Growth Rate Of Calves Research Articles

Influence of partial suckling of crossbred dairy cows on milk offtake and calf growth in the Ethiopian highlands

The effects of implementing a restricted suckling regime with crossbred dairy cows have been examined in the Ethiopian highlands. Calves were allowed to suckle their dams for two minutes before each milking until weaning and this system was compared with the common practice of rearing by bucket feeding. Restricted suckling significantly increased calf growth rate to weaning, from 0.31 to 0.53 kg/d (P less than 0.01). No differences in calf growth post-weaning occurred, so that the 20 kg difference in liveweight that had been achieved by the restricted suckled calves by the time of weaning persisted until the calves were nine months old, when observations ceased. Total milk offtake was not significantly affected by treatment, although that obtained from the partially-suckled animals over their whole lactation exceeded that from the other treatment by 15%. Partial suckling delayed return to oestrus post partum but this was offset to some degree by fewer services per conception, hence calving interval was not significantly increased. Voluntary feed consumption was similarly unaffected and it is concluded that restricted suckling offers tangible advantages for adoption by smallholders using crossbred cows in dairy production systems.

Efficacy of chemical castration and effects of age at castration and implant regime on growth rate, testicular measurements and testosterone levels of beef calves

In 1984–1985 and 1985–1986, groups of 136 and 127 male calves were used to assess the effects of multiple implants (Ralgro or Steeroid), castration time (early or late) and castration method (surgical or chemical) on testicular development and weight gain for 28 d following castration. Ralgro-implanted bull calves had smaller scrotal circumference (P < 0.001) and testicle weight (P < 0.001) than nonimplanted calves at early castration (59 ± 1 d), late castration (157 ± 1 d) and at slaughter (459 ± 3 d). Steeroid had no effect on testicle weight at early castration (40 ± 1 d) but reduced testicle weight (P < 0.001) at late castration (148 ± 1 d). Average daily gain (ADG) during the first 7 d postcastration was less for surgically castrated than chemically castrated calves or bulls following early castration (P < 0.05) but in the 7 d following late castration, bull calves grew faster than surgical castrates (P < 0.05) and surgical castrates grew faster than chemical castrates (P < 0.05). The ADG of calves implanted with Ralgro was greater than that of nonimplanted calves during the 28-d period following early and late castration (P < 0.05) but Steeroid had no effect (P > 0.05) on 28-d postcastration ADG. Chemical castration increased scrotal circumference at 7, 14 and 28 d postcastration (P < 0.001) but by day 56, testicular atrophy was complete in those calves that were successfully castrated. Chem-cast was an effective method of castration in young calves (< 90 kg liveweight), particularly those that had been implanted with Ralgro, but efficacy was reduced (P < 0.05) in older calves (> 150 kg liveweight). Key words: Castration, Chem-cast, Ralgro, Steeroid, testosterone, beef

Growth and subsequent fertility of cows implanted during pregnancy with trenbolone acetate and oestradiol

Under extensive grazing conditions in Australia the pregnancy status of cows is often not known. It is therefore conceivable that if anabolic steroids are administered to females, some may be pregnant. This experiment examined the consequences of such an action. Sixty-nine multiparous cows were grazed together from the sixth to eighth month of pregnancy in July until calf weaning the following May. Thirty-five were implanted in the ear with Revalor� (200 mg trenbolone acetate and 20 mg oestradiol-17G) only once at the commencement of the experiment in July. The remainder served as controls. Treated cows had significantly (P < 0.01) higher liveweight gains pre-calving (0.39 v. 0.28 kg/day) and significantly (P < 0.05) lighter calves at birth (32 v. 35 kg) than the controls. There was no effect of treatment on calf survival before or after birth, calf growth rate or cow fertility after calving.

MILK YIELD AND COMPOSITION IN BEEF COWS AND THEIR EFFECT ON COW AND CALF PERFORMANCE IN TWO ENVIRONMENTS

Relationships of milk yield and composition of 10 specific F1 crosses of beef cows with preweaning growth of their calves and with changes in the weight and subcutaneous fatness of the cows during lactation were examined over 2 yr for a population of 120 cow-calf pairs each year at two climatically distinct locations. The crosses were represented by the Hereford × Angus (HA) and nine crosses produced by mating Charolais (C), Simmental (S), and Limousin (L) sires to cows of Hereford (H), Angus (A), and Shorthorn (N) breeding. Environmental differences were provided by two climatically distinct locations (Brandon, Manitoba; Manyberries, Alberta) with two treatments (drylot confinement, T1; pasture, T2) imposed at each location. Milk was measured at 8-wk intervals commencing 1 June and terminating 1 October (weaning). Cow weight and fat at calving were positively associated (P < 0.0001) at both locations. Weight of the cow at calving was positively associated with average milk yield and calf growth rate at Manyberries (P < 0.0001), but at Brandon the association was positive but not significant (P > 0.05). Weight of cow at calving was positively associated with calf birth weight at Manyberries (P < 0.02). Calf preweaning growth rate was directly related to birth weight (P < 0.009). Calf sex had the expected effect on calf growth rate throughout lactation (M > F) but milk yield of the cow was not influenced by the sex of calf reared. Percentages of the milk constituents (butterfat (BF), solids-not-fat (SNF), protein (PT), declined as milk yield increased but the reduction was significant only for PT (P < 0.0005). Changes in cow weight and subcutaneous fat cover during lactation were inversely related with milk yield, the reductions in weight being significant (P < 0.008) at both locations and the loss of subcutaneous fat cover significant (P < 0.0001) only at Manyberries. Calf growth rate increased as milk yield increased with the largest regression coefficients at each stage of lactation provided by the estimate of average milk production for the complete lactation; however, this difference was not significant (P > 0.05). The statistical model with the covariate average milk production accounted for approximately 58% of the variance for calf gain during the lactation period. The covariate alone contributed 36% of this total R2 value at Brandon and 48% at Manyberries. Simmental cross cows produced the fastest growing calves while HA and L cross cows produced the slowest growing calves at both locations. The highest milk yields were recorded for the S cross cows at both locations while HA cows were lowest at Brandon and LH the lowest at Manyberries. At both locations, the SN cows recorded the lowest values for % BF and % SNF, and the SA cows recorded the highest values for % PT. For % BF and % SNF, the HA cows were the highest at Brandon while at Manyberries, the LH cows recorded the highest values. Average milk yield (AMY) was the best milk production variable explaining variance associated with calf growth. The R2 values were higher at Manyberries than Brandon and the R2 values decreased as the lactation season progressed. The addition of any of the milk constituent variables added little to the R2 values for AMY. Key words: Milk yield, milk composition, calf growth, cow weight change, cow subcutaneous fat change

Biological and economic impact of trypanosome infections on milk production in N'Dama cattle managed under village conditions in The Gambia

ABSTRACTOver a 3-year period, productivity characteristics and criteria of trypanosomiasis incidence and severity have been monitored by monthly examination of individual N'Dama cattle in villages in The Gambia. From this database, 60 lactating cows in which Trypanosoma congolense or T. vivax had been detected on blood examination (group 1) were compared with 50 cows which had not been found infected with trypanosomes during the monitoring period (group 2). The latter were selected on the basis of comparability of age and stage of lactation to those of group 1 for examining the effect of trypanosome infections on the quantity of milk extracted for human consumption, and on the growth of their sucking calves. Data from a 6- to 7-month period were examined in the analysis.The quantity of daily milk extracted during the 1st month ot intection (group 1) decreased by proportionately 0·25 in comparison to the amount extracted during the preceding month when parasites were not detected. The corresponding figure in the uninfected controls (group 2) was 0·02. The mean daily milk extracted for human consumption from uninfected cows during a 6-month period was proportionately 0·26 higher than the mean for the infected cows. Growth rates of calves sucking infected and uninfected dams were similar.These observations indicate that infection with pathogenic trypanosomes of lactating N'Dama cattle causes a reduction in milk production.In economic terms, it was estimated that the decline in milk extracted for human consumption due to trypanosome infections amounted to an average of £1 per month per cow.

A comparison of the growth rate of single and twin born beef calves

It is frequently hypothesised that Increasing the litter size of the beef cow would increase output and biological efficiency. Such hypothesis is supported by the simulation study of Guerra-Martlnez et al (1987), which Indicated that twinning would Increase biological and economic efficiency of beef production by 20 to 25%. However, there is little published data on the comparative growth rates of single-born, single-reared and twin-born and twin-reared beef calves. The objective of the present study was to determine the effect of birth type (single or twin) on growth rate from birth through to beef and on final carcase weight, carcase conformation and fatness level.

The effect of supplemental yeast culture (yea-sacc) on patterns of rumen fermentation and growth performance of intensively fed bulls

Supplementation with Yea-sacc - yeast (Saccharomyces cerivisiae ‘1026’) and its growth medium - has been found by several workers to alter rumen fermentation patterns, increase milk yield and growth rate in dairy cows and calves. This experiment investigated the effect of inclusion in the diet of intensively fed bulls on rumen fermentation and animal performance.Twenty-six Limousin x Friesian bulls reared to 3 months of age on a common diet were allocated to treatment on the basis of liveweight and previous growth rate at an average liveweight of 133 kg.The Treatments were Control ‘C” and Yea-sacc ‘YC’ - the control diet supplemented with Yea-sacc. (Alltech Inc. USA) at 1.5 kg/tonne of fresh feed. The diet was a mixture of barley and soyabean meal (Tables 1 & 2) with the inclusions of the latter reduced at 159 days. Mineral and vitamin supplements were included together with molasses to bind the ingredients.

Biological type effects on gestation length, calving traits and calf growth rate.

Gestation length, birth weight calving difficulty, calf mortality rate at birth, calf mortality rate from birth to weaning, preweaning calf growth rate and calf 200-d weight were evaluated in a biological type study in which four sire breeds were bred by AI to Hereford dams. Angus and Red Poll sires represented breeds of medium size, and Pinzgauer and Simmental sires represented large breeds. Angus and Pinzgauer represented breeds with medium milk production, and Red Poll and Simmental represented breeds with high milk production. Dams mated to large sire breeds had longer (P less than .01) gestation lengths (.95 d) and higher calving difficulty scores than dams mated to medium-sized sire breeds. Calves from large sire breeds had heavier birth weight (P less than .01) and 200-d wt (6.1 kg; P less than .01) than calves from medium-sized sire breeds. Calf death loss and ADG to weaning were similar (P greater than .10) for all breeds of sire. Calves from the higher milk level sire breeds exceeded the medium-milk breeds in birth weight (1.3 kg; P less than .01) but did not (P greater than .10) in other traits. Calves from the higher milk level sire breeds exceeded the medium-milk breeds in birth weight (1.3 kg; P less than .01) but not (P greater than .10) in other traits. Interaction between size and milk production of sire breed existed for gestation length, birth weight, ADG from birth to weaning and 200-d calf weight (P less than .01). In general, mature size of sire breed was a good indication of expected performance traits not easily influenced by environment. Not all differences, however, could be explained by size and milk production of the size breed.

Effect of bovine somatotropin on the growth rate, hormone profiles and carcass composition of holstein bull calves

A study was conducted to determine the effects of BST on the growth rate, hormone profiles and carcass composition of preweaned Holstein bull calves. Injection of BST resulted in increased average daily gains and feed intakes (P<.05) compared to that of control animals. This increased rate of gain coupled with increased intakes resulted in identical feed conversion efficiencies between treatments. Fractional weights (organ weight/body weight) of selected organs and tissues were unaffected by BST treatment. Carcass fat percentage was reduced in BST-treated calves (28.1 ± 1.18% and 32.8 ± 1.84% for BST and controls groups respectively, P<.05) while no differences were seen for carcass DM, CP, ash or gross energy content. Plasma BST levels were higher (P<.0001) in BST treated calves while plasma IGF-1 levels were not different between treatments. Plasma IGF-1 concentrations correlated (P<.0001, R = .71) with average daily gains. The results of this trial suggest that growth responses are inducible with BST in young calves (7 days to 3 months).

The detection and measurement of stray electrical leakages on dairy farms: effects on performance

Sources of stray electrical leakage from Power Supply Authority alternating current (AC), fence energiser pulses and randomly generated pulses and spikes on 55 dairy farms in the Waikato area were identified between December 1986 and March 1988. The electrical measurements were made using a specifically designed voltmeter able to detect voltages between 0.1V and 1500V, from single voltage spikes of two microseconds or greater duration from direct current (DC) as well as 50 Hz AC. Ninety-five sources of stray voltage were identified, and 53 per cent of properties had more than one source of >0.5V. The major source was from electric fence energisers. Rotary platform parlours were among the commonest sources of random or transient voltage spikes. Leakage of AC into one or other of the components of the milk transport system such as vat, plate cooler, milk lift pump and milk line was common. Owners acknowledged the improvements in milk production, reproductive performance and growth rate of calves after reduction of the exposure of dairy cattle to stray electrical leakage. A representative summary of five case records helps define the range of improvements that may possibly be achieved.

Effect of Prepartum Feeding on Milk Yield and Calf Growth Rate in Limited-Suckled and Nonsuckled Buffaloes

Two experiments were conducted to measure response to prepartum feeding using 101 Nili-Ravi buffaloes of mixed ages and lactation numbers. Nutritional treatment was initiated approximately 75 d before calving and stopped at parturition. Levels of prepartum feeding were moderate and high in Experiment 1 and high and very high in Experiment 2. Estimated daily intakes of metabolizable energy by buffaloes on moderate, high, and very high intake treatments were 31.9, 45.8, and 50.6 Mcal, respectively. Prepartum feeding affected the BW gain by buffaloes in both experiments. Yields of milk and milk fat for first 75 d were greater for buffaloes on higher prepartum feeding treatments. In Experiment 2, buffaloes suckled for a limited time produced more milk than nonsuckled buffaloes, but the difference was small. Calf birth weight increased with increasing prepartum feeding in both experiments. Gain in BW of buffalo calves from birth to 75 d of age had no relationship with birth weight. In Experiment 2, calf weight gain was influenced by the interaction of dam's prepartum feeding and suckling. In conclusion, improvement in prepartum feeding can be used to increase milk yield and birth weight of Nili-Ravi buffaloes.

Efficient and effective cow feeding

The financial success of beef cow enterprises depends to a large extent on efficient control of cow feeding. The fact that the single suckled beef cow has to be maintained for a whole year to produce one calf means that the cost of feeding the cow represents the biggest single variable cost. Thus winter feeding must be controlled to ensure the correct balance between feed inputs and cow and calf performance, and summer grazing management must be designed to ensure high animal performance, high output per hectare and efficient grassland utilization.Eighty percent of foetal growth occurs during the last 3 months of pregnancy and so any effect of energy restriction on calf birth weight should be most evident at that time. Russel et al (1979) showed that relatively severe levels of undernutrition were required to reduce calf birth weight by 10-15% and that subsequent calf viability and growth rate were unimpaired.

Factors Affecting Reproductive Efficiency in Beef Cows

Successful and timely rebreeding is of major importance to the economics of suckler cow enterprises. Research into the causes of reprodutive failure and extended calving intervals can be difficult, not least because of the need for experiments involving large numbers of animals if statistically significant treatment effects are to be demonstrated. Useful information however, can be obtained from the analysis of data derived from a number of relatively small-scale experiments, not necessarily on reproduction per se, but in which records of reproductive performance are available.This paper deals with the analysis of data on the reproductive performance of beef cows used in a number of experiments on the effects of nutrition during pregnancy and lactation on components of production such as milk yield and composition, calf birth weight and early calf growth rate. The objective of the analysis was to identify the major factors affecting calving interval and to quantify the magnitude of the effects of these factors.

Plasma prolactin concentrations in barren, pregnant and lactating red deer ( Cervus elaphus) given melatonin to advance the next breeding season

The objectives of this trial were to investigate the effects of melatonin treatment initiated in May on plasma prolactin concentrations, growth rate of suckled calves and onset of seasonal oestrous cyclicity in red deer hinds which were either barren or gave birth on average 37 days after the start of treatment. Six barren and nine pregnant/lactating hinds were each given 5 mg melatonin daily in a feed at 15.30 h from 6 May to 22 September. Six barren and nine pregnant/lactating deer served as controls by receiving the feed unsupplemented. Plasma prolactin concentrations in control deer increased during May (from about 10 to 40 ng/ml), remained high in June and July (barren: 30–40 ng/ml, lactating: 50–80 ng/ml), and decreased by the end of August to reach basal values (0–7 ng/ml) thereafter. Melatonin treatment significantly lowered plasma prolactin concentrations to basal levels after 21 days (i.e. end of May) in barren hinds, but not until 14 days post-partum in the pregnant/lactating animals (i.e. end of June) after an average of 51 days of treatment. Calves grew at the same rate (g/day, mean ± SEM) whether suckled by melatonin-treated (321 ± 5.9) or control (326 ± 8.1) hinds. Mean onset of seasonal ovarian activity was advanced by melatonin treatment in lactating hinds (38 days, P < 0.001) and non-lactating hinds (33 days, P < 0.01). In a second concurrent experiment, barren hinds kept indoors in natural daylength were given melatonin as above ( n = 2) or remained as untreated controls ( n = 2). Prolactin showed two or three distinctive phases of increased plasma concentrations in blood samples taken hourly over intermittent 24-h periods, even when baseline values were undetectable for some of the time, and treatment with melatonin apparently induced a phase-shift in this diurnal pattern.

GENOTYPE × ENVIRONMENT INTERACTIONS FOR BEEF COW PERFORMANCE DURING LACTATION

Genotype × environment interactions for beef cow performance traits expressed during lactation were evaluated for 10 F1 cow crosses. The crosses (genotypes) were represented by the Hereford-Angus (HA) and nine crosses produced by mating Charolais (C), Simmental (S), and Limousin (L) sires with cows of Hereford (H), Angus (A) and Shorthorn (N) breeding. Environmental differences were provided by two climatically distinct locations (Brandon, Manitoba; Manyberries, Alberta) with two treatments (drylot confinement vs. pasture) imposed at each location in each of 3 consecutive years. The total data set comprised 1274 cow-calf pairs with milk production data recorded for 730 lactations. Substantial (P &lt; 0.01) year, treatment and breed cross effects were present at each location for virtually all of the traits evaluated (cow weights and average subcutaneous fat, weight and fat changes during lactation, milk yield, calf growth rate, conception rates). Substantial (P &lt; 0.0001) year × treatment interactions were also present. No genotype × environment interactions (year × breed cross, breed cross × treatment) were identified at either location for preweaning growth rate of calves, average daily milk yield of the cows or date of conception. Location differences were large for all of these traits, but rankings of the breed crosses at the two locations were in close agreement, indicating the absence of any location × genotype interactions. The ranking of breed crosses for conception rate was unaffected by treatment or year within each location, but the rankings did differ between locations. Under the environment provided at Manyberries conception rates tended to be inversely related to average milk yield of breed crosses, while no such relationship was evident under die conditions at Brandon. Key words: Genotype × environment interaction, beef cattle, cow productivity, calf performance

BEEF CATTLE REPRODUCTION IN RELATION TO THE ENVIRONMENT

Results are reported from a 10-yr study of lifetime reproductive performance of beef cows maintained under two contrasting environments. The data comprised records for 8160 cow years. The breeding herds were maintained for 6 yr in accordance with the management practices conventional to each location with winter management changed (to drylot feeding) for the final 4 yr. Location differences in cow performance favored the herd maintained under semi-intensive management (Brandon, Manitoba). Conception rates were higher, calf mortality lower, and calf gains preweaning greater than recorded for the contemporary herd maintained under extensive range management (Manyberries, Alberta). These differences in performance gave Brandon a 16% advantage in weight of calf weaned per mating exposure. Cows at Manyberries, in the fall of 1977, the seventh year of study, were lighter (15%) and had less fat (60%) than their Brandon contemporaries. These differences increased to 19 and 80% during the first winter in feedlot confinement even though the daily feed energy allowance was 20% above requirements (National Research Council-National Academy of Sciences, NRC-NAS). Conception rates at Manyberries were seriously affected by mortality, both cows and calves, inversely related to cow fat at calving. An increase in feed inputs at Manyberries (42% above NRC-NAS) the following winter, coupled with the opportunity for tissue restoration provided by a barren year, reversed the downward trends in weight and fat and weight equivalence of the two herds was achieved by 1980. Milk yields from pastured cows during the last 4 yr were generally higher for the Brandon herd, but calf growth rate from birth to 2 mo of age was greater at Manyberries. Key words: Beef cows, reproductive performance, lifespan, environment

PASTURE STRATEGIES FOR DAIRY BEEF PRODUCTION

Improved pasture species, irrigation and nitrogen fertilizer options for increasing pasture growth rate during inter and Summer have been evaluated in growth rate and annual production of young Friesian bulls. Effective increases in Summer pasture production have been obtained from the use of irrigation, Pawera red clover, Matua prairie grass and particularly a combination of irrigation and Matua, Nitrogen fertilizer, Matua and carryover effects of irrigation have increased cool Season pasture growth rates. Liveweight gains reflect these increases except on Matua pastures where poor growth rate of calves occurs durmg summer. The negative effects of the different pasture treatments on Spring liveweight gain are attributed partly to the effects of compensatory growth in bulls but also to treatment effects which reduce pasture growth rate during this season. For this reason the most effective gains are made by 15-18 month old bulls during summer. Pasture species and pasture mixtures react differently to applications of irrigation and nitrogen fertilizer. The most appropriate Strategies and combinations are discussed

Growth rates of calves resulting from aggregated embryos

Growth rates of calves resulting from aggregated embryos

Effect of Environmental Temperature and Dietary Fat on Growth and Physiological Responses of Newborn Calves

Effects of cold environmental temperature and supplemental dietary fat (energy) on growth rate and physiological responses of young dairy calves fed a milk replacer diet were studied. Thirty-six Holstein bull calves were randomly assigned to one of six treatments allotted in a 2(−4°C or 10°C)×3(10, 17.5, or 25% dietary fat) factorial arrangement of treatments Calves began the experiment at an average of 6 d of age and received .6kg dry milk replacer in 4L of water daily for 3 wk. Average daily gains (kg/d) over the 3-wk trial for calves fed 10, 17.5, and 25% fat diets were −.04, .02, and .09 at −4°C and .15, .22, and .20 at 10°C. Gains were significantly lower for calves housed at −4°C. Rectal temperatures were lower for calves at −4°C than at 10°C and for calves fed 10% versus 25% fat diet. Respiratory rates and water intakes were lower for calves housed at −4°C but were not affected by diet. Concentrations of plasma glucose and prolactin were lower for calves housed at −4°C while concentrations of plasma free fatty acids and growth hormone were not affected by temperature. Plasma free fatty acids were increased by dietary fat, and plasma growth hormone was reduced as dietary fat increased. Calves housed at −4°C had higher maintenance energy requirements (.133 Mcal metabolizable energy/kg·75) than calves housed at 10°C (.101 Mcal metabolizable energy/kg·75). Consequently, calves housed at −4°C require 32% more energy for maintenance than calves housed at a temperature within their thermoneutral zone.

Post-partum reproduction in swamp buffalo cows at two feeding levels

Post-partum progesterone secretion, oestrus, and conception were monitored in two groups of eight swamp buffalo cows which were fed at “low” or “high” levels from 12 weeks before until 36 weeks after calving. Calf birth weights and pre-weaning mortality were not affected significantly by nutritional treatment, but the average growth rates of calves from birth to weaning at 26 weeks of age were greater ( P<0.01) at the high (0.39 kg/day) than at the low (0.26 kg/day) feeding level. In five cows from each group which reared calves to weaning, average post-partum intervals to first oestrus were 190 and 144 days ( P<0.10), and average post-partum intervals to conception were 222 and 169 days ( P<0.05), at the low and high feeding levels, respectively. Plasma progesterone profiles indicated that normal post-partum luteal function at both feeding levels was commonly preceded by transient corpora lutea with subnormal progesterone secretion. Mean body weights at conception did not differ significantly between the two groups, suggesting that earlier post-partum conception in cows at the high feeding level was associated with their lower body weight loss and/or their faster body weight recovery after calving.