Calving Systems Research Articles

Seasonality of calving in pasture-based dairy systems: its effects on herbage production, utilisation and dry matter intake

The objectives of the present work were to evaluate the influence of season of calving on (i) pasture productivity, (ii) total dry matter intake by cows, and (iii) the relationship between intake and milk yield of individual cows. Three systems in which the cows calved either in autumn, in spring or half in autumn, half in spring, were managed according to a set of common guidelines during 3 consecutive years. Herbage accumulation rate (HAR) was estimated by the difference between 2 successive grazings (pre- and post-grazing herbage mass). Average HAR in each month was similar between systems. However, small differences in HAR were observed between calving systems in spring and summer, and appeared to be related to the proportion of the farmlet closed for silage. Herbage dry matter intakes varied seasonally (P<0.05), but independently of the calving system (P>0.05). Cows from different calving systems, offered 8.9 or 2.5 kg maize silage dry matter per cow daily in the paddocks, consumed an average of 6.0 and 1.4 kg, respectively. A large variation in intake was observed between individual cows with ranges from 2 to 10 kg and 0.2 to 2.9 kg, respectively. In conclusion, applying the same grazing management decisions to systems with contrasting calving dates resulted in only small seasonal, but not annual, differences in pasture HAR. The results also indicated that when maize silage is fed in the paddock, wastage can be high and variation in intake between individual cows can also be large.

Prevention of Neonatal Calf Diarrhea with the Sandhills Calving System

Neonatal diarrhea remains an important cause of illness and death of beef calves. Costs of the disease include loss of performance, mortality and the expense of medication and labor to treat sick calves. In addition, cattle producers often become disheartened after investing long hours to treat scouring calves during an already exhausting calving season. Our objective was to design and test calving systems that would reduce morbidity and mortality due to neonatal calf diarrhea.

Comparison of a pasture‐based system of milk production on a high rainfall, heavy‐clay soil with that on a lower rainfall, free‐draining soil

AbstractThe objective of this study was to compare the biological and economic efficiency of a seasonal pasture‐based spring calving system of milk production on a high‐rainfall, heavy‐clay soil [Kilmaley (KMY)] to that on a lower‐rainfall free‐draining soil [Moorepark (MPN)] in Ireland. The physical performance data were obtained from a 3‐year study (1998–2000) carried out at both sites. Analysis of the system of milk production at the two sites was undertaken using the Moorepark Dairy System Model. Herbage dry‐matter production was greater at the MPN site with a greater proportion being produced between 1 September and 1 May. On average, over the 3 years, the system of milk production at the MPN site had a higher stocking rate (2·34 vs. 1·89 cows ha−1), higher milk production per cow (6421 vs. 5781 kg per cow), longer grazing season (250 vs. 149 d) and a higher proportion of the diet of the herd from grazed grass (0·70 vs. 0·40) than at KMY. Economic analysis showed that, in a 468 100 kg European Union milk quota scenario, the profitability at the MPN site was €28 417 greater than at the KMY site. At similar milk production per cow it was €19 138 greater. Monte Carlo simulation showed that the MPN site was stochastically dominant over the KMY site. Sensitivity analyses showed that farm profit was most sensitive to changes in milk price. The results also indicated that milk production in the future may not be sustainable economically on high‐rainfall, heavy‐clay soils in Ireland.

Effect of Pregnancy on Milk Production and Bodyweight from Identical Twin Study

The energy requirements of the fetus through pregnancy have been previously investigated in several slaughter experiments, and many studies have attempted to estimate the effect of pregnancy on milk production. Data from 154 pasture-based dairy cows (77 twin pairs) were subjected to a retrospective analysis to determine the effect of pregnancy on milk production and body weight. A decline in milk yield from 126 d of pregnancy was observed in twins that were pregnant, but the decline was small and insignificant until 147 d of gestation (at 33 wk of lactation), after which pregnant cows produced less milk (0.8kg/cow per day). Protein and fat concentration increased in pregnant cows from 77 and 133 d of gestation, respectively. The yield of milk fat and protein was not affected by pregnancy until 168 d of gestation, after which pregnant cows produced less milk fat (0.06kg/cow per day) and milk protein (0.04kg/cow per day) compared with their nonpregnant twins. Body weight was higher in pregnant twin cows after 90 d of gestation and continued to increase until the end of lactation (182 d of pregnancy). Fitted splines showed higher milk protein concentrations in pregnant cows throughout lactation, and milk protein yield was higher (20g/cow per day) during the breeding season (between 12 to 17wk of lactation) in pregnant twins. Higher milk yield and energy secreted in milk (net energy for lactation) were also found in the pregnant twins during the breeding season. Although pregnancy-related reductions in yields of milk, milk fat, and milk protein occurred after midgestation, overall effects of pregnancy on milk production in this pasture-based, seasonal calving system were small.

The relationship between genetic merit for yield and live weight, condition score, and energy balance of spring calving Holstein-Friesian dairy cows on grass based systems of milk production

AbstractThe objective of this study was to estimate the effects of genetic merit for milk yield on energy balance (EB), dry matter intake (DMI), and fertility for cows managed on three different grass based feeding systems, and to estimate possible interactions between genetic merit and feeding system. Individual animal intake estimates were obtained at pasture on 11 occasions across three grazing seasons. The data set contained 96 first lactation animals in 1995, 96 second lactation animals in 1996, and 72 third lactation animals in 1997. Half of these animals were of high (HG), and half of medium genetic merit (MG) for milk solids production. Genetic effects for the traits of interest were estimated as the contrast between the two genetic groups, and by the genetic regression of phenotypic performance on the estimated breeding value for fat and protein yield, based on pedigree information alone (PI). Significant effects of feeding system were observed on yields, DMI and EB, whereas there was no effect on live weight, condition score or reproductive performance. The interaction between genetic merit and feeding system was not significantly different from zero for any of the traits. Yields, grass DMI, and total DMI were all higher for HG than for MG, and also positively correlated (P<0.001) with PI. Furthermore, condition score, conception to first and second service, and pregnancy rate were significantly negatively correlated with PI. While at pasture, EB was positively (P<0.01) correlated with PI, although the contrast between HG and MG was not significantly different from zero. Condition score changes during very early lactation, demonstrated that HG had a more negative EB than MG. The results clearly illustrate the production potential of HG cows on grass based systems, however the reduced reproductive performance questions their suitability for seasonal calving systems.

Embryo survival rate in cattle: a major limitation to the achievement of high fertility

AbstractOver the past 30-40 years genetic improvement and better nutrition of dairy cows have led to a significant increase in milk production per cow but this is associated with an increase in cow reproductive wastage. Reproductive wastage in the dairy herd particularly in a seasonal calving system, results in a serious financial loss. Early embryo death accounts for a significant portion of cow reproductive wastage and information is becoming available on the extent and timing of early embryo loss and on aspects of embryo growth, development, metabolism and viability. Such information is necessary to facilitate objective investigation of factors that contribute to early embryo death. For heifers and moderate yielding dairy cows published estimates of fertilisation rate of about 90%, and of average calving rates of about 55% indicate an embryonic and foetal mortality rate of about 40%. Of this total loss, 70 to 80% is sustained between days 8 and 16 after insemination, a further 10% between days 16 and 42 and a further 5-8% between day 42 and term. In high yielding cows there is some evidence of a higher increment of late embryo loss. During the period of greatest embryo loss, between days 8 and 16 after fertilisation, there is a dramatic increase in the growth rate and protein content of embryos, particularly from day 13 to day 16 when the increase is exponential. There is evidence that from day 13 to 15 cattle embryos undergo time and developmental stage-dependent changes in the rate of de-novo protein synthesis and protein phosphorylation. It seems that by the time cattle embryos have elongated they have passed their maximal synthetic activity in terms of protein synthesis and phosphorylation, which seems to occur at day 13 or earlier. While there is little published information on the causes of embryo loss it is clear that even a short-term reduction in energy intake near the time of insemination can significantly reduce embryo survival rate. Abo and low post-ovulatory systemic progesterone has been associated with increased embryo loss. Recent evidence shows that elevated systemic concentrations of ammonia and urea per se do not reduce embryo survival rate but there may be other modifying factors, such as negative energy balance, operating in the high yielding dairy cow that lead to reduced fertility when the systemic concentrations of urea and or, ammonia are high.

The Relationship Between Genetic Merit for Yield and Live Weight, Condition Score, and Energy Balance of Spring Calving Holstein Friesian Dairy Cows on Grass Based Systems of Milk Production

Objectives of this study were to estimate the effects of genetic merit for milk yield on energy balance, DM intake (DMI), and fertility for cows managed on three different grass-based feeding systems and to estimate possible interactions between genetic merit and feeding system. Individual animal intake estimates were obtained at pasture on 11 occasions across three grazing seasons. The data set contained 96 first lactation, 96second lactation, and 72 third lactation cows in 1995, 1996, and 1997, respectively. Half of these cows were of high genetic merit, and half were of medium genetic merit for milk solids production. Genetic effects for the traits of interest were estimated as the contrast between the two genetic groups and by the genetic regression of phenotypic performance on the estimated breeding value for fat and protein yield, based on pedigree index. Significant effects of feeding system were observed on yields, DMI, and energy balance, with no effect on live weight, condition score, or reproductive performance. The interaction between genetic merit and feeding system was not significantly different from zero for any of the traits. Yields, grass DMI, and total DMI were all higher for cows of high genetic merit than for those of medium genetic merit and were positively correlated (P<0.001) with pedigree index. Furthermore, condition score, conception to first and second services, and pregnancy rate were significantly negatively correlated with pedigree index. While at pasture, energy balance was positively (P<0.01) correlated with pedigree index, although the contrast between high genetic merit and medium genetic merit was not significantly different from zero. This positive energy balance was unexpected and was probably due to the lactation stage that intake was measured. Condition score changes and energy balance measures on a small sub-group of the animals, while indoors offered a diet of silage and concentrates (n=33), demonstrated that high genetic merit had a more negative energy balance than did medium genetic merit. The results clearly illustrate the production potential of high genetic merit cows on grass-based systems. The reduced reproductive performance questions the suitability of high yield for seasonal calving systems.

A Simulation Model of an Automatic Milking System Applying Different Management Strategies

Abstract A simulation model to test different management strategies for using robotic or fully automatic milking on dairy farms was constructed. An automatic milking system (AMS) is any system that allows dairy cows to be milked on demand with little or no human interaction. Typically, it consists of a selection system to identify the cow, a holding area, milking stalls served by a robot and an automatic concentrate feeder. It is likely that an AMS will be commercially available in the UK soon and it is therefore timely to consider the use of systems within farm practice. In the UK, most herds spend half the year grazing and otherwise housed indoors. It is unlikely that farmers would accept a change to a fully housed system. Thus, the benefits and drawbacks of an AMS for fully housed, zero-grazed and manually fetched (from fields) systems need to be examined. A three-phase discrete simulation model of an AMS has been developed. It has been used to study the performance of systems under a range of management options, including voluntary presentation, manual batch presentation and a mixture of the two, and to analyse the effect of herd size, milk yield and calving pattern. The results show that block calving systems need 20% larger milking capacity for the parlour than all-year calving, and that the difference in capacity of the robot between high and low yielding herds is small. Approximately, 30 cows can be milked by each milking stall for all-year calving herds, with a possible 100 milkings per day despite closure of the parlour for 6 h each day. The capacity of the milking parlour is not increased if more than four stalls are attached to each robot.

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)

Comparison of crossbred cows containing various proportions of Brahman in spring or fall calving systems: II. Milk production.

Monthly estimates of 24-h milk yield were obtained on 160 spring-calving and 153 fall-calving crossbred cows containing various proportions (0, 1/4 or 1/2) of Brahman breeding, all bred to Limousin sires. Milk production was measured using weigh-suckle-weigh procedures. Interactions between crossbred group and season of calving were not significant. Across seasons, milk production rarely was affected by proportion of Brahman breeding; however, milk yield, averaged over six monthly measurements, was greater (P less than .10) for cows out of Hereford dams than for cows out of Angus dams. Averaged over six monthly measurements, estimated 24-h milk yield ranged from 5.3 kg for Hereford x Angus to 6.2 kg for Brahman x Hereford cows. Season of calving affected milk yield during the first and fourth measurement periods. Fall-calving cows produced more (P less than .01) milk during the first period whereas spring-calving cows produced more milk during the fourth period. Lactation patterns for the two seasons differed. Spring-calving cows had a more typical lactation curve, whereas the curve for fall-calving cows showed more variability in milk yield throughout lactation. Phenotypic correlations between monthly measurements of 24-h milk yield and calf performance tended to be moderate and positive within the spring group. Correlations for the fall group, although positive, tended to be weaker than those found in the spring group.

Comparison of crossbred cows containing various proportions of Brahman in spring or fall calving systems. I. Productivity as two-year-olds.

Productivity of 2-yr-old crossbred cows containing various proportions (0, 1/4 or 1/2) of Brahman breeding was evaluated using 203 spring-calving and 171 fall-calving heifers over a 3-yr period. All heifers were mated to Limousin sires. Percentage of cows exposed to breeding that weaned a calf was the only trait for which a significant crossbred cow group x season of calving interaction was found. Preweaning ADG and age-adjusted weaning weight increased as proportion Brahman breeding increased. Age-adjusted weaning weight was similar for the two groups because 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. For weaning condition scores, an interaction between dam breed and proportion Brahman was detected; scores tended to be greater for calves out of 1/2 Hereford dams than for those out of 1/2 Angus dams, and this difference increased as proportion Brahman increased. Weaning conformation scores were similar for all calves. Age-adjusted weaning hip height increased as proportion Brahman breeding increased. Based on numbers of weaned calves, spring calving was more advantageous than fall calving. Averaged across both calving seasons, weaning weight tended to increase as proportion Brahman increased.

Effect of age at first calving and milking system on the lactation performance of F1 Bos indicus/Bos taurus crossbreds in Sabah.

This paper examines the effect of age at first calving and milking system on the overall lactation performance and incidence of lactation failure of 442 F1 Bos indicus/Bos taurus dairy crossbreds in Sabah. The two types of crossbred used in the study were imported F1 Sahiwal x Friesian and locally bred Friesian x Local Indian Dairy. Heifers which did not lactate for at least 120 days or produced less than 20 kg of milk during the fourteenth week of lactation were considered to have failed to establish a lactation. The imported and locally bred heifers recorded failure rates of 23.4 and 21.4% respectively. Three milking systems were examined namely machine milking without calf, machine milking with calf and hand milking. They produced failure rates of 30, 12 and 5.6% respectively. The cows that passed recorded 120 day milk production figures of 878, 1,134 and 1,054 kg respectively. The three age groups of less than 30 months, 30 to 34 months and greater than 34 months recorded failure rates of 37, 22 and 10% respectively. The heifers machine milked without their calf which calved at less than 30 months of age recorded a failure rate of 44% while those which calved at greater than 34 months recorded a failure rate of only 17%.

Feed additives for replacement heifer calves

In a 2 year calving system, growth rates of at least 0.65 kg/d are required in the first winter, preferably at only moderate concentrate input levels. One potential method of increasing feed efficiency and reducing costs is to use feed additives. A trial was carried out to examine the use of two feed additives as supplements for heifer calves offered silage and concentrates.