Pre-weaning Growth Rate Research Articles

The Influence of Dam Weight, Body Condition and Udder Scores on Calf Birth Weight and Preweaning Growth Rates in Beef Cattle

The Influence of Dam Weight, Body Condition and Udder Scores on Calf Birth Weight and Preweaning Growth Rates in Beef Cattle

Effects of Texel or Rouge de l’Ouest genes in lowland ewes and rams on ewe prolificacy, lamb viability and weaned lamb output

AbstractAn evaluation of the effects of the proportion of Texel or Rouge de l’Ouest (Rouge) genes in ewes (0, 0·5 or 1·0; the remainder being Greyface (Border Leicester × Scottish Blackface)) on prolificacy, lamb viability and lamb output was undertaken. A comparison of Texel and Rouge sires was carried out on Greyface, Texel and Rouge ewes. Prolificacy was higher in Greyface compared with Texel ewes (P = 0·06) but was lower in Greyface compared with Rouge ewes (P < 0·001). Prolificacy was similar in Greyface and Texel × Greyface ewes mated to Texel rams and in Greyface and Rouge × Greyface ewes mated to Rouge rams. The level of dystocia was similar in Greyface and Texel × Greyface ewes but significantly higher in Texel ewes (P < 0·001). The proportion of Rouge genes in the ewe had no effect on the level of dystocia. Litter weight of lambs at birth was significantly heavier in Greyface (P < 0·001) and Texel × Greyface (P < 0·01) ewes compared with Texel ewes. The proportion of Rouge genes in the ewe had no significant effect on litter weight. Lamb mortality (no. of lambs born dead and died birth to weaning) was significantly greater with Rouge ewes compared with the other ewe breed types (P < 0·001). The number of lambs which died from birth to weaning was lower with Texel × Greyface compared with Greyface ewes (P < 0·01). Expressed on a unit metabolic weight basis, Greyface ewes produced a significantly greater weight of lamb compared with Texel (P < 0·05) and Rouge ewes (P < 0·001). Texel × Greyface ewes produced a significantly greater weight of Texel-sired lamb compared with Greyface (P < 0·01) and Texel ewes (P < 0·001).Sire had a significant effect on a number of parameters. The number of productive ewes was significantly lower in ewes mated with Texel sires (P < 0·001). Lamb birth weights and pre-weaning growth rates were greater with Rouge sires (P < 0·05). Number of lambs weaned per ewe lambed was significantly greater with Texel sires (P < 0·01). Overall weight of weaned lamb produced per ewe was not significantly affected by sire breed.

Growth and sexual development of Etawah-cross kids from does of different levels of milk production

The experiment was conducted to evaluate growth and sexual development of female Etawah-cross kids of the progeny of the does with low (Group L), medium (Group M) and high (Group H) milk production. The does were fed King grass ( Pennisetum purpureophoides) (about 2% DM of liveweight) and 400 g/head of concentrate. The amount of concentrate was increased to 600 g/head during the last two months of pregnancy period and during lactation. Kids were weaned at four months of age. Thereafter, they were reared in group and were fed King grass and concentrate. The animals were weighed every two weeks. A mature vasectomized buck were joined in each group to detect the onset of first oestrus (puberty). When kids reached puberty and had a liveweight of about 20 kg, they were mated with intact buck. Ovulation rate, progesterone profiles and fertility were observed. The results showed that pre-weaning growth rates of kids in all three groups were not significantly different (67.0 vs 74.9 vs 70.5 g/day, P>0.05). At six and 12 months of ages, Groups L and M had almost the same liveweight which were higher than Group H. Consequently, Groups L and M reached puberty about 3 - 6 weeks earlier than Group H. The average liveweight at puberty was 19.9, 18.2 and 18.8 kg for Groups L, M and H, respectively, or at about 57.1-69.8% (average 63.2%) of mature liveweight. The pregnancy rate following first mating was relatively high (67-73%) and all does were pregnant in the following mating. Average ovulation rate at conception were low (1.1) in all groups. It was concluded that differences in milk production of the does did not significantly affect post-weaning growth and sexual development and performances of kids. Other factors at certain age or growth phases might be more important to affect growth and reproduction of Etawah-cross goat, and this may warrant further study. Key words : Growth, reproduction, Etawah-cross does

Effect of supplemental nutrients on the growth performance of sucking pigs

Twenty-seven sows were allocated at their first farrowing to 3 experimental treatments in which their sucking pigs had access to no supplemental milk, liquid cow milk (CM), or a synthetic milk supplement (SM). Liquid cow milk contained 128 g total solids/kg, 24·2 g CP/kg, 30·4 g fat/kg, and 1·8 g lysine/kg, whereas the supplemental synthetic milk contained 200 g total solids/kg, 102·6 g CP/kg, 36·0 g fat/kg, and 9·0 g lysine/kg. All litters contained 12 pigs and the supplemental milk products were offered ad libitum from Day 4 of lactation until weaning at 28 days of age. Between Days 0 and 14 of lactation, there was no effect of treatment on supplemental milk intake or average piglet growth rate but between Days 14 and 28 of lactation, litters given milk supplements grew faster than litters receiving no supplemental milk. Overall, piglet growth rates between Days 0 and 28 of lactation were greater for litters receiving supplemental milk (297 and 277 g/day for CM and SM litters, respectively) than for litters receiving no supplemental milk (239 g/day). Piglets offered cow milk drank more milk between Days 4 and 28 of lactation than piglets offered the synthetic milk (5·48 v. 2·38 kg/day). Piglets in litters which had access to cow milk visited the supplemental feeder more often (5·5 v. 2·7 visits per suckling interval) and spent longer at the feeder (45·4 v. 14·5 s) than pigs in litters which had access to the synthetic milk supplement. Average sow milk production was 15·4 and 15·3 kg/day between Days 11 and 14 and between Days 25 and 28 of lactation, respectively, and was unaffected by treatment. Treatment also had no significant effect on average suckling interval on Day 21 of lactation (51·7 min) or carcass composition of representative pigs from each litter killed at 28 days of age. Between Days 14 and 28, female pigs grew faster than male pigs (304·3±9·3 v. 292·0±9· 2 g/day). These results demonstrate that provision of supplemental milk to sucking pigs can improve preweaning growth rate and the response increased as lactation proceeded.

Note on age and body weight at puberty in Mehraban Iranian fat-tailed ewe lambs.

Data on 436 Mehraban fat-tailed ewe lambs collected during 1985 to 1988 were analysed. A 4-year study of factors affecting age and body weight at puberty in Mehraban ewe lambs showed that the year of birth did not affect age at puberty but body weight at puberty. Sires significantly influenced age and body weight at puberty with body weight being more important than age. Sire-group correlation of age at puberty between years was low while that of body weight was relatively high. Date of birth within the year had a significant effect on age and body weight at puberty. Ewe lambs born late in the lambing season were lighter and younger at puberty. High pre-weaning growth rate and heavy weaning weight were associated with early puberty and heavy body weight at puberty. Age and body weight at puberty averaged 244.7 (s.d. 13.9) days and 44.1 (s.d. 2.4) kg respectively. Heritability estimates for age and body weight at puberty were 0.14 and 0.37 respectively.

Responses in gilt post-farrowing traits and pre-weaning piglet growth to divergent selection for components of efficient lean growth rate

AbstractResponses in gilt live weight, backfat depth and food intake during lactation and in pre-weaning piglet growth rate were examined after seven generations of divergent selection for daily food intake (DFI), lean food conversion (LFC) or lean growth rate (LGA) on ad-libitum feeding or lean growth on restricted feeding (LGS). There were 252 Large White gilts in the study. Selection for low DFI resulted in gilts with less backfat (25·7 v. 30·7 (s.e.d. 2·21) mm) at farrowing and a substantially lowerfood intake (129 v. 146 (s.e.d. 5) kg) during lactation, but similar reductions in live weight (42 (s.e.d. 6) kg) and backfat depth (8·4 (s.e.d. 1·7) mm) than with selection for high DFI. Therefore, the lower piglet growth (167 v. 295 (s.e.d. 11) g/day) with selection for low DFI compared with selection for high DFI was primarily due to lower food intake of the gilts, as energy for milk production from food was reduced. In contrast, selection for high LFC resulted in relatively smaller changes in live weight (37 v. 48 (s.e.d. 5) kg) and backfat depth (7·6 v. 8·9 (s.e.d. 1·3) mm) than selection for low LFC, which combined with a lower food intake (132 v. 148 (s.e.d. 4) kg) during lactation, resulted in lower piglet growth (181 v. 200 (s.e.d. 11) g/day). The higher food intake of high LGA gilts (137 v. 121 (s.e.d. 4) kg) compensated for the relatively lower reductions in live weight (41 v. 46 (s.e.d. 5) kg) and backfat depth (5·5 v. 6·7 (s.e.d. 1·3) mm) during lactation compared with the low LGA line, such that piglet growth was similar (195 v. 289 (s.e.d. 11) g/day) in the two selection lines. In the high and low LGS selection lines, piglet growth was similar (195 v. 186 (s.e.d. 11) g/day) as was gilt food intake (125 v. 227 (s.e.d. 5) kg) and the changes in live weight (39 v. 41 (s.e.d. 6) kg) and backfat depth (8·1 v. 7·7 (s.e.d. 2·2) mm) during lactation. An examination of the daily energy used in litter gain and the energy available from gilt food intake and mobilization of body lipid indicated that one equation to predict the amount of body lipid mobilized during lactation was not appropriate for different genotypes. Responses in gilt food intake and the changes in live weight and backfat during lactation were selection strategy dependent. However, in general, the selection strategies which reduced gilt voluntary food intake during lactation or resulted in lower live weight and backfat depth at farrowing were detrimental to piglet growth rate.

Plasma IGFI and BW correlate independently with preweaning growth rate in lambs

Plasma IGFI and BW correlate independently with preweaning growth rate in lambs

Feeding dairy ewes and goats and growing lambs and kids mixtures of protein supplements

In two trials, with 86 lactating Chios ewes and with 66 Damascus goats, the effect of protein source (soybean (SB) or mixture of SB and meat meal (MM)) on pre- and post-weaning lactation performance and the pre-weaning growth rate of their offspring was studied. In another three trials with early weaned Damascus kids (50 ± 3 days of age) and Chios lambs (42 ± 3 days of age) the effect of level of inclusion of soybean meal (SB) and of partial replacement of SB with either fish meal (FM) or MM on their performance was studied. The diets in Trial 1 with a total of 81 kids were SBH (high level of SB), SBL (low level of SB) and FM (partial replacement of the low level SB with fish meal); the diets in Trials 2 (112 Damascus kids) and 3 (165 Chios lambs) were SBH (high level of SB), SBL (low level of SB), MMH (partial replacement of high level SB with MM) and MML (partial replacement of low level SB with MM). Total milk yield, milk suckled, milk sold, BW changes of ewes and goats on the two diets and growth rate of their offspring until weaning did not differ between supplements ( P > 0.1). During the post-weaning period, there were no differences ( P > 0.1) between diets in either milk yield or milk composition. Kids fed the SBH diet grew faster ( P < 0.02) than those fed the SBL diet (Trial 1). In contrast, there were no differences between SBH and FM and/or SBL and FM diets. Kids fed the MMH (Trial 2) diet gained more BW ( P < 0.012) than those on the SBH and SBL diets; there were no differences between MMH and MML diets and/or among diets MML, SBH and SBL. In Trial 3 with lambs, no differences were noted among diets ( P > 0.1). In all three trials, males were heavier than females at the commencement and at the end of the trial. We conclude that partial replacement of SB by MM will not increase milk yield of ewes and goats. However, meat and soybean meals can replace each other. With regard to fattening offspring it is concluded that (1) MM and FM can successfully replace SB, (2) their inclusion may improve animal performance and (3) combination of SB with either MM or FM will result in satisfactory growth even at lower levels of dietary CP. The selection among the protein supplements used can be made on the basis of cost per unit of protein.

Estimates of environmental and genetic parameters influencing milk and growth traits of Awassi sheep in Cyprus

Data on 1213 ewes and 1382 lambs of both sexes, born between 1978 and 1991 at the Orites Livestock Unit, were used in a study of environmental and genetic factors affecting ewe productivity and lamb growth in the Awassi breed. Genetic and phenotypic parameters were estimated for some production and reproductive traits in ewes and for growth traits in lambs. Year and season of lambing significantly affected all production and reproductive traits in ewes and growth traits in lambs. Lamb birth weight was not affected by season of lambing. Parity (lactation number) had a significant quadratic effect on all ewe and lamb traits except postweaning lamb growth rate, which is probably free from maternal effects. Type of birth and sex were the most important sources of variation in lamb growth with the exception of postweaning daily gain, which was not influenced by type of birth. Estimated heritabilities for ewe production and reproductive characters were modest, but most were high enough to justify selection procedures for their improvement. In particular, the estimates for prolificacy (0.30 ± 0.08) and part (0.58 ± 0.12) or total (0.56 ± 0.11) lactation milk yield indicated that both traits can be improved and particularly prolificacy, which is one of the weaknesses of the breed. The results of the present study indicate that postweaning growth rate is probably the best criterion of selection to improve lamb performance. This criterion, or the 105-day weight, should be superior to weaning weight or preweaning growth rate since they are probably much less influenced by maternal effects that mask the genetic potential of the lamb for fast growth. The absence of genetic antagonisms among ewe or lamb traits indicated that correlated responses in other traits from selection on milk production or postweaning growth would not be negative.

Responses in gilt post-farrowing traits and pre-weaning piglet growth to divergent selection for components of efficient lean growth rate

Responses in sow traits at farrowing and during lactation and in pre-weaning piglet growth rate were determined in a population of Large White pigs, after seven generations of divergent selection for components of efficient lean growth rate. Information on the factors influencing preweaning piglet growth rate is required for a comprehensive evaluation of alternative selection strategies.There were four selection groups: daily food intake (DFI), lean food conversion (LFC), lean growth rate (LGA) on ad-libitum feeding and lean growth rate on scale feeding (LGS). There were 242 gilts in the study, with 20 gilts in the high, low and control lines of each selection group. Pigs in the ad-libitum selection groups were performance tested over a fixed weight range of 30 to 85 kg. Pigs fed on scale feeding were performance tested for a fixed time period of 84 days from 30 kg with food intake equal to 0.75 g/g of daily ad-libitum food intake. Matings were unsupervised and took place in outside paddocks.

Responses in gilt post-farrowing traits and pre-weaning piglet growth to divergent selection for components of efficient lean growth rate

Responses in sow traits at farrowing and during lactation and in pre-weaning piglet growth rate were determined in a population of Large White pigs, after seven generations of divergent selection for components of efficient lean growth rate. Information on the factors influencing preweaning piglet growth rate is required for a comprehensive evaluation of alternative selection strategies.There were four selection groups: daily food intake (DFI), lean food conversion (LFC), lean growth rate (LGA) on ad-libitum feeding and lean growth rate on scale feeding (LGS). There were 242 gilts in the study, with 20 gilts in the high, low and control lines of each selection group. Pigs in the ad-libitum selection groups were performance tested over a fixed weight range of 30 to 85 kg. Pigs fed on scale feeding were performance tested for a fixed time period of 84 days from 30 kg with food intake equal to 0.75 g/g of daily ad-libitum food intake. Matings were unsupervised and took place in outside paddocks.

Utilization of FecJ F gene in developing commercial sheep farming : Economic analysis

An increase of income per capita in Indonesia is not followed by an increase of numbers and quality of lambs stock. To meet he high demand both for domestic and international markets, sheep production should be elaborated commercially . The Research Institute for Animal Production, Bogor has been able to identify the segregation of FecJ F on Javanese sheep, which has large effect on ovulation rate and number of litters born. The study was purposed to analyse the economic value of using Fed gene and the crossing with St. Croix rams to obtain high number of lamb production as well as high pre-weaning growth rate . Sixty seven Garut ewes were used and classified into three classes of singles, twins and triplets or mom: lambs born . From each litter type, ewes were classified according to the breed of rams to be used . Gamt and St . Croix rams were used to represent small and large size of sires, respectively . The parameters observed were litter size, birth weight, sex, feed consumption, weaning weight and average daily gain . Lambs and ewes were weighed on biweekly and monthly basis, respectively. An increasing of input for single born ewes was not followed by dramatic increase in its body weight at weaning, which means that the optimum level of production was not achieved. This resulted a shortening of farmers income. However, for ewes having twins an increase of input was followed by significantly increased of production level . Therefore, the economic analysis model used for ewes that carry the Fed gene showed an increase of income of Rp.30,691 .50, and Rp.24,319.82, per ewe per period for St. Croix sires and Garut sires, respectively . Key words: Economic analysis, Fed gene, sheep

Estimates of genetic parameters for mature weight of Australian beef cows and its relationship to early growth and skeletal measures

Estimates of genetic parameters were obtained for mature weight and the two parameters of a Gompertz growth curve, namely average mature weight and rate of maturing, fitted for each animal for a herd of Polled Hereford cows and a herd of multi-breed synthetic cows, so-called Wokalups. Both herds were part of a selection experiment for preweaning growth rate conducted in Western Australia. In addition, cannon bone length, measured at birth, and hip height, recorded at weaning, and their association with birth, weaning and final weights were examined. Wokalups consistently exhibited more phenotypic and genetic variability than Herefords with higher heritabiliy estimates for all traits. Heritabilities for average mature weight were 0.47 for Herefords and 0.73 for Wokalups compared to values of 0.29 and 0.54, respectively, for mature weights treated as repeated records. Rate of maturing was moderately heritable in both breeds, heritability estimates being 0.32 and 0.33. Genetic correlations between cannon bone length and mature size were 0.6 to 0.7 and between cannon bone length and rate of maturing were −0.5 to −0.6. There was an adverse genetic correlation, −0.5 for Herefords and −0.7 for Wokalups, between rate of maturing and mature weight, i.e., earlier maturing animals tended to have shorter cannon bones and lower mature weights. Scope for a genetic evaluation for mature size, including cannon bone length as an indicator trait, is discussed.

Effects of PCBs (Aroclor 1254) on reproduction and growth rate in mongolian gerbils ( [formula omitted

Groups of female Mongolian gerbils were subcutaneously administered 2mg or 4mg PCBs (Aroclor 1254) in 0.1ml oil or vehicle only after pairing for two days with untreated males. No effects were found on the number of pairs breeding, birth intervals, number of pups per litter or percentage of male offspring. The preweaning growth rates of the PCBs exposed first litter offspring was retarded, but second litters showed no differences compared to controls. No other differences in growth were observed.

Effect of dam nutrition and suckling on lactation in Borana cows and growth in their Borana × Friesian crossbred calves in an early weaning system in Ethiopia

AbstractForty-four Borana × Friesian F1 crossbred calves born to Borana (Bos indicus) cows were randomly assigned to either suck their dams hvice daily or bucket-feeding with 1341 milk over a 57-day pre-weaning period. Their dams were also allocated either to a supplement group with grass hayad libitumand 5 kg per head per day of a concentrate ration or to an unsupplemented group withad libitumgrass hay only. Calves were fed in individual boxes in a calf house. The mean birth weight of calves was 24·8 (s.e. 1·8) kg. Suckled calves were heavier (P &lt; 0·01) at weaning (47·7 (s.e. 1·9) v.37·1 (s.e. 1·8) kg) and had faster pre-weaning growth rate (411 (s.e. 30)v.215 (s.e. 29) g/day) than bucket-fed calves. Calves which sucked supplemented cows were heavier (P &lt; 0·001) at weaning (51·2 (s.e. 2·6)v. 44·2 (s.e. 2·6) kg), had faster (P &lt; 0·01) pre-weaning growth rate (477 (s.e. 41)v.346 (s.e. 41) glday) and higher (P&lt;0·01) daily milk intake (2·6 (s.e. 0·2)v.1·6 (s.e. 0·2) I/day) than those which sucked unsupplemented cows. Mean concentrate intake was 302 (s.e. 30) g/day for bucket-fed calves and 341 (s.e. 33) and 408 (s.e. 33) g/day for calves which sucked supplemented and unsupplemented cows. Cow milk production was higher (P &lt; 0·01) in suckled than in milked cows (3·3 (s.e. 0·2)v.1·0 (s.e. 0·2) I/day) and in supplemented than unsupplemented cows (3·9 (s.e. 0·2)v.2·7 (s.e. 0·2) I/day). Concentrations of milk protein, fat and total solids averaged 39 (s.e. 15), 49 (s.e. 16) and 143 (s.e. 21) g/kg, respectively and were not significantly influenced by either concentrate supplementation or suckling. Restricted suckling and early weaning coupled with appropriate calf and cow feeding regimes could be one of the alternatives for calf rearing under smallholder and small scale peri-urban dairy production systems. However, further studies are warranted to evaluate the effects of such a strategy on both calf and cow performances under these production systems.

Genetic parameters for growth traits of Australian beef cattle from a multibreed selection experiment.

Estimates of covariance components and genetic parameters were obtained for birth, weaning, 200-d, and 400-d weight for a herd of Polled Herefords and a herd of a multibreed synthetics, the so-called Wokalups. Data originated from an experiment in Western Australia selecting for preweaning growth rate. Analyses were carried out by REML fitting an animal model including genetic and permanent environmental maternal effects. Wokalups showed consistently more phenotypic variation, partly due to a scale effect, and higher direct and lower maternal heritabilities than Herefords. Maternal environmental effects were more than twice as important in Herefords than in Wokalups. Estimates of both genetic and environmental correlations among weaning and subsequent weights were essentially unity, identifying maternal effects found for postweaning weights as a "carry over" of those on weaning weight.

Cryopreservation of embryos as a means of germ plasm conservation in sheep

Embryos were collected from 4 lines of Targhee sheep between 1986 and 1990. The lines were selected for preweaning growth rate (Lines DH and HW) or for multiple births (Line HT); Line C served as an unselected control group. Estrus was synchronized using fluorogestone acetate-impregnated vaginal pessaries, and ewes were superovulated with FSH. Embryos at the morula or blastocyst stage were surgically recovered from mature ewes at Days 5 to 6 and were frozen following morphological evaluation. The overall average number of freezable embryos per collection was 2.9, and did not differ significantly among years or among lines. Of the embryos collected between 1986 and 1988, 92 were transferred to 53 recipients in 1989, producing 53 lambs. Survival rates were 60.9 and 47.8%, respectively, for embryos evaluated as good and fair after thawing. Good-quality blastocysts yielded the highest survival rate (64.4%). Analyses indicated no significant effects of line, developmental stage or embryo evaluation on the incidence of lambing. It was concluded that embryos of morula or blastocyst stage can be successfully frozen for extended periods. The data on embryo yield and survival following cryopreservation were used to calculate numbers of donors needed to preserve and reconstitute a population of specified size.

The performance of Brahman-Shorthorn and Sahiwal-Shorthorn beef cattle in the dry tropics of northern Queensland. 3. Birth weights and growth to weaning

The birth weights and weaning weights of Bos indicus cross calves from 4 inter se mated herd groups in a dry tropical environment were studied. The calving season commenced in late October, about 2 weeks before the start of the pasture-growing season. Second and subsequent generations of 1/2 Brahman and 1/2 Sahiwal crosses and first backcross, and later generations of 3/4 Brahman and 3/4 Sahiwal crosses, were represented. The Bos taurus component of the crosses was primarily Beef Shorthorn. In general, Brahman crosses were heavier at birth and grew faster to weaning than Sahiwal crosses (P&lt;0.05), with consequent advantages in weaning weights of 11 and 6 kg in first backcross and late generation crosses, respectively. There was a birth weight advantage (P&lt;0.05) of 1/2 crosses over 3/4 crosses, which was eroded by the time of weaning. Superior growth rates of 3/4 crosses were primarily expressed in years with greater nutritional stress and appeared to be due to better adaptation to environmental stresses by the calf. The only difference between filial generations was the growth rate advantage (P&lt;0.05) of F2 1/2 crosses over F3 1/2 crosses, apparently due to suckling of F1 and F2 dams, respectively. Males exhibited an 8% average advantage (P&lt;0.05) over females for all weight and growth traits in late generation calves. Calves with mature dams were 1.8 kg heavier (P&lt;0.05) at birth. This, along with their higher (P&lt;0.05) preweaning growth rate (19-49 g/day), resulted in calves with mature dams being 4-10 kg heavier (P&lt;0.05) at weaning than calves of young cows. Differences between years in birth weights and preweaning growth rates were &lt;25% (P&lt;0.05). Birth weight was affected by nutrition of the dam in late pregnancy (early calves were generally about 1 kg lighter than late calves), and growth of calves was higher in years when the pasture growing season commenced earlier.

The effects of oestradiol treatment on activity, growth and survival in neonatal piglets

AbstractTwo experiments were conducted to elucidate the effects of intra-muscular injection of oestradiol within 1 min of birth (experiment 1) or within 4h of birth (experiment 2) on piglet activity, growth and pre-weaning survival rate. In experiment 1, 248 piglets (25 litters) were alternately injected within litter at birth with either 1 ml peanut oil/saline solution or 0·1 mg oestradiol benzoate in this carrier solution. The subsequent behaviour, growth and survival of these piglets were recorded. Experiment 2 used 38 litters (385 piglets), these being treated by litter with either of the same two treatments as soon after birth as they were found (approx. range 0 to 4 h). Piglet survival data were collected from this field trial. Oestradiol treatment significantly reduced the intervals from birth to reaching the udder (596 v. 740 s, P &lt; 0·05) and from birth to first sucking (1060 v. 1497 s, P &lt; 0·01) relative to control piglets in experiment 1. Treatment had no significant effect on pre-weaning growth rate (experiment 1), but did tend to reduce early postnatal mortality rate in both experiment 1 (7·2 v. 2·4% for control and oestradiol-treated piglets respectively) and experiment 2 (13·0 v. 10·2% for control and oestradiol-treated piglets respectively). It is concluded that oestradiol treatment at, or soon after, birth induces short-term hyperactivity in piglets. This may subsequently be reflected in an improvement in pre-weaning survival rate of piglets, although further data are required to confirm this conclusion.

Comparison of crossbred cows containing various proportions of Brahman in spring or fall calving systems: III. Productivity as three-, four-, and five-year olds

Productivity of 3-, 4-, and 5-yr-old crossbred cows containing various proportions (0, 1/4, or 1/2) of Brahman breeding out of Angus or Hereford dams was evaluated using 489 spring-calving and 427 fall-calving records collected over a 4-yr period. Cows were bred to Limousin sires for the first 3 yr and to Limousin and Salers sires the 4th yr. Interactions between crossbred cow group and season of calving were not significant. Percentage of cows exposed to breeding that weaned a calf increased (P less than .01) as proportion Brahman breeding increased, was higher (P less than .01) for cows out of Angus dams than for cows out of Hereford dams, and was higher (P less than .01) for spring-calving cows. As the proportion Brahman increased, the percentage requiring assistance at birth decreased, and cows out of Angus dams required less (P less than .05) assistance than those out of Hereford dams. Preweaning ADG, adjusted weaning weight, weaning conformation, weaning condition, and adjusted weaning hip height increased a proportion Brahman breeding increased. Spring-born calves gained .12 kg/d faster (P less than .01) than fall-born calves. However, weight at weaning was similar for the two groups; spring-born calves were weaned at an average age of 205 d, and fall-born calves were weaned at an average age of 240 d. Fall-calving cows were heavier (P less than .05) than spring-calving cows, and 0 and 1/2 Brahman cows were heavier (P less than .01) than 1/4 Brahman cows. These data indicate that Brahman-cross dams can be used to improve reproductive rate and increase preweaning growth rate, and thus weaning weight.(ABSTRACT TRUNCATED AT 250 WORDS)