Friesian breeds as sires for beef production in New Zealand C.A.MORRIS K. R.JONES J.A. WILSON T. G. WATSON N. Z. Pastoral Agriculture Research Institute Ltd Ruakura Agricultural Centre Private Bag 3123, Hamilton, New Zealand Abstract A comparison of Brahmans and Friesians as sire breeds was carried out with crossbred cows over three calf crops (birth years ) to investigate differences in growth, internal parasite burdens, carcass weight and composition, and early female reproduction under temperate pastoral conditions in New Zealand. All six Brahman bulls available in New Zealand by artificial insemination were used, alongside eight Friesian bulls, generating 229 calves. Steers were slaughtered at 18 months of age, whereas heifers were slaughtered at 2.5 and 3.5 years (1985 animals), 2.5 years (1986 animals), and 1.5 years (1987 animals).gestation lengths, dates of birth, and birth weights of Brahman-sired calves were respectively 8.9 ± 1.0 days longer, 12.3 ± 2.1 days later, and 5.5 ± 0.9 kg heavier than those of the Friesian-sired calves. Liveweights from weaning to slaughter, however, were not significantly different. Faecal egg counts (FEC) during a challenge period from weaning (4 months) to 9 months of age showed that the Brahman-sired cattle generally had lower values. Repeatabilities of FEC and loge (FEC) were 0.33 ± 0.08 and 0.21 ± 0.08, respectively. Carcass weight was 4.2% greater for Brahman-sired than Friesiansired animals (P < 0.01). For carcass composition at fixed age, Brahman-sired animals had significantly heavier hind-quarters and lighter bones A92004 Received 30 January 1992; accepted 20 July 1992 (both traits as a percentage of side weight) than Friesian-sired animals. At fixed carcass weight, the two breeds were similar in fat depth and in the weight of trimmed fat in the carcass; eye muscle area, and the weights of hind-quarter and of saleable meat were significantly greater whereas the weight of bone was significantly less in Brahman-sired than Friesian-sired cattle. For pregnancy rate subsequent to a 2-month mating period, Friesian-sired heifers had a higher value (P < 0.01) as yearlings than Brahman-sired heifers (91 versus 27% in calt), but there was no significant difference in pregnancy rate in 2-year-olds as a result of breed of sire. Keywords beef cattle; growth; carcass composition; faecal egg count; crossbreeding; breeds; terminal sires; Brahman; Bas indicus; Friesian; Bas taurus; pregnancy INTRODUCfION There are no published comparisons in New Zealand of Brahman (Bas indicus) cattle with Bas taurus breeds or crosses. Under tropical conditions, Frisch & Vercoe (1984) have shown that B. indicus were superior in performance to B. taurus cattle when there were internal or external parasite challenges, heat stress, or seasonal feed shortages. A comparison of Brahman versus Friesian (and other) terminal sire breeds has been reported in New South Wales, but under subtropical conditions (Barlow & O'Neill (1980) and subsequent reports cited later in this papcr). Cundiffetal. (1986),however, have demonstrated acceptable performance of Brahmans and other B. indicus breeds as terminal sires when evaluated under American temperate rangeland conditions. The present study was designed to compare, over 3 years, the Brahman breed with the Friesian breed under temperate conditions in New Zealand. The latter was one of the terminal sire breeds already included in the New Zealand beef breed comparisons reported by Everitt et al. (1980) and Baker et al. (1990).

3 278 New Zealand Journal of Agricultural Research, 1992, Vol. 35 MATERIALS AND METHODS Management and experimental design All six Brahman bulls available for use by artificial insemination (AI) in New Zealand were evaluated in this experiment, alongside Friesian bulls which were widely available by AI to beef or dairy fanners. Over the three mating years, , eight Friesians were compared with the six Brahmans. Table 1 gives the numbers of bulls used per year, along with the numbers of calves generated in the experiment. Crossbred cows were used in this experiment, consisting of those groups born in at Tokanui Research Station, Te Awamutu, as part of the Ruakura Beef Breed Evaluation (Baker et al. 1990). When they calved in at Tokanui to AI by the Brahman and Friesian terminal sire breeds under evaluation here, these cows as dams ranged from 8 to 13 years in age. All cows were allocated in balanced manner to bulls of the two breeds each year with respect to breed of cow, age, calving date, and lactation status. Calves in each calf crop were born over about a 2-month period in late winter/early spring. Calves were tagged, identified to dam, and weighed within 24 h of birth, and males were castrated. All calves were weaned on one day when about 130 days of Table 1 Numbers of sires and animals. Year of birth Breed Item of sire a Total No. of sire groups B b F b No. of calves bomc B F Difficult births B F Perinatal calf deaths B F No. of calves weaned B F No. with drench withheld B d F d No. of carcasses dissected B F a B = Brahman; F = Friesian b Sires repeated across years were counted once only in the overall total. C Calves born alive or dead. d Only males in 1985; a random sample half in age. Young stock of both sexes were then grazed in one management group. Heifers continued through to the end of October (13-14 months of age), and steers to the second aututnn (about 18 months of age). The group was rotated frequently over a suite of paddocks. Faecal egg counts As a result of the faecal egg count (FEC) comparisons of B. indicus and B. taurus in the tropics (Frisch & Vercoe 1984) indicating breed differences after weaning, we repeated their comparisons under our temperate pastoral conditions. Anthelmintic drench was administered at 2 months of age but was withheld from the steers born in 1985 at weaning in January (4 months of age). Faecal samples were obtained for FEC comparisons in January and monthly until June, at which time the drenching regime was resumed. For animals born in 1986, a sample half of the animals of both sexes was allocated at weaning in January to the "withheld drench" group, and the remainder were drenched at weaning and then every 6-8 weeks until mid July when all animals were again drenched. Faecal samples were obtained for FEC from all animals before the drenching day in February, March, May, and July. Animals from the two drench treatments were grazed together. Blood samples were taken from all animals on the same days as faecal sampling was carried out, for the determination of plasma pepsinogen activity. Pepsinogen is a measure of the damage caused to the abomasal wall by the Ostertagia parasite. Faecal consistency scores were also recorded on all faecal samples from animals born in Slaughter protocol for steers Steers were allocated to slaughter at the Ruakura Experimental Abattoir at about 18 months of age. There were three slaughter days for the steers born in 1985 and two slaughter days each year thereafter. Animals were randomised to day according to sire x breed of dam and date of birth. Table 2 shows the numbers of steers experimentally slaughtered. Mating and slaughter protocol for heifers and cows Heifers born in 1985 and 1986 were naturally mated as yearlings ( months of age) in randomised single-sire mating groups. The 1987 birth group was

4 Morris et al.-brahman and Friesian breeds as sires for beef production 279 allocated to slaughter at the Ruakura Experimental Abattoir at months of age without prior mating. The 1985 and 1986 birth groups of heifers calved at 2 years of age; a further 12-month cycle was repeated for the 1985 birth group. Pregnancy diagnosis data were obtained each autumn by palpation per rectum. Table 2 gives details of the ages and physiological stages at slaughter for each birth group. Thus, all the 1985 and 1986 birth groups of females were slaughtered after weaning their first or second calf, with the exception of seven animals (Table 2) which turned out to be non-pregnant at calving time, or produced dead calves, or had a calf die soon after birth (these cows were allocated to slaughter soon after calving). There were seven slaughter groups of females, respectively 4, 2, and 1 groups for those born in 1985, 1986, and Females of the two breeds were managed together at all times, within physiological status. Thus, nonpregnant animals of both breeds were grazed together as rising 2-year-olds, whereas pregnant animals of both breeds were grazed together as another management group. Abattoir data A full liveweight was- obtained at Tokanui immediately before transport to the Ruakura Experimental Abattoir, and an empty liveweight (EL W) was taken immediately before slaughter after Table 2 Numbers of animals from which carcass data were obtained. Age at Year of birth slaughter Physiological Sex (mo) status " 1987 All Steers Heifers Unmated Post-calving Post-weaning Post-calving Post-weaning Subtotal Total " A further 18 females were withdrawn from the 1986 birth group at 18 months of age, being non-pregnant at the end of joining; all were Brahman-sired, so they provided no opportunity for carcass comparisons with Friesian-sired females. an overnight fast. The hot-carcass weight (HCW) was recorded immediately after slaughter. Each carcass was quartered and the left side and the left hind-quarter were weighed. Fat depths were taken using a, ruler on the quartered, chilled carcass at the 10/11th rib in Positions C, D, and E on the eye muscle (Musculus longissimus) (ARC 1965), and length and breadth measurements (A and B) were taken on the cross-section of the muscle (ARC 1965). The weights of the three components, saleable meat, bone, and trimmed fat, were recorded on the left side of each carcass, with cutting according to the New Zealand commercial system (Everitt & Jury 1964), after removal of perinephric and retroperitoneal fat. An export grade was allocated visually to each hot carcass by a meat inspector, as described by Woods et al. (1986), where Grades M, Lt, L2, P, K, G, and T represented increasing levels of subcutaneous fat. Because of small numbers of carcasses in most grades, results were subsequently pooled and classified as lean (0-3 mm subcutaneous fat, combining Grades M and L), prime (4-7 mm, Grade P), or fatter (> 7 mm, Grades 1(, G, and n. In the present data, carcasses of the lean group averaged 11.2% trimmed fat weight in heifers (13.4% in steers), the prime group averaged 17.6% (18.8%), and the fatter group averaged 20.9% (24.2%). Traits analysed The following traits were analysed: gestation length; date of birth; weights at birth, weaning, 9 months, 13 months, and months of age; FEC at monthly intervals (calves born in 1985) and alternate monthly (calves born in 1986); faecal consistency score (calves born in 1986), coded 2 to 5, with 2 being dry and 5 being wet; plasma pepsinogen activity (calves born in 1986); pregnancy diagnosis data (011) for two seasons of matings for animals born in 1985 and for one season for animals born in 1986; full liveweight (pre-slaughter); EL W (preslaughter); HCW; dressing-out percentage, calculated as 100 x HCW/EL W; fat depth (average of measurements C, D, and E); eye muscle area (taken as the product of measurements A and B); left hind-quarter weight; left hind-quarter weight as a percentage of left side weight; saleable meat weight in left side; bone weight in left side; trimmed fat weight in left side; saleable meat, bone, and trimmed fat weights each as a percentage of left side weight; and export grade (lean, prime, or fatter).

5 280 New Zealand Journal of Agricultural Research, 1992, Vol. 35 Data analysis methods Records (apart from calf survival data, pregnancy data, and carcass grades) were analysed using the Genstat (1988) computer programme. For data on gestation length, date of birth, and liveweights to 18 months of age, the model consisted of fixed effects for breed of sire, breed of dam (11 groups, as described by Morris et al. 1987), year of birth! treatment group, sex of calf, year of birth of dam, and (for weights) a covariate for date of birth. The year ofbirthltreatment group consisted of four levels, namely 1985, 1986-drenched group, undrenched group, and The drench treatment for animals born in 1985 was applied to steers only, and the treatment and sex effects were therefore confounded, whereas the treatment effect was estimable over both sexes of animals born in Two-factor interactions were also tested, but were generally found to account for a very small proportion of the sums of squares. and were not considered further (except the interaction of breed of sire with sex for birth weight, described later). Similar models were also used for FEC data from the frrst two calf crops (except that there were no data from heifers born in 1985), and for faecal consistency and pepsinogen activity (records only on 1986 animals). The egg counts were analysed on the natural scale and after transformation to a loge (FEC + 1) scale, to allow for the skewness on the natural scale. An additional analysis using restricted maximum likelihood (REML) procedures (Patterson & Thompson 1971) was undertaken on pepsinogen and all faecal traits from all sample days, fitting "day" as an extra fixed effect and "animal" as a random effect. A similar REML model was then applied to sample days from March to June in the frrst year and from May to July in the second year (undrenched animals only), to estimate betweenanimal repeatability. The sample dates qualifying for inclusion of FEC in the repeatability analysis were determined according to FEe means (i.e., where the mean for the sample day was > 250 eggs/g). The pregnancy data from yearlings and 2-yearolds were analysed using chi-square, with a 2 x 2 contingency table. Calf survival data were also analysed in this way. For pre-slaughter weighlst and abattoir data, the analysis of varfarice model consisted of effects for breed of sire, breeq"of dam, slaughter group (14 levels, i.e., combinations of sex, age at slaughter (yr), and year ofbirtb groups), the interaction of breed of sire and slaughter group, and a covariate for age at slaughter (days). From a preliminary set of analyses it had been determined that there were no Significant interactions between slaughter group and the covariate for age in days at slaughter (deviation from average age of the slaughter group). In instances where the interaction of breed of sire with slaughter group was not significant, this effect was discarded from the estimation step. A further set of analyses was also carried out, with an alternative covariate (hot-carcass weight); this model was applied only to average fat depth, eye muscle area, left hindquarter weight, and weights of saleable meat, bone, and trimmed fat in the left side of the carcass. Finally, the carcass grade data were analysed using chisquare. RESULTS Calf numbers, gestation length, date of birth, and liveweight traits Table 1 shows the numbers of calves born with difficulty, and the perinatal survival data. Both traits were similar for each breed of sire. However, a higher proportion (P < 0.05) of Friesian-cross than Brahman-cross calves survived from 2 days of age until weaning (100 versus 95.2%). Table 3 shows the breed-of-sire comparisons for gestation length, date of birth, and liveweight traits up to 18 months of age. Phenotypic standard deviations are also given, representing the residual standard deviation after fitting all fixed effects. Gestations were significantly longer by 8.9 ± 1.0 days in Brahman-sired than Friesian-sired calves. Corresponding dates of birth were even later for Brahman-sired than Friesian-sired calves because of Table 3 Least square means for the effects of breed ~ f sire on the growth performance of calves born in Trait Gestation length (d) Date of birth Birth wt (kg) Weaning w (kg) ~ 9-month wt (kg) 13-month wt (kg) I8-month wt (kg) Brahman (B) Friesian (F) Sep 29 Aug Diff. Phenotypic B-F SD 8.9 *** *** *** NS t NS NS 35.6 a Weaning at an average of 4 months of age. NS = not significant; *** = P < 0.001; t = P < 0.10.

6 Morris et al.-brahman and Friesian breeds as sires for beef production 281 poorer conception rates achieved using Brahman semen than Friesian semen on the dams. Birth weights, adjusted to a fixed date of birth, were 5.5 ± 0.9 kg (15%) greater for Brahman-sired than Friesian-sired calves. The difference was 0.4 kg greater still if not adjusted for date of birth. There was an interaction between sex of calf and breed of sire for birth weight, in that the breed difference was 3.1 kg in females but 7.2 kg in males (P < 0.05). Liveweights between weaning and 18 months of age were not significantly different between breeds of sire. The effects of breed of sire were also tested against the "sire within breed" effect as an error term, but none of the conclusions about the significance of the effects of breed of sire were changed. Faecal egg counts Table 4 shows the FEC results on the natural and logarithmic scales. The statistical tests shown were obtained from the log analyses. Where differences as a result of breed of sire were significant, the FEe values were always smaller for the Brahman-sired cattle. The REML analyses combining all sample days showed a significantly lower FEe value for Brahman-sired cattle in both years. The effects of drench treatment on liveweight (Le., drenched group minus undrenched group) for animals born in 1986 were 1.7, 6.2, 9.5, and 2.1 kg respectively, at weaning (the time of allocation to treatment), and at 9, 13, and 18 months of age. All contrasts between drench treatments were nonsignificant for liveweights. For animals born in 1986, the relationship between weight gain (from 4 to 13 months of age) and loge (FEC) was tested, usiilg FEC data from May, omitting earlier months because means were low, and omitting July to avoid the possibility of self-cure confusing the results. This regression of gain on loge (FEC) was not significant. By 18 months of age, when steers were slaughtered, abattoir data (calves born in 1986 only) showed a low mean FEC of 243 eggs/g. In the faecal samples obtained soon after weaning in the 1986 calf crop, Cooperia was the predominant species in untreated groups, ranging from 74 to 100% in bulked faecal cultures each sampling day, for breed of sire x treatment groups. The only exception was for Friesian-sired cattle at the May sampling, when 36% Cooperia, 24% Ostertagia, and 40% Trichostrongylus larvae were recovered. The estimates of repeatability for FEe, using data from undrenched animals and selected sampling days, were 0.35 ± 0.10 for those born in 1985 and 0.24 ± 0.17 for those born in 1986, giving a combined estimate of 0.33 ± Corresponding values for loge (FEC) were 0.19 ±O.09, 0.25 ±0.17, and 0.21 ± 0.08, respectively. Repeatability values (all sample days) for faecal consistency and pepsinogen activity were 0.25 ± 0.07 and 0.40 ± 0.07, respectively. From the REML analysis over all sample days, the effect of Brahman versus Friesian breeds of sire on faecal consistency was 0.28 ± 0.11 (P < 0.05). Brahman-sired animals thus had more watery faeces. The effect of drenching on faecal consistency (undrenched minus drenched) approached significance, averaging ± Breeds of sire did not differ in pepsinogen activity. The only significant effect on pepsinogen activity was that of sample day (P < 0.01), with adjusted means of 866, 1128, 1123, and 1003 ± 38 units respectively in the months of February, March, May, and july. Corresponding adjusted means for FEe were 84, 109, 559, and 332 eggs/g. Table 4 Least square means for the effects of breed of sire on mean faecal egg count (FEC). Year Month Brahman Friesian of when FECb FECb Log.,(x + 1) Phenotypic birth sampled" (x) (y) -loge(y + 1) SDc 1985 Jan NS 1.92 Feb NS 2.02 Mar t 2.12 Apr * 1.84 May ** 1.18 Jun NS 2.64 Combined d *** Feb O.94NS 2.12 Mar NS 1.64 May * 0.90 Jul NS 2.02 Combined d ** 1.99 " In first year of life; January = 4 months of age; in the 1985 group, only undrenched animals were evaluated, whereas in 1986 undrenched and drenched animals were evaluated (no significant differences found for the interaction between breed of sire and drench treatment). b Units of eggs/g c loge scale d Restricted maximum likelihood analysis, combining all sample days NS = not significant; * = P < 0.05; ** = P < 0.01; *** = P < 0.001; t = P < 0.10.

7 282 New Zealand Journal of Agricultural Research, 1992, Vol. 35 Pregnancy data from heifers Table 5 gives the pregnancy diagnosis results over two seasons for females born in 1985 and over one season for females born in Chi-square tests on the yearling mating data showed a much higher pregnancy rate (P < 0.01) for Friesian-sired than Brahman-sired heifers, averaging 91 versus 27% overall. For 2-year-old matings, pregnancy rates averaged 77.5% and did not differ between breeds of sire. Abattoir data Table 6 shows the comparison of breeds of sire for all abattoir traits, along with phenotypic standard deviations and regressions on age at slaughter. Apart from the percentage traits, regressions on age at Table 5 Pregnancy diagnosis results by breed of sire for 1985-born animals (two seasons) and 1986-born animals (one season). Year Age Brahman Friesian of (mo) at birth mating Empty Pregnant Total Empty PregnantTotai slaughter were significant for most traits. Breed of dam was significant for most traits, and slaughter group was significant for all traits (as expected because the "group" accounted for year of birth, sex, and age at slaughter combinations). Although the interaction of breed of sire and slaughter group was significant for most traits, the average breed of sire contrasts were little affected. Full and empty liveweights were similar for the two breeds of sire, whereas hot-carcass weight was significantly greater for Brahman-sired than Friesian-sired cattle. It followed that dressing-out percentage was greater for the former breed of sire. Fat depth and bone weight were both similar for the two breeds of sire, whereas eye muscle area, left hind-quarter weight, saleable meat weight, and trimmed fat weight were significantly greater for the Brahman-sired cattle. In these six comparisons it must be remembered that Brahman-sired cattle had heavier carcasses than Friesian-sired cattle by 9.8 kg or 4.2%. When the four carcass component weights (left hind-quarter, saleable meat, bone, trimmed fat) were each expressed as percentages of side weight, there were two that showed significant differences as a result of breed of sire: left hind-quarter percentage had an 0.7% greater value for Brahman-sired cattle (P < 0.001); and bone percentage was 1.5% less (P < 0.001) in Bralnnan-sired than in Friesian-sired cattle. Table 6 Least square means for the effects of breed of sire on each abattoir trait (adjusted for age at slaughter). Sire breed of calf Phenotypic ~ R e g r. Trait Brahman (B) Friesian (F) Diff.B-F SD on age (per d) Full weight pre-slaughter (kg) NS * Empty liveweight (kg) NS * Hot-carcass weight (kg) ** * Dressing-out percentage *** t Average fat depth (mm) NS t Eye muscle area (cm 2 ) *** ** Left hind-quarter (LHQ) wt (kg) ** * LHQ weight, % of side weight *** 0.89 O.Ollt Component weight of left side Saleable meat weight (kg) *** * Bone weight (kg) NS NS T r i mfat mweight e ~ (kg * t Weight 'as % ofleft side Saleable meat,,"-, NS 2.6 -O.004NS Bone *** 1.4 -O.016t Trimmed fat t NS NS = not significant; * = p < 0.05; ** = p < 0.01; *** = P < 0.001; t = P < 0.10.

8 Morris et al.-brahman and Friesian breeds as sires for beef production 283 Table 7 Least square means for the effects of breed of sire on six carcass traits (adjusted for hotcarcass weight, HeW). Sire breed of calf Phenotypic Regr. on Trait Brahman (B) Friesian (F) Diff. B-F SD Hew (per kg) Average fat depth (mm) NS *** Eye muscle area (cm 2 ) *** *** Left hind-quarter weight (kg) ** *** Component weight of left side Saleable meat weight (kg) * *** Bone weight (kg) *** *** Trimmed fat weight (kg) NS *** NS = not significant; * = P < 0.05; ** = P < 0.01; *** = P < Table 7 shows the corresponding breed-of-sire contrasts for fat depth, eye muscle area, and the four carcass component weights, with adjustment for hotcarcass weight. Average fat depth showed no effect of breed of sire in either analysis. In contrast to the same traits in Table 6, trimmed fat weight in Table 7 did not differ between breeds of sire; bone weight was still significantly less in Brahman-sired cattle; the other three traits (eye muscle area, left hindquarter weight, and saleable meat weight) were already superior in Brahman-sired cattle on an ageadjusted basis (Table 6) and the advantage was still present on a weight-adjusted basis (Table 7). Regression coefficients of components on hotcarcass weight showed that trimmed fat weight in the left side increased by kg (0.82%), fat depth increased by mm (0.98%), eye muscle area increased by cm 2 (0.20%), and saleable meat weight increased by kg (0.36%) for each 1 kg (0.42%) increase in hot-carcass weight. Thus, over the range of carcass weights analysed, fat was being deposited relatively faster than the increases in eye muscle area or meat weight. Table 8 presents the comparisons of export grades according to breed of sire. For carcasses from steers, there were no significant differences in percentages falling into the three categories shown. For carcasses from females, however, there was a significant difference in distribution as a result of breed of sire (P < 0.01), with more Friesian-sired carcasses falling into the lean group compared with the Brahmansired carcasses. Closer inspection of the data showed that, for heifers born in 1985 and 1986, a higher proportion of animals conceiving as yearlings fell into the M and L classes than into the K, T, and G classes. Because of the reproductive differences (Table 5), this included more Friesian-sired than TableS Numbers of carcasses classified by export grade, sex (F = female; M = male), and breed of sire. Breed of M and La P K,G, andt Sex sire (0--3 mm) (4--7 mm) (>7 mm) Total F Brahman 6 (17)b 20 (56) 10 (28) 36 Friesian 19 (44) 19 (44) 5 (12) 43 Total 25 (32) 39 (49) 15 (19) 79 M Brahman 11 (30) 24 (65) 2 (5) 37 Friesian 21 (36) 34 (58) 4 (7) 59 Total 32 (33) 58 (60) 6 (6) 96 a Export grades (M, L, P, K, G, and T) are explained in the text. b Percentages of each row total are shown in brackets. Brahman-sired animals. In contrast to the data on export grades, however, the fat depth and trimmed fat weight data at fixed carcass weight (Table 7) were effectively adjusted for physiological status of female, and they showed no significant difference in fat depth or fat weight as a result of breed of sire. Overall, it was concluded that fat deposition was affected by physiological status (Tables 5 and 8), carcass weight (Table 7), and sex of carcass (Table 8) but not by the Brahman versus Friesian breeds of sire. DISCUSSION General Six Brahman sires were used in this evaluation over three calf crops. These sires were the only ones available at Artificial Insemination Centres in New Zealand. Extensive enquiries in Australia at the time

9 284 New Zealand Journal of Agricultural Research, 1992, Vol. 35 showed that there were no others available there whose semen qualified on health-testing criteria for export to New Zealand. Any bulls available in New Zealand for natural mating would have been sired by the bulls whose semen was used in this experiment. It was considered that the interest by industry in Brahmans at the time, and the acceptable performance of Brahman crosses under temperate conditions (Cundiff et al. 1986), in addition to their documented advantages under tropical conditions (Frisch & Vercoe 1984),justified the study. Breeders involved in importations of any new strain of Brahman might need to consider the present results with caution however, because of sire numbers sampled here. Although not objectively recorded in this study, there was no doubt that the temperament of Brahman-sired calves was less suited than that of Friesian-sired calves to the traditional New Zealand rotational grazing and handling with stockman and dogs. Hearnshaw & Morris (1984) reported the same, using objective criteria for comparison of temperament in Grafton, New South Wales. Calf numbers, gestation length, date of birth, and liveweight traits Gestations initiated by Brahman sires were longer than those initiated by Friesian sires, and this was consistent with results (a 9.7-day difference) from these two breeds in the large Germ Plasm Evaluation (GPE) in America (Cundiff et al. 1986) and a 9.0- day difference in NSW (Barlow & O'Neill 1980). For birth weight, the same interaction of breed of sire x sex has also been reported before (Barlow & O'Neill 1980). For weights at birth, weaning, and 15-month stages, the GPE results showed that Brahman-sired calves were 3.9, 4, and 0 kg heavier than Friesian-sired calves respectively, and corresponding estimates in our study were 5.5, 4.2, and -9.0 kg. Values in the NSW experiment at birth and weaning were 2.1 and 3.1 kg respectively (Barlow & O'Neill 1980). Thus, overall, the two terminal sire breeds had different birth weights, but similar effects on liveweights from weaning to 15 months of age (relative to means at the different ages). Faecal egg counts One of the well-known advantages of Brahman-sired cattle over those sired by British breeds in tropical conditions is their lower FEC and internal parasite burden post-weaning (Frisch & Vercoe 1984). It was of interest to fmd silnilar results under our temperate New Zealand conditions; the FEC values from the Brahman-sired cattle were generally smaller. Barlow & Piper (1985) also found slightly lower FECs in Brahman-sired than Friesian-sired calves before weaning. Frisch & Vercoe (1984) found no difference as a result of breed of sire in FEC before weaning, but a significantly lower value for Brahman-sired animals than Hereford-sired animals from weaning up to 15 months of age (with a significant negative regression of FEC on weight gain over the period). However, unlike FEC data for the sheep species, FEC data in cattle are not as closely related to worm burdens (McKenna 1981). Covariate analyses in the present study showed no significant relationship between FEC and weight gain over the period when there was parasitism. In addition, there was no significant treatment effect on liveweight gain, as a result of drenching or withholding drench. This was in spite of grazing the two treatment groups together. Pregnancy data from heifers Our results were consistent with the GPE results (Cundiff et al. 1986) showing that fewer Brahmansired than Friesian-sired animals conceived as yearlings. Even under supplemented feed conditions in America, Cundiff et al. (1986) found an 88-day later age at puberty in Brahman-sired animals, giving them an average age of 429 days (14 months). Similarly in NSW, Hearnshaw etal. (1981) reported Brahman x Hereford means for age at puberty of 378 and 454 days at High and Medium nutrition levels, respectively, with Friesian x Herefords being respectively 62 and 49 days younger at puberty. With frrstjoining at 15 months of age in the High level and at 27 months of age in the Medium level, these authors observed first calving rates of 83 and 87% respectively for nutrition levels, and no difference as a result of breed of sire. Abattoir data Pre-slaughter weights in our experiment were consistent with the results from weaning to 18 months of age, showing no real difference as a result of breed of sire. In comparisons made in each of seven environments in southern Australia, Darnell et at (1987) found no significant difference in liveweight at slaughter between Brahman-sired and Friesian-sired cattle. The 4.2% advantage in hot-

10 Morris et al.-brahman and Friesian breeds as sires for beef production 285 carcass weight in Brahman-sired over Friesian-sired animals was not caused by differences in weights of fat depots carried by the Brahman-sired cattle (Table 7). Although not measured here, the difference probably resulted from relatively lower weights of lung, liver, and heart in Brahman-sired than Friesian-sired cattle, as shown in two separate experiments by Jenkins et al. (1981, 1986) for nondairy versus dairy breeds of cattle in the United States. In the GPE data (Cundiff et al. 1986), carcasses of Brahman-sired steers were 9 kg (3.1 %) heavier than those of Friesian-sired steers, in spite of a zero difference in pre-slaughter weight, which was consistent with our data. Similarly in NSW, Thompson & Barlow (1981) observed a 5.1% advantage in carcass weight to Brahman crosses over Friesian crosses at the same slaughter liveweight. The weight of retail product from one side was 1.5 kg (1.4%) greater from Brahman-sired carcasses in the GPE study, compared with a value of 3.5 kg (4.7%) in our study. At the high American carcass weights (297 kg average), there was a greater (+3.5 mm) fat depth in Brahman-sired carcasses than in Friesian-sired carcasses, whereas our comparison at 236 kg showed no effect of breed of sire on fat depth. In the NSW data (Thompson & Barlow 1981) with values adjusted to a fixed side weight of 125 kg, Brahman crosses had significantly lower bone weights, higher fat weights, and similar muscle weights to Friesian crosses. Although there were apparently significant effects of breed of dam on abattoir traits, the effects seemed inconsistent. The 175 carcasses were spread over 11 breeds of dam. Morris et al. (1987) reported a much larger study of effects of breed of dam using these same cows in an earlier experiment. CONCLUSIONS This study produced results for the two breeds of sire which were consistent with those under midwestern American and subtropical NSW conditions. In general, Brahman-sired animals were carried longer to term, were heavier at birth, but differed little in liveweight at later ages from Friesian-sired animals. They were more resistant to parasites, showed much later puberty, and thus poorer conception rates to yearling mating. They had heavier carcasses, and at fixed carcass weight they had lighter bone, more saleable meat, and a similar weight of trimmed fat. Results of comparing 11 breeds as terminal sires (Morris et al. 1990) showed that the Friesian halfbred carcasses were 5.7% heavier than the Hereford x Angus controls at 20 months of age. On the same scale, the Brahman would have been +10.2% and ranked about equal to the best of the sire breeds (the Charolais) at +9.0%. Whether or not Brahman-sired calves are desirable to New Zealand farmers would probably depend on other factors such as temperament, and on the versatility of the crossbred heifers. Friesian crosses are candidates for beef herd replacements or for slaughter, whereas Brahman crosses performed poorly under yearling mating conditions. ACKNOWLEDGMENTS We thank the International Brangus Breeders' Association (N. Z.) Inc. for the supply of semen from one Brahman bull; the Managers (E. G. Woods and B. D. Coe) and their staff at the Ruakura Experimental Abattoir for the collection of carcass and dissection data; Mr B. C. Hosking for assistance with the parasitological data; Ms S. F. Petch and staff for pepsinogen assays; and Miss J. M. Brown for assistance with data analysis. REFERENCES Agricultural Research Council 1965: Recommended procedures for use in the measurement of beef cattle and carcasses. Agricultural Research Council, London p. Baker, R. L.; Carter, A H.; Morris, C. A; Johnson, D. L. 1990: Evaluation of eleven cattle breeds for crossbred beef production: performance of progeny up to thirteen months of age. Animal production 50: Barlow, R.; O'Neill, G. H. 1980: Performance of Hereford and crossbred Hereford cattle in the subtropics of New South Wales: genetic analyses of preweaning performance of first-cross calves. Australian journal of agricultural research 31: Barlow, R.; Piper, L. R. 1985: Genetic analyses of nematode egg counts in Hereford and crossbred Hereford cattle in the subtropics of New South Wales. Livestock production science 12: Cundiff, L. V.; Gregory, K. E.; Koch, R. M.; Dickerson, G. E. 1986: Genetic diversity among cattle breeds and its use to increase beef production efficiency in a temperate environment. Proceedings of the 3rd World Congress on Genetics Applied to Livestock Production 9:

11 286 New Zealand Journal of Agricultural Research, 1992, Vol. 35 Darnell, R. E.; Hearnshaw, H.; Barlow, R. 1987: Growth and carcass characteristics of crossbred and straightbred Hereford steers. m. Post-weaning growth in seven environments in New South Wales. Australian journal of agricultural research 38: Everitt, G. C.; Jury, K. E. 1964: Implantation of oestrogenic hormones in beef cattle. IV. Effects of oestradiol benzoate plus progesterone on carcass composition and a comparison of methods of carcass evaluation. New Zealand journal of agricultural research 7: Everitt, G. C.; Jury, K. E.; Dalton, D. C.; Langridge, M. 1980: Beef production from the dairy herd. IV. Growth and carcass composition of straight-bred and beef-cross Friesian steers in several environments. New Zealand journal of agricultural research 23: Frisch, J. E.; Vercoe, J. E. 1984: An analysis of growth of different cattle genotypes rellied in different environments. Journal of agricultural science, Cambridge 103: Genstat 1988: Statistical Package: Genstat5, Release 1.3. Lawes Agricultural Trust (Rothamsted Experimental Station, U. K.). Hearnshaw, H.; Barlow, R.; Dicker, R. 1981: Age and weight at puberty and fertility in Hereford and first cross heifers. Proceedings of the Australian Association of Animal Breeding and Genetics 2: Hearnshaw, H.; Morris, C. A. 1984: Genetic and environmental effects on a temperament score in beef cattle. Australian journal of agricultural research 35: Jenkins, T. G.; Fetrell, C. L.; Cundiff, L. V. 1986: Relationship of components of the body among mature cows as related to size, lactation potential and possible effects on productivity. Animal production 43: Jenkins, T. G.; Long, C. R.; Cartwright, T. c.; Smith, G. C. 1981: Characterization of cattle of a fivebreed diallel. IV. Slaughter and carcass characters of serially slaughtered bulls. Journal of animal science 53: McKenna, P. B. 1981: The diagnosis of gastro-intestinal parasitism in cattle and sheep. Proceedings of the 11th Seminar of the Sheep and Beef Cattle Society of the New Zealand Veterinary Association: Morris, C. A.; Baker, R. L.; Carter, A. H.; Hickey, S. M. 1990: Evaluation of eleven cattle breeds for crossbred beef production: carcass data from males slaughtered at two ages. Animal production 50: Morris, C. A.; Baker, R. L.; Wilson, J. A.; Jones, K. R. 1987: Effects of eleven dam breed-types and six terminal sire breeds on beef carcass characteristics. New Zealand journal of agricultural research 30: Patterson, H. D.; Thompson, R. 1971: Recovery of interblock information when block sizes are unequal. Biometrika 58: Thompson, J. M.; Barlow, R. 1981: Growth and carcass characteristics of crossbred and straightbred Hereford steers. II. Carcass measurements and composition. Australian journal of agricultural research 32: Woods, E. G.; Fowke, P. J.; Bass, J. J.; Butler-Hogg, B. W. 1986: New Zealand beef export carcass grading. Proceedings of the New Zealand Society of Animal Production 46: