Dual-purpose Herds Research Articles

Comparative productive performance of cows born through embryo transfer, artificial insemination and natural mating in dairy and dual-purpose herds raised in tropical conditions.

A populational, observational and longitudinal-retrospective study with records of 28 dairy specialized and dual-purpose farms, was carried out to compare the productive performance of cows born by embryo transfer (ET), artificial insemination (AI), and natural mating (NM), using the database of Centro Regional de Investigación para la Producción Animal Sostenible (CRIPAS) of cattle herds in Costa Rica. Herds (system × altitude), conception method (ET, AI and NM), genetic background (DSpB: specialized dairy breeds (Bos taurus) and crosses, GYR×HOL: Gyr × Holstein Crossbred and DSpB×BI: crosses between dairy breeds and Bos indicus), year of birth (or at calving), lactation number and days in milk were evaluated for the productive parameters age at first calving (AFC), calving to conception interval (CCI) and lactation milk yield (LMY) using a GLIMMIX procedure on SAS. The AFC, CCI, and LMY were affected (P<0.0001) by all factors considered in each parameter. ET has lower (P<0.0001) AFC in months (33.1) than AI (35.2) and NM (36.44). NM had lower (P=0.004) CCI (110 d) than AI or ET (121 d) values which were similar (P>0.05). The higher LMY (P<0.0001) was observed in ET (4140 kg), compared to AI (3706 kg) and NM (3595 kg). There was no difference between AI and NM. In conclusion, the method of conception in calves affected their future reproduction and production during puberty, postpartum, and lactation. The effects on management decisions will require a rigorous economical study to discern whether ET would be a cost-effective alternative to AI or NM.

La inflamación uterina de la vaca postparto. Del dicho al hecho…

Reproductive efficiency is one of the most important factors determining the genetic progress and productivity of cattle herds. To maintain acceptable reproductive efficiency, it is necessary for cows to have a calving interval of less than 400 days; a calving-conception interval of less than 110 days and less than 3 services per conception. Reproductive efficiency largely depends on the health and fertility of the herd. Postpartum uterine inflammation (metritis/endometritis/pyometra) is one of the main causes of poor reproductive performance in dairy and dual purpose herds. This condition results in low pregnancy rates, high number of services per conception, long postpartum intervals, high culling rates, and substantial economic losses (Gilbert et al., 2016). There is a great discrepancy in the criteria for diagnosis and treatment of puerperal metritis in dairy farms. In the case of endometritis, the situation is even more critical, because diagnosis is not routinely carried out at the field level, which limits the timely establishment of treatments and preventive management measures.

Carbon footprint and mitigation strategies among heterogeneous dairy farms in Paraná, Brazil

Dairy production is a vital part of the Brazilian agri-food system, providing food security, employment, and income in rural areas. Nevertheless, rearing dairy cattle leads to greenhouse gases (GHG) emissions which may contribute to global warming and consequently climate change. The remarkable heterogeneity among dairy farms as well as the lack of representative research pose constraints to the development of effective actions to reduce GHG emissions in emerging countries. In this study, we explore a large farm survey to group farms and derive their carbon footprint (CF). Cluster analysis and life cycle assessment are applied to a sample of 911 farms. The results of the analysis categorized the farms into four groups. Statistical comparisons indicated a significant difference in the CF between groups for producing one kg of fat and protein corrected milk (FPCM). The mean CF results ranged from 1.75 kg CO2eq. (kg FPCM)−1 in Group 1 (G1) to 3.27 kg CO2eq. (kg FPCM)−1 in Group 4 (G4). While G1 was composed of larger farms, on average having more access to technologies and technical support, G4 was composed of less specialized producers, owning dual-purpose herds. We also identified and discussed key strategies and management practices that can be adopted by farmers for reducing the CF of dairy farming. Research and policy should strive to accelerate farmers’ adoption of intensification technologies and practices, though following sustainable intensification practices that also account for regional socioeconomic development.

Seroprevalence of Major Pasture-Borne Parasitoses (Gastrointestinal Nematodes, Liver Flukes and Lungworms) in German Dairy Cattle Herds, Association with Management Factors and Impact on Production Parameters.

Simple SummaryPasture-borne worm infections impact cattle health and productivity worldwide. The present study assessed exposure of dairy cattle herds to the three most important pastural parasites, i.e., gastrointestinal worms, liver flukes and lungworms, in three parts of Germany by measuring antibodies in bulk tank milk samples. The results show a high level of exposure to gastrointestinal worms, while antibodies against liver flukes were less frequently detected and lungworm-positive herds were rare. Regional and breed differences regarding parasite exposure were detected. In addition, the presence of antibodies was associated with access to fresh grass, access to hay, silage quality and deworming frequency. Furthermore, parasite exposure was significantly associated with a poor body condition across all regions. Parasite-exposed cows of high-performance breeds also produced on average less milk per year than dual-purpose breeds. Pasture-borne parasites adversely affect bovine health and productivity worldwide. In Europe, gastrointestinal nematodes, especially Ostertagia ostertagi, the liver fluke Fasciola hepatica and the lungworm Dictyocaulus viviparus represent the most important parasites of dairy cattle. The present study assessed exposure towards these parasites among 646 cattle herds in three parts of Germany during 2017–2019 via antibody detection in bulk tank milk (BTM). Overall, O. ostertagi levels indicative of production losses were detected in 41.2% (266/646; 95% confidence interval (CI): 37.4–45.1%) of BTM samples, while F. hepatica seroprevalence amounted to 14.9% (96/646; 95% CI: 12.2–17.9%). Only 2.3% (15/646; 95% CI: 1.4–3.9%) of samples were D. viviparus antibody-positive. Significantly lower O. ostertagi as well as F. hepatica seroprevalence was detected in dual-purpose breeds compared to high-performance breeds from the same region. Management factors related to parasite exposure included access to fresh grass and hay, silage quality and anthelmintic treatment. Furthermore, F. hepatica and O. ostertagi seropositivity was significantly associated with suboptimal herd-level body condition. Interestingly, the relationship between seropositivity and productivity differed between breed types. Negative impacts on milk yield were detected only in high-performance breeds, while O. ostertagi seropositivity was associated with a lower milk fat content in dual-purpose herds.

Seroprevalence and risk factor associated with respiratory viral pathogens in dual-purpose cattle of Aguachica, Rio de Oro, and La Gloria municipalities in Cesar department, Colombia.

Aim:The research was conducted to determine the seroprevalence and risk factor associated with respiratory viral pathogens in dual-purpose cattle of Aguachica, Rio de Oro and La Gloria municipalities in Cesar department, Colombia.Materials and Methods:The seroprevalence study was done from the random sampling (n=1000) of blood collected from 29 dual-purpose herds, located in three municipalities (Aguachica, Rio de Oro, and La Gloria) of Cesar department. The presence of antibodies against bovine herpesvirus type 1 (BHV-1), bovine respiratory syncytial virus (BRSV), bovine viral diarrhea virus (BVDV), and bovine parainfluenza-3 virus (BPI-3V) in the samples was detected by indirect enzyme-linked immunosorbent assay. Epidemiological data were obtained using a questionnaire administered to the owner or manager of each herd.Results:The overall highest seroprevalence was observed for BHV-1 (94.7%), followed by BRSV (98.6%), BVDV (35.2%), and BPI-3V (47.1%). Regarding the seroprevalence by municipalities, there was a statistical association (p<0.05) for BVDV; however, for BRSV, BHV-1, and BPI-3V, no statistical association was found (p>0.05) between seropositive values and the municipalities, indicating that animal was seropositive in similar proportions in the three municipalities. Female sex and older animals (>24 months) were a significant risk factor for BHV-1 and BPI-3V infection. Regarding the clinical signs, there was a statistical association (p<0.05) between the seropositive values of BVDV and most of clinical signs observed, except for abortion.Conclusion:This research confirms the high seroprevalence of the respiratory viral pathogens in nonvaccinated cattle within the study areas. Therefore, appropriate sanitary management practices and routine vaccination programs should be adopted to reduce the seroprevalence of these infectious agents.

Prevalence and herd-level risk factors of bovine tuberculosis in the State of Goiás, Brazil

Bovine tuberculosis results in economic losses in livestock production and poses a risk to public health. This study aimed to characterize the epidemiological status of bovine tuberculosis in adult cows in the state of Goiás, Brazil. The state was divided into three sampling strata, corresponding to different livestock production circuits. A total of 18,659 animals were tested with the comparative cervical tuberculin test (CCT), in 300 randomly sampled bovine herds per stratum. An epidemiological questionnaire was used to identify health and management practices that may be associated with the presence of tuberculosis infection in the herd. In Stratum 1, dominated by beef cattle, no animals reacted to the CCT. In Stratum 2, which covers the main dairy regions of the state, the prevalence was estimated at 8.67% [5.73 to 12.74%] for herds and at 0.9% [0.21 to 1.58%] for animals. In Stratum 3, characterized by a mix of dairy, beef and dual-purpose herds, the prevalence was estimated at 1.00% [0.21 to 2.89] for herds and 0.30% [0.10 to 0.49 %] for animals. The overall prevalence in the state of Goiás was 3.43% [2.20 to 4.67%] for herds and 0.30% [0.10 to 0.49%] for animals. The multiple logistic regression analysis revealed that herd-level risk factors associated with the presence of the bovine tuberculosis are: the location of the herd in Stratum 2 (OR = 12.05 [3.52 to 41.28]) and the number of times a cow is milked per day (OR = 6.27 [2.72 to 14.44]). Regular veterinary care was identified as a protective factor (OR = 0.38 [0.15-0.94]). These results indicate that bovine tuberculosis is endemic in the state; its spatial distribution is heterogeneous with a strong concentration in dairy regions. The most intensive dairy farms are those with the highest risk, which is consistent with what other authors’ found elsewhere in Brazil. The epidemiological information generated by this study provides information for planning of risk-based surveillance actions, and justifies the adoption of free-herd certification programs for bovine tuberculosis in the main dairy regions of Goiás.

Prevalence and herd-level risk factors of bovine tuberculosis in the State of Santa Catarina

With the aim of supporting the strategic planning of the National Program for Control and Eradication of Brucellosis and Tuberculosis, different Brazilian states have been conducting cross-sectional studies, coordinated by the Ministry of Agriculture, Livestock, and Supply and with scientific support from the University of São Paulo and the University of Brasilia. In Santa Catarina, the State Animal Health Agency (CIDASC) conducted a study on bovine tuberculosis (TB) prevalence and assessment of risk factors in 2012. The state was divided into five regions and, in each region, independent sampling was performed in two steps: (i) cattle herds with reproductive activity were randomly selected; and (ii) in each herd, a sample of females aged 24 months or older underwent the intradermal comparative tuberculin test. A questionnaire was used to collect data on production characteristics and management practices that could be associated with the tuberculosis infection. Herd prevalence of bovine TB was 0.50% (95% confidence interval [CI]: 0.074–0.93%) while the prevalence of TB in adult females was 0.06% (95% CI: 0–0.12%). No significant difference in the prevalence of infected herds and of positive females was observed among the five regions. The logistic regression model revealed that herds with 19 or more females showed an odds ratio (OR) of 7.68 (95% CI: 1.22–48.39) compared to smaller herds, while dairy herds presented an OR of 10.43 (95% CI: 2.00–54.25) relative to beef or dual-purpose herds. The results suggest that dairy herds, in which animals are kept in partial or total confinement, and larger herds, which tend to acquire animals more often, are at a higher risk of bovine TB. Given the low prevalence and the type of higher-risk properties, a bovine TB surveillance system should be targeted at the state’s dairy basins, particularly the western region that accounts for the major industries and more intensive dairy farms.

Eficiencia técnica en hatos lecheros en Costa Rica.

The objective of this work was to quantify technical efficiency in 1086 dairy farms from Costa Rica (year 2007) using Stochastic Frontier Analysis. The base model analyzed the endogenous variable logarithm of Milk Solids (kg/ha/week) as a function of 14 different predictive variables related to physical and management aspects. Overall mean for milk solids was 32.5±23.5 kg, with the highest mean for typology of Specialized Intensive Dairy Herds from the Highlands (83.9 kg), followed by Intensive Dairy Herds from the Lowlands (51.0 kg), Semi-Intensive Dairy Herds from the Highlands (33.8 kg), Extensive Dairy Herds from the Lowlands (23.0 kg) and Dual Purpose Herds from the Lowlands (8.5 kg). Variables associated (P<0,001) to milk solids were stocking rate, fertilizer application, concentrate feeding, proportion of cattle from specialized dairy breed, altitude and grazing area. An increase of 1% in these variables was associated with a change of 0,85%, 0,07%, 0,07%, 0,19%, 0,15% and -0,10% in milk solids, respectively. Overall technical efficiency was 0,75±0,09. When farm typology was added as a predictor into the model, efficiency increased to 0,79±0,07, whereas adjusting the model separately for each farm typology resulted in an overall efficiency of 0,77±0,11. The latter was preferred because better reflects heterogeneous elasticity of predictive variables between different typologies.

History, structure, and genetic diversity of Brazilian Gir cattle

The Gir cattle breed (Bos indicus) is an important genetic resource for milk production throughout the tropics. The small number of Gir animals introduced in Brazil, rapid dissemination of this breed recently, and the intensification of selection practices could contribute to increase of inbreeding level and reduce genetic diversity in this population. The population was analyzed in terms of pedigree completeness level, inbreeding coefficient, coancestry, generation interval, effective population size, effective number of founders and ancestors, among others. Despite the low mean inbreeding (around 2%), minor problems were identified in the population structure of the Brazilian Gir cattle, e.g., trend of narrower bottlenecks in the pedigree in recent years. The effective population sizes based on inbreeding (94) or coancestry (165.9) as well as the effective number of ancestors (76) and founders (143) were relativity high. The major subdivision of the Gir breed was observed between 1993 and 2002 (dairy and dual-purpose herds, wide use of within-herd matings). In this period the level of inbreeding remained at a higher level, there was a small increase in coancestry and the number of equivalent subpopulations was approximately 6. After 2002, there was genetic exchange between subpopulations, reduction in the average inbreeding, pronounced increase in the average coancestry, and the number of equivalent subpopulations was about 2. Furthermore, it was found that the mean generation interval of the population tended to increase in recent years (around 9 years). About 2.3% of genetic diversity has been lost since the first generation of founders. Based on the effective population size, number of equivalent subpopulations, inbreeding, coancestry, and loss of genetic diversity, the Gir population is still highly structured, but there is ample room for artificial selection. The results regarding the effective number of founders and ancestors in the present population demonstrate the existence of bottlenecks in the pedigree and indicate the need for population structure monitoring. Nevertheless, the Brazilian Gir breed can perfectly face a breeding program with high selection intensity.

Caracterización y clasificación de hatos lecheros en Costa Rica mediante análisis multivariado.

This study was carried out to characterize and classify a group of herds (n=1086) associated to the main Dairy Cooperative in Costa Rica. The information analyzed in this study was obtained initially from the last census conducted by the cooperative during year 2007. This information was complemented with computerized records of the same cooperative and geographical information systems with climatic and soil types data. Farm classification was performed by combining two different multivariate techniques: Factor Analysis (FA) and Cluster Analysis (CA). Analysis was performed on 18 variables, mainly related to physical and climatic aspects, herd management, input level and production level. FA identified three significant principal factors: intensification level, altitude (masl), and productive orientation accounting for 42,6%, 24,2% and 13,2% of total variance. On the basis of these three factors, CA identified five main herd typologies: Intensive specialized dairy herds in the highlands (n=374), Semi-intensive specialized dairy herds in the highlands (n=274), Intensive specialized dairy herds in the Lowlands (n=167), Extensive specialized dairy farms in the Lowlands (n=189) and Extensive Dual-Purpose herds in the Lowlands (n=82).

Efecto del genotipo sobre la producción láctea en vacas Europeo Lechero x Cebú de doble propósito

El objetivo de este trabajo fue evaluar el comportamiento productivo de grupos raciales cruzados 7/8 Holstein X1/8 Cebú (n= 112), 7/8 Suizo Americano X 1/8 Cebú (n=138) y 7/8 Simmental X1/8 Cebú (n=191) sobre la producción de leche y crecimiento de becerros. La información analizada se obtuvo de 341 vacas, procedentes de tres ganaderías de doble propósito en el Norte de Puebla; México. Las variables estudiadas incluyeron la producción de leche por lactancia (PTL), época de inicio de lactancia (EIL), días al pico de lactancia (PL), comportamiento de los becerros hasta el destete (CBD) y productividad económica. Los resultados obtenidos indicaron que la producción de leche por lactancia y los días en lactancia fueron afectados por el genotipo (P&lt;.01). Las variables productivas para el comportamiento hasta el destete de crías de vacas 7/8 Europeo lechero x 1/8 Cebú en doble propósito incluyeron; peso al nacimiento (PN), Peso al destete (PD), ganancia diaria de peso (GDP) y edad al destete (ED), se evaluaron por análisis de sobrevivencia. Los resultados indicaron que el grupo racial no influyó (P&gt; .01) en ninguna de las características productivas estudiadas. En conclusión, las vacas 7/8 Holstein x 1/8 Cebú (HC) y 7/8 Suizo Americano x 1/8 Cebú (SC) mostraron mayor habilidad productiva que las vacas con genes de simmental. Los resultados observados sugieren la posibilidad de usar los grupos raciales HC y SAC, como los más apropiados para la producción de leche en el norte de Puebla.

Detection of antibodies and risk factors for infection with bovine respiratory syncytial virus and parainfluenza virus 3 in dual-purpose farms in Colima, Mexico

A cross-sectional study was carried out, from November 2007 to March 2008, to estimate the prevalence of and to determine risk factors associated with bovine syncytial respiratory virus (BRSV) and parainfluenza 3 virus (PIV3) in dual-purpose herds in Colima, México. One hundred and seventy-six sera from 33 herds for PIV3 and 232 sera from 44 herds for BRSV were used. Sera were analyzed by indirect ELISA for the detection of antibodies against BRSV and PIV3 in cattle herds to determine the seroprevalence of respiratory diseases. The apparent and true prevalences for PIV3 were 60.8% and 54.4% and for BRSV 52.2% and 50.8%, respectively. The percentage of herds showing at least one positive animal was 78.7% for PIV3, and 93.2% for BRSV. Age (≤ 12, 13-48, and >48 months old) and respiratory signs (no, yes) showed significant association (P < 0.05) with PIV3 and age with BRSV. This study showed that animals were exposed to both viruses and that age was the main risk factor. The need to establish new vaccination plans to effectively protect cattle against those infections in the state of Colima, Mexico is suggested.

Prevalence of cattle herds with ivermectin resistant nematodes in the hot sub-humid tropics of Mexico

The objective was to determine the prevalence of semi-intensive Bos indicus and Bos indicus×Bos taurus cattle herds with ivermectin (IVM) resistant nematodes in a sub-humid tropical zone of Mexico using the faecal egg count reduction test (FECRT). Thirty-three herds (28 beef and 5 dual purpose herds) were monitored in a period of 6 months (September 2008 to February, 2009). Only 14 of the 33 herds were included in the trial. The other herds had not enough animals with sufficient nematode eggs per gram of faeces (EPG) to be included in a FECRT. Some farms were visited twice trying to find more animals with egg counts higher than 150 EPG. In the 14 surveyed herds the calves were randomly distributed into two groups: (a) treatment group received 0.2mg of IVM/kg BW sc on day 0, and (b) control group without treatment. Faecal samples were obtained from each animal on days 0 and 14 post-treatment. Reduction percentages (% R) and 95% CI were calculated. The prevalence of cattle herds with IVM resistant nematodes was 78.6%. Those suspected of IVM resistance were 21.4%. All surveyed herds used IVM from two to three times a year (mainly beginning and end of the wet season) during 1–11 consecutive years. The farm with stronger resistance used IVM for 11 consecutive years (% R=0%; 95% CI=0–47%). Genera of nematodes resistant to IVM were: Ostertagia, Haemonchus, Cooperia and Trichostrongylus. A considerable effort is needed to perform FECRT in cattle herds under hot sub-humid tropical conditions.

Supporting dairy farms by improving water productivity in the Tadla irrigation scheme (Morocco)

A research intervention was conducted in the dairy supply chain of the Tadla irrigation scheme in Morocco. The main objective was to assess water productivity through dual purpose herds (milk and meat) and to identify ways of improving it through better fodder yields and cattle rearing practices. An intervention method was tested. It relied on technical support for 10 cattle farmers. A regular evaluation of diets distributed to lactating cows was undertaken. In cases of nutritive insufficiencies or imbalances in relation to cows' potential milk yield requirements, an adequate supplementation was proposed and its effects on milk productivity assessed. In addition, a simulation tool was designed and tested with farmers to determine the effects of strategic changes (substitution of crossbreeds by pure Holstein cows, replacement of alfalfa by maize silage, introduction of drip irrigation) on their overall performance. The field study revealed that some 1.8 cubic meters of water were necessary for 1 kg of milk, whereas a volume of 10.6 cubic meters of water was needed for a kg of cattle live weight gain. The economic values of water productivity were 0.07 € and 0.24 € per cubic meter of water, respectively, for milk and live weight gain. The use of balanced diets made it possible to increase the average milk yield per cow. The results indicated that water productivity through irrigated cattle farming may be significantly improved by enhancing cropping and cattle rearing practices. This implies that on-farm extension services have to be improved to test such intervention tools at a larger scale.

Control of postpartum anestrous with an intra-vaginal progesterone device plus eCG or calf removal for 120 h in suckled crossbred cows managed in a pasture-based system

To control postpartum anestrus and reduce calving to conception interval, 167 crossbred non-pregnant cows that were 90–130 days postpartum were allotted randomly to one of the following treatments: PH ( n = 59), intra-vaginal sponge with 250 mg of medroxyprogesterone acetate (MAP) for 7 days plus 50 mg of MAP and 5 mg 17-β estradiol (17β-E) in the first day of treatment (day −8), 500 UI eCG (day −3) and 1.5 mg 17β-E in 24 h after sponge removal (day 0); CR ( n = 57), temporary calf removal for 120 h; CG ( n = 51), control group without treatment. Estrus rate differed among treatments ( P < 0.01) being greater in PH (78.2%), followed by CR (52.0%) and CG (22.9%). A greater proportion of cows in the PH (80.0%) and CR (54%) groups had ovulations when compared to CG (35.4%). Intervals to first estrus were 13.5 ± 6.3 days, 26.1 ± 6.4 days and 52.5 ± 7.5 days for the PH, CR and CG groups, respectively. First insemination conception was similar in the three groups. Postpartum intervals to first breeding (PFS) and to conception (PCI) were longer in CG than PH and CR groups ( P < 0.05; P < 0.01). The PH and CR groups had a similar PFS but PCI was different ( P < 0.02). Accumulated pregnancy rate at 30 and 60 but not at 90 days were different (30 days: P < 0.09; P < 0.01; P < 0.09; 60 days: P < 0.06; P < 0.01; P < 0.03) among treatments. After 90 days post-treatment, 9%, 18% and 33% of cows from the PH, CR and CG groups had not conceived. Similarly, 5.4%, 6.0% and 12.5% of cows from the PH, CR and CG groups, respectively, were culled from the herd because of lack of pregnancy after 180 days post treatment. In the group of cows evaluated by ultrasonography, only those cows having larger ovaries and dominant follicles had ovulations. It was concluded that the hormonal treatment was more efficient in inducing a fertile estrus and reducing calving to conception interval followed by the calf removal for 120 h. Each method can be considered as an important tool to reduce the postpartum anestrous period in dual purpose herds when AI is conduct in the tropics.

Productivity of different cow genetic groups in dual-purpose cattle production systems in south-eastern Mexico

The objective was to evaluate the effect of cow genetic group, nutritional level and their interaction on some economically important traits of dual-purpose herds managed under field conditions. Nine herds were monitored during a production cycle in Yucatan, Mexico. Herds were grouped into four nutritional levels (NL) based on the metabolizable energy (ME) apparently available on pasture, nutritional management, and milk production. Cows were classified into three genetic groups (GG): low (< or = 25%), middle (25-75%) and high (> or = 75%) graded for Bos taurus inheritance. Total milk sold (TMS), days in milk (DIM), TMS adjusted to DIM within each NL (TMSA), body condition score (BCS) at calving, changes of BCS during lactation (CBCS), calf weaning weight (WW), age at weaning (AW), kg of calf weaned per cow (KWC) and calf mortality were studied. The statistical model included the fixed effects of NL, GG, month of calving (MC), parity number (PN) and BCS at calving and GG x NL interaction. The effects of NL, GG, MC, PN and GG x NL were significant (p < 0.05) for TMS, KWC. As expected, TMS increased with NL from 562.4 +/- 106 kg for NL1 to 2366.3 +/- 100.1 kg for NL4. KWC was greatest for NL2 (138.6 kg) followed by NL1 (135 kg); the lowest KWC corresponded to NL4 (96.0 kg) (p < 0.05). TMS values for the middle (1727 +/- 94.7 kg) and the high graded GG (1603.5 +/- 83.5 kg) were twice those for the low graded GG cows (828.5 +/- 95 kg) (p < 0.05). KWC was also higher for the middle graded group (152.8 kg) than for the low or (104 kg) or the high graded GG (118 kg) (p < 0.05). With better nutrition cows of all GG improved their milk performance but not the calf traits. CBCS was negative for all GG. The highest BCS lost was for cows in NL1 and NL2 and for cows in the high graded GG (p < 0.05).

Effect of calf stimulation during milking on milk yield and fat content of Bos indicus× Bos taurus cows

Suckling before milking is a common practice to stimulate milk let down in Bos taurus× Bos indicus cows in dual purpose herds, extensively used in tropical American lowlands. An experiment was carried out to evaluate the influence of four cow management strategies at milking on milk yield and composition and on calves’ live weight (LW) gain. Twenty-four Brahman×Holstein cows were used to compare four treatments: without calf stimulation at milking (W), suckling before milking until let down occurred (S), calf tied beside its mother during milking (P) and suckling before milking followed by calf tied beside its mother until the end of milking (SP). The cows were machine milked twice daily, at 06:30 and 15:30 h, and suckling was allowed for 30 min after morning milking until weaning at 17 weeks. On treatments W, S, P and SP, average saleable milk yields until weaning were 7.7, 9.7, 11.4 and 9.9 kg/day ( P<0.05), consumed milk values after milking were 4.1, 2.1, 2.0 and 1.3 kg/day ( P<0.001) and calves’ LW gains were 0.61, 0.46, 0.37 and 0.41 kg/day ( P=0.056). It was shown that suckling before milking or the simple presence of calf during milking elevates the amount of saleable milk and its fat content, at the expense of consumed milk.

Economic comparison of nutritional management strategies for Venezuelan dual-purpose cattle systems

Objectives of this study were to compare three nutritional management strategies for dual-purpose herds in Venezuela in 1987 using a deterministic, multiperiod linear programming model of a representative farm. The model maximized discounted net margin (total revenues minus variable costs) from the herd for a 3-yr cow replacement cycle partitioned into six periods. The periods accounted for seasonal variation in forage availability and quality, and the model provided information about optimal animal inventories, animal sales, land in forage, and feed supplements. We compared current nutritional management practices and alternatives allowing optimal supplementation with commercial concentrate, molasses, cassava root, and urea. Iteration between the programming model and results from the Cornell Net Carbohydrate and Protein System assured technical coefficients consistent with predicted animal performance. Compared with management practices relying on commercial concentrate, optimal use of molasses and urea permitted increases in the stocking rate. Productivity and profit were restricted primarily by energy intake, which was constrained by intakes of NDF and DM. Alternative management strategies changed the relative importance of nutrient requirements and feed intake constraints. Thus, optimal interventions to alleviate nutritional constraints will vary with current management. Mobilizing adipose and protein tissues during lactation was optimal for most strategies. Supplementing with molasses and urea instead of commercial concentrate was the most profitable strategy, increasing herd net margin by 16% compared to the predominant feeding strategy in the late 1980s.

Comparative Profitability of Purebred and Crossbred Holstein Herds in Venezuela

The objective was to compare the profitability of dual purpose systems (beef and milk) with Holstein crossbred cattle in lowland ecozones with those in highland dairy systems using purebred Holsteins. Data were variable costs for feed, labor, health, and reproduction; gross incomes from milk and beef from surveys of 157 farms in 1987 to 1988; and records of dairy performance. Profit measures were milk income over feed cost for lactating cows and net margin for all cows (gross income from milk and beef minus variable costs per year). Least squares methods were used to estimate costs and profit measures from a model containing effects of breed, ecozone, herd size, reproduction system, interviewer, and milk yield as a covariate.Milk income over feed cost for daily systems was greater than for dual purpose systems, but this was a misleading profit measure because it ignores beef sales and other costs and relevant animal categories (e.g., dry cows). When these factors were considered, dual purpose systems with crossbred cows (lowest cost) and dairy systems with Holsteins had similar net margins. However, greater profits were indicated for dual purpose systems when the average milk per cow for these systems was considered to earn similar profits, eliminating the concentrate feed subsidy and the preferential exchange rate, beef production, transport costs, and fixed costs of capital. Thus, the most economical production system for Venezuela at this time is dual purpose herds with crossbred cattle in the lowland ecozones.