Post-calving Weight Research Articles

Service Sire Effects on Body Condition Score, Milk Production, and Rebreeding of Mixed-Aged Dairy Cows Bred to Angus and Hereford Bulls—A Case Study in New Zealand

Beef-breed bulls are used in dairy herds to produce a calf of greater value for finishing than calves sired by dairy bulls. There is limited research about which beef-breed bulls are most appropriate, and whether any negative impact on cow performance in terms of milk production and rebreeding should be considered. The aim of this case study was to compare the body condition score, milk production, and rebreeding performance of mixed-aged dairy cows bred to a selection of Angus and Hereford beef-breed bulls. Body condition score, post-calving live weight, milk production, rebreeding performance, and survival of 952 mixed-aged dairy cows artificially bred to 65 Angus and Hereford bulls were compared. There was no effect of service sire on post-calving live weight, days in milk, milk production, or inter-calving intervals of mixed-aged cows. Service sire had an effect on the calving day due to differences in gestation length (p < 0.001), although this did not translate into an effect on days in milk. A longer gestation length negatively influenced pregnancy rates, and greater birth weight of the calf negatively influenced survival to rebreeding (p < 0.05), indicating the potential for an effect of service sire. Selection of beef-breed service sires for dairy cows should include emphasis on lighter calves and shorter gestation lengths. The general absence of the service sire effect on the parameters measured in this study indicated that any of the service sires used in this experiment would be appropriate for use over dairy cows.

Designing a replacement heifer rearing strategy: Effects of growth profile on performance of Norwegian Red heifers and cows

The primary objective of this study was to design a growth profile from 3 mo through puberty to insemination that allows heifers to enter the milking herd at 22 mo of age without impairing milk production over 3 lactations compared with the current rearing practice leading to an age at first calving of 26 mo. Eighty heifers born into the Norwegian University of Life Sciences herd, 40 each from yr 2010 and 2011, were randomly assigned according to birth order either to a high or low intake energy treatment. Each energy group was further subdivided into 2 protein groups, 1 fed according to requirements and 1 fed 10% excess protein, to ensure that metabolizable protein supply would meet the requirements for rapidly growing bone and muscle of today's genetically improved Norwegian Red heifer. Utilizing growth rate and feed composition the energy and protein supply was regulated with roughage quality in a diet containing 1 kg/d of concentrate of 2 qualities. Average daily gain from 3 mo to confirmed pregnancy ranged from 900 to 1,000 g/d among high-energy animals, with high protein-fed animals growing the fastest. Growth rates for low energy animals were <700 g/d. From confirmed pregnancy to first calving, all animals were fed only grass silage to sustain an average daily gain <500 (high energy) or >600 g/d (low energy), excluding fetal and gravid uterus weight, and they reached a postcalving weight of 530 (high energy) to 570 kg (low energy) with body condition score ranging from 3.42 to 3.93 at calving. We have shown that heifers fed a high-energy treatment with the required amount of protein from 3 mo of age to successful insemination combined with an average daily gain of ∼500 g/d throughout pregnancy will calve at 22 mo without becoming over-conditioned at calving and without impairing performance over 3 lactations. We recommend reducing rearing time by 4 mo, planning for an age at first calving of 22 mo of age. This rearing practice would also improve energy efficiency during the heifer rearing period.

Effect of reproductive rest on the subsequent breeding in Iberian red deer hinds ( Cervus elaphus hispanicus)

The objective of this study was to examine the effects of reproductive rest during the preceding year on subsequent breeding in captive Iberian hinds. To achieve this, influences were assessed on hind weight at mating, precalving and postcalving weight, hind body condition at mating, hind weight gain during gestation, hind weight loss at calving, total milk yield and calf birth weight during the following breeding season. Sex ratio was examined according to hind age class (sub-adults or adults), precise age, body condition and weight at mating, and reproductive rest. One hundred and twenty seven gestations and their subsequent lactations were analyzed in pluriparous Iberian red deer ( Cervus elaphus hispanicus) kept in captivity for two years. Sixty four of these gestations (50.4%) took place after no gestation during the preceding year. Hinds that did not gestate the preceding year were heavier at mating and after calving, gained less weight during gestation, and their body condition at mating was better than those hinds that had gestated. Also, calves from hinds that had reproductive rest the preceding year were heavier at birth than the others. Nevertheless, the probability of bearing a male was greater with increasing age, but not with reproductive rest or any other variable. Total milk yield was positively affected by hind postcalving weight and hind age at mating, but not by reproductive rest. In conclusion, reproductive effort during the preceding breeding influenced the subsequent gestation, having an effect on the following variables: hind weight and body condition at mating, hind weight gain during gestation, postcalving weight, and calf birth weight.

Hind body condition and weight in primiparous of Iberian red deer (Cervus elaphus hispanicus) with one, two or three years old at mating

Several studies of mammals have examined the fitness consequences of the age of primiparity, due to primiparous hinds face a trade-off between reproductive effort at first breeding and body growth. Physical condition of hinds is the most important factor determining whether individuals became pregnant. In fact, in yearling hinds there is a positive effect of premating body weight on conception and the onset of puberty depends on her body weight. In addition reproductive effort at first breeding should reduce the amount of body reserves available for growth and maintenance, potentially reducing residual reproductive value.This study examined 103 primiparous hinds of Iberian red deer (Cervus elaphus hispanicus) with one (n=75), two (n=21), or three (n=7) years old at mating, from 1998 up to 2006. They were kept in a 30000 square meters opendoor in the Experimental Farm of Castilla-La Mancha University in Albacete (38° 57′ 10″ North, 1° 47′ 00″ West and 690m above sea level) and they had ad libitum access to food and water. Hinds were weighed weekly on a ± 50g electronic balance, and then they were driven to a small handling box to asses their body condition. General Linear Models were used to examine the effect of the age at first breeding on the following variables: hind weight at mating, precalving and postcalving, weight gain during gestation, weight lost at calving, mating body condition and calf birth weight. The GLMs performed showed a significant effect of hind age at first breeding on mating weight (coefficient: 7.15 ± 1.67; P <0.001), precalving weight (coefficient: 6.31 ± 1.83; P <0.01), and postcalving weight (coefficient: 6.17 ± 1.59; P <0.001), improving all of these variables with hind age. Mating body condition was affected by hind age (P <0.05) too, being greater in primiparous with one year at mating than in those hinds with two or three mating years. Also, the monthly trend in body condition during gestation was different in the three groups of hinds; in hinds with one year at mating body condition improved during two first months, beginning to decrease in the third month of gestation while in the other groups of hinds it was improving practically during all gestation.On the other hand, the minimum mating weight observed to achieve a successful reproduction was 53.5, 58.5, or 71kg in primiparous with one, two or three mating years respectively. Finally, no differences were observed between groups in weight gain during gestation, weight lost at calving or calf birth weight.

Stockpiled forage or limit-fed corn as alternatives to hay for gestating and lactating beef cows.

In Exp. 1, 31, 24, and 17 mature, pregnant Simmental x Angus cows (initial BW = 662.0 +/- 10.4 kg) in each of 3 yr were used to determine the efficacy of stockpiled orchardgrass, limit-fed corn, or ad libitum hay for maintaining cows in mid- to late gestation, respectively. In Exp. 2, 24 mature, pregnant crossbred cows (initial BW = 677.7 +/- 9.4 kg) per treatment in each of 3 yr were used to determine the efficacy of stockpiled orchardgrass, limit-fed corn, or ad libitum hay for maintaining cows in late gestation and early lactation, respectively. Each year, cows were assigned to treatment by BW. From November to February or from January to April, respectively, nutritional needs for mid- to late gestation (Exp. 1) or late gestation and early lactation (Exp. 2) were met either by 1) rotating cows on approximately 15.2 or 21.7 ha of predominantly orchardgrass pasture, set aside and fertilized in late August, 2) limit-feeding approximately 5.8 kg of whole shelled corn, 1.1 kg of a pelleted supplement, and 1.2 kg of hay daily, or 3) ad libitum feeding of round-baled hay. During extreme weather conditions, cows grazing stockpiled orchardgrass were limit-fed a grain-based diet. Postcalving weight (P < 0.10) was greatest for limit-fed cows in Exp. 1 and lowest for cows grazed on stockpiled orchardgrass; cows given ad libitum access to hay were intermediate in weight and did not differ from cows limit-fed or cows grazed on stockpiled orchardgrass (641.8, 657.4, and 634.0 kg, respectively). Calving date, calf birth and weaning weight, and conception rate did not differ among treatments (P > 0.15) in Exp. 1. In Exp. 2, weight at weaning did not differ among treatments (P > 0.17); however, postcalving weight (P < 0.01) was greatest for cows given ad libitum access to hay, intermediate for limit-fed cows, and lowest for cows grazed on stockpiled orchardgrass (674.8, 652.4, and 624.5 kg). Body condition score at any time point did not differ among treatments (P > 0.38), nor did calving date, calf birth and weaning weights, and conception rate (P > 0.12). Because of the few differences in cow performance, selection of energy sources for beef cows can be made based on economics. The cost to feed a cow hay in early to mid-gestation was nearly double that of limit-feeding the corn-based diet or grazing stockpiled orchardgrass. Because of lower quality pastures, the cost to graze cows on stockpiled orchardgrass during late gestation and early lactation was not as cost effective as limit feeding a corn-based diet.

Predicting requirements for growth, maturity, and body reserves in dairy cattle.

The 1996 National Research Council Nutrient Requirements of Beef Cattle equations used to compute growth requirements, target weights, and energy reserves were modified and evaluated for use with dairy cattle. Coefficients used to compute target weights during growth and equations used to predict body weights (BW) for each condition score in computing energy reserves were modified. Equations used to compute net energy and protein requirements for growth were evaluated with data from studies of body composition changes in Holstein heifers; this model accounted for 96% of the variation in energy retained with a 4% bias. Coefficients used to compute target growth rates and BW were evaluated with data from Holstein heifer growth studies. Actual and target shrunk weight gain and BW values were before first pregnancy, 0.82 versus 0.87 kg/d with a 370-kg weight at first pregnancy versus a target of 352 kg; during the first pregnancy, 0.63 versus 0.69 kg/d with a weight at post first calving of 533 versus 545 kg; and first lactation, 0.136 versus 0.104 kg/d with a second post-calving weight of 592 kg versus 590 kg. The equations used to predict body reserves from BW and condition score were evaluated with data from a study of body composition associated with body condition score in Holstein cows; the revised model accounted for 96% of the variation in body fat and predicted 80 kg shrunk BW change per body condition score compared to 85 kg observed.

Prediction of voluntary intake of grass silages by lactating cows offered concentrates at a flat rate

ABSTRACTData for individually recorded silage dry-matter intake (SDMI), concentrate dry-matter intake (CDMI), live weight, milk yield and milk composition of lactating dairy cows offered silage ad libitum and concentrates on a flat-rate basis, together with data for silage composition from experiments conducted at four sites, were used to obtain simple and multiple regressions of SDMI on other variables.Simple regressions showed that the most important variables affecting SDMI were, in order of importance: silage ammonia nitrogen, fat yield, CDMI, silage digestible organic matter concentration (DOMD) and live weight. The best multiple regression for the mean SDMI over weeks 4 to 13 of lactation accounted for proportionately 0·649 of the variation. Examination of week by week data for weeks 3 to 20 of lactation showed that two models for early and mid lactation were required to give a reasonable pattern of residual variances. These models accounted for 0·627 and 0·581 of the variation respectively. It was necessary to fit time effects explicitly in early lactation. Live weight was best represented by fitting post-calving live weight and deviations from post-calving live weight separately. A number of models requiring fewer input variables were also obtained to allow for use in situations where the full range of measurements is not made.The new models were tested using independent data from three sites. They performed better than a number of previously published models but the best model still gave a prediction error of proportionately 0·17 about the mean actual silage intake in early lactation and 015 in late lactation.The results suggest that there is little to be gained from further refinement of the functional form of the models and that the construction of a number of models for specific food and management situations is preferable to the use of global models.

Beef x beef and dairy x beef females mated to Angus and Charolais sires. I. Pregnancy rate, dystocia and birth weight.

Pregnancy rate of 310 females and birth weight, dystocia score and percentage of assisted births among 910 calves born from 1972 through 1977 were examined. Dams were 2 to 7 yr old and of Angus x Hereford (AH), Charolais x Hereford (CH), straightbred Hereford (HH) and Brown Swiss x Hereford (SH) breed types. Females were exposed to A and C bulls. Breed of dam affected (P less than .01) dystocia score (DS), percentage of assisted births and birth weight. When adjusted for birth weight of calf and dam's postcalving weight, CH and SH dams generally differed (P less than .01) from AH and HH dams in percentage of assisted births and DS. The AH and HH dams were not different (P greater than .01) in percentage of assisted births, DS or birth weight of calf. C-sired calves had higher birth weights (P less than .01) and their dams had higher DS (P less than .05). However, there was no difference between C- and A-sired calves in percentage of assisted births when data were adjusted for effects of birth weight of calf and weight of dam. Calf sex affected birth weight (P less than .01) but had little influence on DS or percentage of assisted births when birth weight was held constant. Male calves were 1.7 kg heavier at birth than females. Two-year-old dams had higher (P less than .01) DS and percentage of assisted births than did dams in all other age groups. Age of dam influenced birth weight (P less than .01), with paired comparisons of age classes showing differences between all age groups except 4- and greater than or equal to 5-yr-old cows. Year of birth was a source of variation (P less than .05) for all traits measured. In 1972, there was a higher mean DS and a higher percentage of assisted births (P less than .05) than in any other year. However, all calves born in 1972 were from 2-yr-old cows. Percentage difficulty and DS increased linearly (P less than .01) with birth weight. Each 1-kg increment in birth weight increased percentage difficulty by 2.6 percentage points and DS by .04 units. Dam's with heavier weights had calves that were heavier (P less than .01) at birth, but dystocia tended to decrease. Condition entering the breeding pasture influenced (P less than .05) pregnancy rate among 2- to 7-yr-old cows. Thin (score w) cows had a lower conception rate than average flesh (score 3) or fat (score 4) cows. Date of calving prior to the breeding season also affected (P less than .05) pregnancy rate. Each 10 d later calving resulted in a 1.2% reduction in conception rate. No significant sources of variation were observed for pregnancy rate among yearling heifers. Pregnancy rates ranged from 97.1% for CH and SH heifers to 86.9% for HH females. Yearling AH females were intermediate at 93.5%.

Post-calving nutrition of single-suckled Angus beef cows

The post-partum performance of Angus single-suckled beef cows calving in the spring, and that of their calves, was observed in a series of five experiments in 1971–1975, with 50, 48, 52, 83, and 86 cows in each year respectively. A sawdust pad was used on which cows were confined so that their nutrition could be controlled. In the first four experiments (1971–1974) all cows allocated to the sawdust pad on the lower level of nutrition remained there until the middle of September when the mean calf age was approximately 30 days. In the fifth experiment (1975) cows allocated to the sawdust pad were removed with their calves when these were at one of three ages: 1 day old, or 20 or 40 days old. With the exception of an increase in calving interval of 20 days (P < 0.01) after low post-calving nutrition in Experiment 3 (1973), there did not appear to be any effect on production variables in Experiments 1–4, despite post-calving weight losses of up to 15% based on the pre-calving live weight of the cows. In Expe...

The health and performance of cows fed large amounts of urea

SUMMARYFrom 6 weeks before calving to the end of lactation 2 groups of 8 cows were fed a ration incorporating a dairy nut containing 29 g/kg urea or an isocaloric isonitrogenous nut containing fish-meal and groundnut. During the 18 weeks after calving, concentrates were fed to appetite. 305-d yields of milk (7023 and 5796 kg) and lactose (345.7 and 273.4 kg) were significantly lower in the urea-fed cows (P&lt; 0·05). Intakes of dry matter, metabolizable energy and digestible crude protein were similar in both groups until 18 weeks after calving when feeding according to yield commenced, but by 6 weeks after calving the urea-fed cows lost only 5% of their immediate post-calving weight compared with 7% in the controls. There was no evidence of ammonia toxicity in the urea-fed cows. Blood glucose concentrations were similar in both groups, but higher serum urea concentrations in the urea-fed cows suggested that there was poor utilization of ingested N. A model proposed by Royet al.(1977) has been used to calculate the requirements of rumen-degradable protein and undegraded protein (UDP) of the 2 groups from their energy intakes and milk yields. Between 4 and 11 weeks post-calving, dietary requirement for UDP closely matched intake of UDP. It is concluded that UDP intake was a major factor in determining the peak milk yield. Mechanisms by which the degradability of the dietary protein might influence milk yield are discussed.

AN EVALUATION OF SEVERAL MEASUREMENTS OF BEEF COW SIZE AS RELATED TO PROGENY PERFORMANCE

A study with 173 cows from the University of Alberta beef breeding herd (1969–1970 data) was conducted to investigate the interrelation of cow body-size variables and the effect of selected cow-size variables on calf performance. The cows were classified into two breed categories: Hereford and Angus–Galloway crosses (HEAG) and hybrid and other breed crosses (HYC). Measurements of cow body-size included: postcalving weight (PCW), weight when calves were weaned (WCW), height at withers (HW), height at sacrum (HS), and average wither-sacral height (H), body length (L), and heart girth (G). Heart girth was more highly correlated with body weight than either length or height measurements, indicating that G reflects condition of animal, whereas L and H measurements tend to reflect skeletal size. Body weight was highly correlated with both PCW/H and WCW/H ratios. Weight–height ratios appeared to reflect condition; WCW/H was considerably higher than PCW/H (4.13 vs. 3.32 for HEAG and 4.02 vs. 3.15 for HYC). Across breed and age of dam a 10-kg increase in PCW resulted in a 0.7-kg increase in weaning weight of calf. A 1-cm increase in H resulted in a 0.97-kg increase in weaning weight of calf. Within breeds, preweaning performance of calves was more closely associated with H than with PCW in HEAG dams and about equal to H and PCW in HYC dams. Postweaning average daily gain was positively associated with both PCW and H for HYC dams but negatively associated with PCW for HEAG dams. For HEAG dams a 10-kg increase in PCW resulted in a 0.47-kg decrease in final weight of male calves and a 1-cm increase in H resulted in a 3.7-kg increase. For HYC cows, a 10-kg increase in PCW resulted in a 1.91-kg increase in final weight of male calves and a 1-cm increase in H resulted in a 0.82-kg increase in final weight of male calves.

FACTORS INFLUENCING MILK YIELD OF BEEF CATTLE

The joint and separate effects of several cow-calf variables on milk yield were studied with 176 and 201 beef cows from the University of Alberta beef breeding herd for 1966 and 1967, respectively. The dams consisted of Hereford, Aberdeen Angus, Galloway and hybrid breeding. Independent variables considered were: breed, post-calving weight, winter weight loss, summer weight gain and age of dam, and weaning age, sex and birth weight of calf. Total variance of milk yield explained by all variables together was only 40 and 52% for 1966 and 1967, respectively. Breed and age differences of dam accounted for 82 and 87% of explained variance in milk yield respectively for 1966 and 1967. Holding cow age constant, post-calving weight of cow explained 0.0 and 8.5% additional variance in milk yield for 1966 and 1967, respectively. Summer weight gain of cow was negatively associated with milk yield. Winter weight loss of cow had little influence on milk yield. There appeared to be a negative relationship between early parturition and milk yield. The effect of calf sex on milk yield of dam was inconsistent; cows suckling male calves vs. female calves yielded more milk in 1966 but less in 1967. Birth weight of calf had a small positive influence on milk yield of dam. Association between milk yield of dam and preweaning performance of progeny was high. It appeared that the quickest way to improve milk yield in beef cattle would be the introduction of breeds noted for high milk yield and by indirect selection, through selection of dams with progeny that have high average daily gain to weaning.

FACTORS AFFECTING PREWEANING PERFORMANCE IN BEEF CATTLE

Two years data involving 176 and 201 cows from the University of Alberta beef breeding herd were used to study the influences on calf preweaning performance of: breed, age, weight, summer and winter weight changes and milk yield of dam; breed of sire; and birth weight, weaning age and sex of calf. All independent variables combined explained 73 and 70% of total variance in average daily gain (ADG) to weaning and 81 and 70% of total variance in weaning weight, respectively, for 1966 and 1967. Of all variables considered, milk yield had the greatest influence on preweaning performance, explaining about 60% of the variation in ADG to weaning and 40 to 50% of the variation in weaning weight. A 1-kg increase in daily milk yield resulted in an 11- to 14-kg increase in weaning weight. Breed of dam explained about 23% of total variance in ADG to weaning, most of which was accounted for by breed differences in milk yield. Breed-of-sire differences accounted for 5.7 and 1.4% of variance in ADG of progeny for 1966 and 1967 data, respectively. Male calves exceeded female calves in birth weight by 2 kg, in ADG to weaning by 0.03 kg, and in weaning weight by 8 to 9 kilograms. Birth weight was positively associated with calf growth rate. A 1-kg increase in birth weight resulted in 1.74- and 1.59-kg increases in weaning weight for 1966 and 1967, respectively. A 10-kg increase in post-calving weight of cow, independent of milk yield and cow age, resulted in approximately a 0.7-kg increase in weaning weight of calf. Average daily gain to weaning was influenced slightly more by cow age than by post-calving weight of cow. However, about 80% of the variation in ADG explained by either cow age or post-calving weight of cow was accounted for by differences in milk yield associated with either variable.

The growth rate of heifers in a dairy herd

Growth rates of Shorthorn and Friesian heifer calves from 0 to 6 months of age were studied from live-weight data collected over a 10-year period.Friesian calves were heavier than Shorthorn. Male calves were heavier than female. Calves born to the first pregnancy were smaller than those born to later ones. Gestation length was 5 days shorter for Friesian than for Shorthorn cows. It tended to be slightly shorter for female than for male calves. Non-foetal loss of weight at calving was greater with male than with female calves.High-level feeding before calving was associated with heavier calves but the effect was not statistically significant.Calf birth weight increased by 0·026 lb./lb. increase in post-calving live weight of the dam and by 0·564 lb./day extension of the gestation period.Growth rate accelerated from birth to 3–4 months of age and then declined slightly. Autumn-born calves grew faster in the first 90 days than springborn calves. Age of dam and level of feeding before calving had no effect on rate of growth of the calf.For both breeds there were significant negative correlations between birth weight and rate of gain in the first month after birth.