Genetic profile of total body energy content of Holstein cows in the first three lactations

Weekly total body energy content (TBEC) was calculated for 444 Holstein cows in their first 3 lactations. These calculations were based on body lipid and protein changes predicted from weekly changes in body condition score and live weight of each cow. In first lactation, cows lost TBEC during the initial 8 wk, regained it by wk 22, and continued to build up their reserves until wk 37. Cows started lactations 2 and 3 with considerable reserves from the dry period that they used during the first 13 wk of lactation. Variance components for TBEC were estimated using random regression analysis allowing for heterogeneous residual variance. The genetic variance increased within each lactation, suggesting that the genetic component becomes more important as lactation progresses. The genetic correlations between very early ( wk 1 to 4) and later stages of first lactation were near zero but they increased considerably between later lactation stages. Genetic correlations between TBEC on wk 5 of first lactation and the remainder of this lactation ranged from 0.64 for the more distant weeks to 0.99 for the immediately subsequent weeks. Genetic correlations with TBEC in second lactation were moderately high (0.68 to 0.70) for the early weeks ( 1 to 8) and decreased gradually to 0.56 for weeks at the end of lactation. For third lactation, these estimates ranged from 0.53 to 0.63. Genetic correlation estimates of TBEC in wk 12 of first lactation with subsequent first-lactation weeks varied from 0.79 to 0.99, whereas they ranged from 0.65 to 0.77 and from 0.57 to 0.68 in second and third lactations, respectively. The genetic correlation between TBEC in later weeks of first lactation and the rest of productive life increased as first lactation progressed, but the improvement diminished. Weekly genetic evaluations for first-lactation TBEC were used to predict second- and third-lactation energy content. The accuracy of these predictions increased with progressing weeks in first lactation, but about three-fourths of the improvement occurred by wk 5. Our results suggest that TBEC calculated after a month from the first calving may give useful information about the future energy content of a cow.</p

Feed intake and weight and body condition changes of 100% organically fed lactating sows

Energy and protein density of the 100 % organic lactation diet should be increased as early as from 3rd week of lactation onwards in order to minimize the weight loss of the sow during the at least 40 day lactation period. Feed amino acid balance from 22nd day of lactation should match the amount of live weight lost during the first 21 days of lactation. This should be supported by providing the piglets feed attractive enough to ensure their high dry feed intake during the late lactation period

Maternal zinc intakes and homeostatic adjustments during pregnancy and lactation.

Zinc plays critical roles during embryogenesis, fetal growth, and milk secretion, which increase the zinc need for pregnancy and lactation. Increased needs can be met by increasing the dietary zinc intake, along with making homeostatic adjustments in zinc utilization. Potential homeostatic adjustments include changes in circulating zinc, increased zinc absorption, decreased zinc losses, and changes in whole body zinc kinetics. Although severe zinc deficiency during pregnancy has devastating effects, systematic reviews and meta-analysis of the effect of maternal zinc supplementation on pregnancy outcomes have consistently shown a limited benefit. We hypothesize, therefore, that zinc homeostatic adjustments during pregnancy and lactation improve zinc utilization sufficiently to provide the increased zinc needs in these stages and, therefore, mitigate immediate detrimental effects due to a low zinc intake. The specific questions addressed are the following: How is zinc utilization altered during pregnancy and lactation? Are those homeostatic adjustments influenced by maternal zinc status, dietary zinc, or zinc supplementation? These questions are addressed by critically reviewing results from published human studies on zinc homeostasis during pregnancy and lactation carried out in different populations worldwide

Differential leukocyte count method for bovine low somatic cell count milk

Whereas many differential leukocyte count methods for high somatic cell count (SCC) milk from mastitic cows are available, only a few have been developed for low SCC milk. We have developed a flow cytometric differential leukocyte count method for low SCC milk. The procedure consists of 1) 1.5 ml of diluted milk sample (30%, vol/vol dilution with PBS), 2) centrifugation, 3) leukocyte labeling with SYTO 13 and 4) flow cytometric analysis. Four major leukocyte populations can be clearly identified in the green fluorescence-side scatter dot plot: lymphocytes and monocytes (LM), polymorphonuclear neutrophils (PMN), mature macrophages (MO), and cells with apoptotic features based on chromatin condensation and nuclear fragmentation. The optimal processing temperature was 20degreesC. Significant differences among samples with similar differential leukocyte counts were found. Storage of milk samples during 2 d at 7degreesC had no effect on differential leukocyte count. Using the new method, differential leukocyte count was performed in low SCC milk samples from cows in early, mid, and late lactation. In accordance with previous studies, PMN and M P percentages were lower and LM percentages were higher in early lactation than in the other stages of lactation. The percentage of cells with apoptotic features was higher in early lactation than in mid and late lactation. In conclusion, a rapid, simple, accurate, and reproducible standard procedure was developed to determine the differential leukocyte count (MO, PMN, LM, and cells with apoptotic features) of bovine low SCC milk

Organic dairy cows: milk yield and lactation characteristics in thirteen established herds and development of a herd simulation model for organic milk production

As a consequence of organic standards and principles, organic dairy producers are frequently faced with a different set of management considerations than those found in conventional dairy systems. The broad objective of this study was to examine in detail the production characteristics of 13 well-established organic dairy herds, and to relate these to the specific conditions that exist within organic dairy farming. Monthly milk records for 13 organic herds for three years were collected and converted into a Microsoft Access database, using InterHerd™ (Agrisoft Plc., UK) herd management software. The data were sorted and analysed using the InterHerd-herd management, Excel for Windows™ and Statistix for Windows software programmes. Estimated parameters were used to examine the importance of two important indicators: lifetime yield/lactation length and economic efficiency. To assess the first, a spreadsheet model based on the Wood's lactation curve was developed. With regard to the latter, a model calculator was used. Five herds were chosen for case studies, that examined the farm performance by using InterHerd™-generated data and by interviewing the producer retrospectively and asking him to comment on the data. Results Milk yield and lactation characteristics The 13 established, organic herds were characterised with relatively low yields, but herd variation was great: from a total lactation yield of 5,100 kg to 7,000 kg. Milk fat and protein content, lactation length and individual cow SCC means were similar to those reported in conventional, milk recorded herds. Lactation yields increased up to the third lactation, whereas persistency of lactations decreased up to the third lactation. This pattern followed similar patterns reported in conventionally managed herds. Similarly, somatic cell counts increased with parity, mimicking similar phenomenon reported in conventionally managed dairy cows. Length of lactation and lactation persistency were associated with month of calving, with autumn calving cows tending to have shorter lactations with better persistency. This phenomenon was, however, confounded with parity. Fertility It is concluded that fertility performance in terms of culling for fertility and mean calving intervals were better in the organic survey herds when compared with existing data from conventionally managed UK dairy herds. Good fertility performance even in the highest yielding organically managed cows suggests that early lactation energy deficit may not be a major problem in these herds. It is also suggested that financial impact of high number of services per conception, as observed in majority of the survey herds, may be insignificant as the main losses caused by poor fertility are attributable to culling and prolonged calving intervals. Herd models Herd productivity indices were generated, using an existing model based on a measure of feed conversion efficiency at the herd level. The advantage of using this approach in the estimation of productivity is that it takes full account of the entire feed input to the system, including forage. The production index was closely and independently associated with yield and calving rate. Culling was not independently associated with the production index but once calving rate and lactation yield are taken into account, culling rate also becomes a significant factor. Case studies Case studies demonstrated the usefulness of recorded data analysis, using herd management software and observation of seasonally adjusted lactation curves to examine feeding management. In all five herds, apparent and reoccurring seasonal feeding and grazing management shortcomings were detected. Recommendations Further research would need to be carried out to establish financial consequences of poor fertility in organic systems with different milk pricing and cow values. Similarly, further research is needed to establish causes for high numbers of services per conception in these herds and to establish whether this phenomenon exists in other organically managed herds. The herd productivity calculator model (LPEC) showed to be a good and robust measure of productivity. Next logical step in this analysis would be to gain data on purchased feeds, so that the productivity index can be expressed in terms of a gross margin per unit of forage input. This would allow the full importance of forage to organic dairy systems to be expressed, and would also allow productivity to be evaluated in terms economic margin per unit of input produced on-farm. The LPEC generated indices could also be utilised to examine the potential impact of changes to systems before an intervention is implemented, by including costs of intervention and assumed values of production post-intervention. Sensitivity analyses may be conducted to identify the relative importance of individual production parameters to overall herd productivity. Careful assessment of lactation characteristics in a herd is needed to predict the overall impact of extended calving intervals. It is likely that in most organic herds feeding management would need to be adjusted in order to produce lactations with low late lactation decline to avoid financial losses caused by longer calving intervals. Analysis of seasonally adjusted lactation curves as a monitoring and decision support system for feeding management is likely to be a useful for organic herds, particularly during conversion period when new feeding systems need to be introduced in a herd

Milk production and survival of spring-calving carryover cows in New Zealand dairy herds : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Manawatu, New Zealand

Non-pregnant cows are generally culled from dairy herds and replaced with two-year-old heifers. Alternatively, non-pregnant cows can be dried-off at the end of lactation, retained for one year (carried over), before being mated and returned to a milking herd in the following year. In this study, calving interval was used as a tool to identify and define the carryover cow population in spring-calving dairy herds. Linear modelling methods were used to compare carryover cow milk production with that of heifers, lactation-matched and age-matched non-carryover cows. Lastly, the survival for second-lactation carryover cows was compared with that of two-year-old heifers and lactation-matched non-carryover cows. Results showed that annually, 2.5% of spring-calving cows had returned to a milking herd after a carryover period in the previous year. Of those carryover cows, 43% returned to a milking herd at four years old, after failing to conceive in their first lactation. Most (69%) dairy herds contained less than 5% carryover cows and 17% of dairy herds comprised of zero carryover cows. The difference between the proportion of Holstein-Friesian in the carryover cow and non-carryover cow group was minimal (2%) but statistically greater (P<0.01) for the carryover cow group. Estimated breeding values (EBVs) for milk traits (milk yield, fat yield, protein yield and somatic cell count) were greater (P<0.01), but fertility EBVs were lower (P<0.01) for the carryover cow group in the year when they failed to conceive, compared to those for the non-carryover cow group. These were reflected in greater (P<0.01) selection indices (Breeding Worth and Production Worth) for carryover cows. After the carryover period, EBVs for milk traits and fertility decreased, and Breeding Worth was lower (P<0.01) for the carryover cow group, compared to the non-carryover cow group. Carryover cow milk yield, fat yield, protein yield and somatic cell score was greater (P<0.01) than those for heifers, lactation-matched and age-matched non-carryover cows in their first carryover year. This milk production advantage was maintained for up to three carryover years, if the carryover cow maintained an annual calving pattern, but at a decreasing rate. The probability of survival (days) was lower (P<0.01) for second-lactation carryover cows when compared to heifers and lactation-matched non-carryover cows. These findings are important for the New Zealand dairy industry as they can aid on-farm culling (removal from the herd) decisions

Energy Consumption of Lactating Mothers: Current Situation and Problems

Recommendations on the adequacy of nutrient intake indicate that lactating mothers have higher nutritional needs than do pregnant mothers. High nutrient intake is necessary to help mothers recover after childbirth, produce milk, and maintain the quantity and quality of breast milk. It also prevents maternal malnutrition. Research has shown, however, that the dietary energy consumption of mothers during lactation was significantly lower than that during pregnancy. The current study explored the factors associated with decreased nutritional intake during maternal lactation. The study was conducted in March&ndash;April 2013, and the subjects were mothers with infants aged &gt;6 months. Results revealed that the factors causing low dietary energy consumption among breastfeeding mothers were poor nutritional knowledge and attitude toward high energy intake requirements during lactation, lack of time to cook and eat because of infant care, reduced consumption of milk and supplements, dietary restrictions and prohibitions, and suboptimal advice from midwives/health personnel. Beginning from the antenatal care visit, health personnel should conduct effective counseling on the importance of nutrient intake during lactation. Advice should be provided not only to mothers, but also to their families to enable them to thoroughly support the mothers as they breastfeed their infants

Genetic Relationship of Body Energy and Blood Metabolites with Reproduction in Holstein Cows

Body condition score (BCS), energy content (EC), cumulative effective energy balance (CEEB), and blood serum concentrations of glucose, beta-hydroxybutyrate (BHBA), and nonesterified fatty acids ( NEFA) were measured throughout first lactation in 497 Holstein cows raised on a large commercial farm in northern Greece. All these traits are considered to be indicators of a cow's energy balance. An additional measure of BCS, EC, and blood serum glucose, BHBA, and NEFA concentrations were taken approximately 2 mo (61 +/- 23 d) before first calving. During first lactation, first service conception rate, conception rate in the first 305 d of lactation, interval from calving to conception, number of inseminations per conception, incidence of metritis, and incidence of reproductive problems of these cows were recorded; interval between first and second calving, and second lactation first service conception rate were also recorded. Random regression models were used to calculate weekly animal breeding values for first lactation BCS, EC, CEEB, glucose, BHBA, and NEFA. Single trait animal models were used to calculate breeding values for these traits measured on pregnant heifers before calving. Reproductive records were then regressed on animal breeding values for these energy balance-related traits to derive estimates of their genetic correlations. Several significant estimates were obtained. In general, traits that are known to be positively correlated with energy balance (BCS, EC, CEEB, and glucose) were found to have a favorable genetic relationship with reproduction, meaning that increased levels of the former will lead to an enhancement of the latter. On the other hand, traits known to be negatively correlated with energy balance (BHBA and NEFA) were found to have an unfavorable genetic association with reproductive traits. Body condition score, BHBA, and NEFA recorded early in lactation, and glucose concentrations measured in pregnant heifers had the highest genetic correlation with future reproductive performance. Results suggest that genetic selection for body energy and blood metabolites could facilitate the genetic improvement of fertility and overall reproductive efficiency of dairy cows.</p

Effects of stage of lactation and time of year on plasmin-derived proteolytic activity in bovine milk in New Zealand

The objective of this study was to determine the effects of stage of lactation (SOL) and time of year on plasmin-derived proteolytic activity in the milk of pasture-fed dairy cows in New Zealand. Four herds of 20 Friesian cows were used, one herd calving in each of January, April, July and October. Cows grazed ryegrass/white clover pasture only, except during June (winter) when all cows received supplementary pasture silage. Milk samples were collected on four occasions during the year (spring, summer, autumn and winter) from each cow in milk, to give a total of three samples per cow (early, mid and late lactation; c. 30, 120 and 220 days after calving, respectively). Milk samples were analysed for plasmin-derived proteolytic activity. There was no effect of either SOL or time of year on plasmin activity and therefore yields of plasmin followed patterns in milk yield (highest in early lactation and in summer). There were effects of both SOL and time of year on plasminogen-derived and total plasmin plus plasminogen-derived activity, both of which were highest in late lactation and in spring. Changes in plasminogen-derived activity and total plasmin plus plasminogen-derived activity due to SOL were not only due to the decrease in milk yield associated with advancing lactation, because enzyme yields were also increased with advancing lactation. Similarly, effects of time of year on plasminogen-derived activity and total plasmin plus plasminogen-derived activity could not be attributed solely to concomitant changes in milk yield, and may be influenced by the variation in the quality and quantity of feed during the year inherent in a pasture-based dairy system. Effects of SOL on proteolytic activity were greater than, and independent of, effects of time of year