Dual-purpose Cows Research Articles

Blood metabolite concentration, milk yield, resumption of ovarian activity and conception in grazing dual purpose cows supplemented with concentrate during the post-partum period.

Cattle grazing on natural pasture face seasonal variation in pasture availability and nutritive value. Improving the nutrition of cows by providing supplementary feeds during periods of pasture or nutrient deficit is necessary for improved productivity. This study was conducted to determine the effect of feed supplementation during the post‐partum period on the metabolic status and reproductive performance of 40 grazing Sanga and Friesian × Sanga cows. Twenty out of a total of 40 cows (10 Sanga and 10 Friesian × Sanga cows) were supplemented with 2.5 kg of concentrate per day for 16 weeks after calving. Parameters measured include daily milk yield, concentration of blood metabolites, resumption of ovarian activity and conception. Supplemented cows had higher partial milk yield than their non‐supplemented counterparts (2.07 vs. 1.60 kg/day; P < 0.001). Sanga cows had lower milk yield than the Friesian × Sanga crossbreds (1.61 vs. 2.05 kg/day; P < 0.01). Supplemented cows had higher mean total protein (86.7 vs. 81.3 g/L; P = 0.007) and globulin (53.0 vs. 47.7; P = 0.014) concentrations than non‐supplemented cows. Sanga cows had higher glucose (P = 0.027), total protein (P < 0.001) and globulin (P < 0.001) but lower triglyceride (P = 0.003) and progesterone (P = 0.023) concentrations than Friesian × Sanga cows. Supplemented cows had less proportion not cycling (20 vs. 55%; P = 0.022) and less days open (95.8 vs. 106 days; P = 0.032) than non‐supplemented cows. The Friesian × Sanga cows had higher progesterone concentrations at first progesterone rise (3.34 vs. 1.32 ng/mL; P = 0.032) and shorter interval from calving to conception (96.7 vs. 106 days; P = 0.042). The results from this study indicate the beneficial effects of feed supplementation in terms of increased milk yield, better metabolic status and reproductive performance.

Segmented regression to describe cumulative milk production of grazing dual-purpose Holstein-Zebu cows.

The objective of this study was to compare the fit of seven functions to cumulative daily milk yield records of grazing F1 (Holstein × Zebu) cows in a dual-purpose cattle production unit of the Mexican tropics. Fifty-seven lactations from cows that calved from 1998 to 2001 were used. The functions were quadratic without intercept, three with two segments (both segments linear, the first segment quadratic and the second linear, and both segments quadratic), and three classical growth functions (Gompertz, logistic, and Richards). The Akaike information criterion corrected (AICC) was used as criterion of fit, being the function with the best fit the one with the lowest AICC value. The best fit was for the segmented function with both segments quadratic, followed closely by the Richards function. The derivatives of these functions give the daily milk yield curve (kg/cow/day), so the former results in a straight line per segment and the latter in the usual shape of the typical lactation. However, as cumulative records produce a monotonic increasing line, neither function can distinguish a priori the presence of a lactation peak. For this reason, it is advisable to examine the common dispersion plot of daily milk yield of each cow, and if a peak is not evident, then proceed to fit the segmented function; otherwise, the function of Richards should be used. The need to study the causes for the absence of a lactation peak in tropical dual-purpose cows is highlighted.

Associations between precision sensor data with productivity, health and welfare indicator traits in native black and white dual-purpose cattle under grazing conditions

The aim of the study was to analyse the relationships between conventional production as well as subjectively scored welfare assessment traits with longitudinal sensor measurements (i.e., behavioural activity traits) of dual-purpose cattle kept in grazing systems. Such aim implies getting knowledge into dual-purpose cow grazing behaviour, and inferring behaviour trait thresholds from a management perspective (e.g., development of an early-warning system for clinical mastitis). In this regard, 49 native black and white dual-purpose cows from the breed Deutsches Schwarzbuntes Niederungsrind (DSN) were equipped with electronic sensor ear tags (accelerometer attached to radio frequency identification tag). Over a period of twelve months including two grazing seasons, ear sensors recorded individual cow behaviour for rumination, feeding, lying, active, and highly active, as well as ear surface temperature. Data for all traits were transformed into the measurement unit “percent per day”. Additionally, a trained classifier subjectively scored welfare assessment traits (body condition score, locomotion score, udder/ leg hygiene score) and temperament traits (intra-herd rank order, aggressiveness and general temperament during milking). A third trait category included official test-day records for milk-kg, fat-kg and somatic cell count. Association analyses focussed on trait correlations, and on mixed model applications (i.e. defining fixed effect classes for explanatory sensor traits). Sensor ear temperature was significantly negatively correlated with feeding behaviour (r=−0.17, P < 0.01), but significantly positively correlated with walking activity (r = 0.20, P < 0.001). Regarding subjectively cow welfare and temperament scoring, we found positive correlations between the level of aggressiveness towards other herd mates and the intra herd rank order (r = 0.36, P < 0.001), indicating that cows with a higher intra-herd rank showed increased aggressive behaviour. Mixed model analysis revealed that DSN cows spending more time lying down (>7 h/d) had reduced daily milk and fat yields. Oppositely, high yielding cows showed intensive feeding and rumination behaviour. A substantial decrease in rumination and feeding time was observed for cows with elevated somatic cells (>700,000 cells/mL), suggesting utilisation of sensor behaviour as an indicator for udder health. We identified significantly higher body condition scores for cows with increased lying times, whereas active cows with high daily feeding and rumination times had quite low body conditions scores. Hence, optimal health and behaviour monitoring for cows in grazing systems implies consideration of both trait components objectively recorded longitudinal sensor traits and subjectively scored behaviour and health indicators. Overall, individual behaviour pattern variation was detected, via sensor technology for dual-purpose cows kept in grazing systems. Hence, automatically recorded longitudinal sensor data is a proper alternative for cow phenotyping in extensive grassland systems, aiming on an accurate data basis for genetic evaluations.

Multi-breed herd approach to detect breed differences in composition and fatty acid profile of cow milk

The objective of the present study was to estimate the effect of breed on milk fatty acid (FA) composition of dairy (Brown Swiss, Holstein-Friesian, and Jersey) and dual-purpose cows (Simmental and Alpine Grey) in multi-breed herds. Information on individual milk samples was collected during routine cow milk testing between 2011 and 2014, and consisted of 285 606 observations from 17 445 cows in 617 herds. Fixed effects included in the mixed model were breed, parity, stage of lactation and the interaction between parity and stage of lactation, and random effects were cow, herd-test-date and residual. Contrast estimates for the studied traits were used to compare specific sets of breeds. Holstein-Friesian produced more milk than the other cattle breeds, with the greatest trans FA and C18:1 and the lowest C18:0 content. Comparison between the specialised dairy vs the dual-purpose breeds highlighted significant differences for all traits except for polyunsaturated FA and trans FA content. Specialised dairy breeds had greater milk saturated FA, short-chain FA, medium-chain FA, C14:0 and C16:0 content, and dual-purpose breeds produced milk with greater content of monounsaturated FA, long-chain FA, C18:0 and C18:1. Results demonstrated that, although specialised dairy produced more milk than dual-purpose breeds, milk FA profile of the latter was more favourable from a human nutrition point of view.

Are cheese-making properties of dual purpose cattle impaired by highland grazing? A case study using Aosta Red Pied cows

Summer transhumance is often practiced in mountainous farming systems. It includes moving dairy cows from lowland (LO) to highland (HI) pastures during summer. It is known that high genetic merit cows are susceptible to the HI conditions, but it is unclear if this also applies to more adapted, regional cow types. The present study aimed to investigate the effect of HI sojourn on cheese-making properties of Aosta Red Pied cows, a dual purpose cattle type. Milk coagulation properties were measured in the milk of 47 cows before and after transhumance. Sources of variation were investigated using linear mixed models, including parity, site, milking time, the interaction parity × site, milking time × site and milking time × parity. Cow was nested within site, and used as subject for repetition, and sampling date was included as repeated factor. Curd-firming time and curd firmness did not vary between LO and HI, whereas rennet coagulation time was prolonged in HI compared to LO in both primiparous (16.4 vs. 18.5 min) and multiparous cows (17.5 vs. 21.1 min, respectively). The percentage of non-coagulating samples was greater in HI (15.0%) compared to LO (8.5%). The lower milk reactivity to rennet addition in HI seems to be mostly related to the simultaneously increasing somatic cell score. Morning and evening milk were similar in coagulation properties. In conclusion, even indigenous dual purpose cows were affected by HI conditions and the experience the multiparous cows had with the transhumance was not helpful either.

Efectos No Genéticos sobre la Reproducción en Vacas Mestizas con Predominio Bos indicus en el Municipio de Arauca, Colombia

&lt;p&gt;Los factores no genéticos o ambientales son la principal causa de variación de los parámetros reproductivos en vacas mestizas en regiones tropicales. El objetivo fue determinar algunos factores no genéticos que afectan la edad al primer parto (EPP) y el intervalo entre partos (IEP) en vacas doble propósito en el municipio de Arauca, Colombia. Se analizó la información de 176 y 110 datos de EPP e IEP de vacas con predominio de razas &lt;em&gt;indicus&lt;/em&gt;. Se consideró el efecto de los factores fijos para EPP: Finca (FIN: 1, 2, 3), época de primer parto (EPPP: seca, lluviosa), año de primer parto (APP: 1992….2011), sexo de la cría (SCR: M, H). Para IEP: finca (FIN), época de intervalo entre partos (EIP), año de intervalo entre partos (AIEP), sexo de la cría (SCR) y numero de parto (NP: 1…5). Los datos se analizaron utilizando los procedimientos GLM de SAS y para la comparación de medias se usó el test Duncan con un nivel de significancia 5%. La media estimada para la EPP fue de 1243,56±160,3 días y para el IEP fue de 608,03 ±165,4 días. La FIN y el APP fue un factor de variación significativo (p&amp;lt;0,05) para la EPP, mientras que El NP y el AIEP fue un factor de variación significativo (p&amp;lt;0,05) para el IEP. Los demás factores no fueron significativos (p&amp;gt;0,05) para los parámetros analizados. Se concluye que la influencia ambiental sobre los parámetros reproductivos depende de la región donde se localice el sistema de producción y se relaciona con el manejo técnico y productivo propio de cada finca. Los valores encontrados se consideran adecuados para el sistema de producción dada las condiciones de manejo en la sabana inundable y está dentro del rango establecido para los grupos raciales con predominio de las razas cebuinas.&lt;/p&gt;

Effects of temperament on production and reproductive performances in Simmental dual-purpose cows

Abstract The aim of the current research was to evaluate the effects that temperament has on production and reproduction performances in Simmental dual-purpose cattle breed. Behavioral reactivity of cows significantly influenced ( P ≤ 0.05) the body weight, milk yield, fat yield, protein yield, protein content, and the calving interval of the cows included in the study-head, having more substantial effects ( P ≤ 0.001) on the milking speed and the number of steps per day, with calmer cows outperforming the nervous counterparts. However, temperament did not influence ( P > 0.05) traits such as days open, number of inseminations per gestation, fat percentage, somatic cell count, body condition score, cleanliness of udder and cleanliness of hindquarter. Significant negative phenotypic correlations were found between temperament and cows body weight (−0.19), milk yield (−0.19), fat yield (−0.14), protein yield (−0.18), and milking speed (−0.18). Current results suggest that selection for calm temperaments will translate into increased milk, fat, and protein yields in Simmental cattle, as well as shorter the calving interval and improved milk ejection.

Dairy cattle assessment using specialization indices and productive performance typicality

It would seem essential to create animals of the required types in view of the availability of various strains differing in the levels of productive performance within the breeds for dairy and dual-purpose production. Monitoring the herds of Black-and-White and Simmental cattle for the type of production (high production dairy type, dairy type, and duel-purpose: dairy-beef and beef-dairy types) was carried out using various methods. The extra milk yields from the high producing dairy cows of the Simmental breed and the Holstein F1 crossbreds as compared to the peers of the other types ranged from 469 kg to 1391 kg and from 555 kg to 1734 kg, respectively. Irrespective of any breed and selection, the cows of a dairy type as compared to the peers of a dual-purpose type tended to produce higher yields by 563 kg (P > 0.95), 1140 kg (P > 0.99), and 1173 kg (P > 0.99) from the cows of the Black-and-White breed, the Holstein breed of the domestic selection, and the Holstein breed of the American selection, respectively. The milk of dual-purpose cows as compared to the milk of dairy cows was characterized by higher butterfat content (by 0.06–0.08% on average). The methods applied to identify the parameters for conformation and production traits simultaneously are the most informative techniques to evaluate the production type of cows.

Molasses supplementation for dual-purpose cows during the dry season in subtropical Mexico.

The effect of including 9% of molasses in supplements offered to dual purpose cows, during dry season in subtropical Mexico was determined. Forage availability in pastures during the dry season is reduced and of low quality. Molasses is a readily available source of energy that may improve forage utilization and could have a positive effect on cow's milk production and calves daily weight gain (CDWG). Twelve multiparous Brown Swiss cows (409 ± 33kg of body weight and 136 ± 73days in milk), and their calves were randomly assigned to two supplements (six cows per treatment). Control supplement (COS) consisted of cracked maize ears (CME), soybean meal and urea (14% CP), and experimental supplement in which 9% of CME was replaced by molasses (MOS). Cows received 4.5kg/cow/day dry matter (DM) of supplement. Experiment lasted 10weeks divided in five experimental periods (EP). Animal responses (milk yield, milk composition, body weight, body condition score and CDWG) were recorded at the end of every EP. A linear mixed model was used to analyse the data as a complete random design. Net profits from milk and beef due to supplements were estimated using partial budget approach. Average milk yield was 7 (kg/cow/day) with 30.6, 30.4 and 42.5 (g/kg milk) of fat, protein and lactose, respectively. Average cow weight was 422kg and CDWG was 0.8kg/day. No significant responses on animal production variables were found when 9% of MOS was included in the supplement; however, total net income increased on 4%, due to higher CDWG.

Toward improved postpartum cyclicity of primiparous dairy cows: Effects of genetic merit for production traits under contrasting feeding systems

Milk genetic merit is known to affect commencement of luteal activity (C-LA) in dairy cows. This effect is considered to be due to energy exported in milk production. The present study aimed to identify and quantify the effects of genetic characteristics [breed and estimated breeding value (EBV) for milk yield and fat and protein contents] and feeding system on C-LA of primiparous cows. From 2006 to 2013, an experiment was conducted on 97 primiparous dairy (Holstein) and 97 primiparous dual-purpose (Normande) cows. Within breed, cows were classified into 2 groups: cows with high EBV for milk yield were included in a “milk group” and those with high EBV for fat and protein contents were included in a “content group.” Within breed, exported energy in milk and body weight (BW) loss were similar for both genetic groups. Two grazing-based strategies were used, a high feeding system (maize silage in winter and grazing plus concentrate) and a low feeding system (grass silage in winter and grazing with no concentrate). Interval from calving to C-LA was studied performing survival analyses. Milk progesterone profile, milk yield, and body condition were analyzed using χ2-test and analysis of covariance. Holstein cows produced more milk (+1,810kg in the high feeding system and +1,120kg in the low feeding system) and lost more BW from wk 1 to 14 of lactation (−1.4kg/wk) than Normande cows, whereas Normande cows had earlier C-LA than Holstein cows. Within breed, cows in the content group had earlier C-LA (associated hazard ratio=2.0) than cows in the milk group. Body weight at calving and loss from wk 1 to 14 of lactation tended to be associated with later C-LA. Cows in the high feeding system produced more milk (+2,040kg for the Holstein cows and +1,350kg for Normande cows) and lost less BW from wk 1 to 14 of lactation (+3.8kg/wk) than cows in the low feeding system. No effect of feeding system or milk yield was observed on C-LA. Prolonged luteal phases were frequent (18% of cows) and were not associated with either breed or genetic group. Ovarian cycles were longer for Holstein than for Normande cows (+1.7d) because of a longer luteal phase and a longer interluteal interval. Results of the study could be useful to establish strategies to manage declining reproductive performances at genetic and environmental levels. This study showed that cows with a genetic predisposition to export milk energy through fat and protein contents had earlier C-LA than predisposed to export milk energy through yield.

Milk production and reproduction of dual-purpose cows with a restricted concentrate allowance and access to an association of Leucaena leucocephala and Cynodon nlemfuensis

The aim of the study was to evaluate the productive and reproductive performance of dual-purpose (DP) cows with a restricted concentrate allowance and access to a forage association of Leucaena (Leucaena leucocephala) and Stargrass (Cynodon nlemfuensis). Twenty-four multiparous Holstein × Zebu cows were used during the first 98 days postpartum. Treatments were control (CT): nightly grazing of Stargrass + commercial concentrate (3.97 kg dry matter [DM]/d), and Leucaena (LT): nightly grazing of Stargrass + commercial concentrate (1.97 kg DM/d) + 4 h grazing on an association of Leucaena/Stargrass. The actual time spent browsing Leucaena represented 38% of the total time of consumption. The bite rate of Leucaena was 22 5 bites/min with a bite size of 0.541 ± 0.08 g DM. The estimated intake of Leucaena per cow was 503 ± 228 g DM/d. Milk yield per cow was similar (P > 0.05) between treatments (CT = 12.28 ± 0.6 kg/d, LT = 11.97 ± 0.6, TL = 11.9 0.6) with a similar composition (P > 0.05). There were no differences (P > 0.05) between treatments for changes in live weight (CT −29.6 kg, LT −33.3 kg) and body condition (CT −1.3, LT −1.4, in a 1–9 scale). Population of ovarian follicles per cow was similar between treatments throughout the experiment. Pregnancy rate was 33% for CT and 25% for LT, with no significant differences (P > 0.05). Grazing an association of Leucaena and Stargrass can replace part of the concentrate without detrimental effects on production and reproduction in DP cows.

Factors associated with age at slaughter and carcass weight, price, and value of dairy cull cows

The sale of cull cows contributes to the overall profit of dairy herds. The objective of this study was to quantify the factors associated with slaughter age (mo), cow carcass weight (kg), price (€/kg of carcass weight), and value (€/head) of dairy cull cows. Data included 20,995 slaughter records in the period from 2003 to 2011 of 5 different breeds: 2 dairy [Holstein Friesian (HF) and Brown Swiss (BS)] and 3 dual-purpose [Simmental (Si), Alpine Grey (AG), and Rendena (Re)]. Associations of breed, age of cow (except when the dependent variable was slaughter age), and year and month of slaughter with slaughter age, carcass weight, price, and value were quantified using a mixed linear model; herd was included as a random effect. The seasonal trends in cow price and value traits were inversely related to the number of cows slaughtered, whereas annual variation in external factors affected market conditions. Relative to BS cows, HF cows were younger at slaughter (73.1 vs. 80.7mo), yielded slightly lighter carcasses (242 vs. 246kg), and received a slightly lower price (1.69 vs. 1.73€/kg) and total value (394 vs. 417€/head). Dual-purpose breeds were older and heavier and received a much greater price and total value at slaughter (521, 516, and 549€/head, respectively for Si, Re, and AG) than either dairy breed. Of the dual-purpose cows, Si carcasses were heavier (271kg), whereas the carcasses of local breeds received a higher price (2.05 and 2.18€/kg for Re and AG, respectively) and Alpine Grey cows were the oldest at slaughter (93.3mo). The price per kilogram of cull cow carcasses was greatest for very young cows (i.e., <3yr of age) and the differential in price and value between younger and older cows was greater in dual-purpose than in dairy breeds. Large differences in cull cow whole carcass value (carcass weight × unit price) among dairy breeds suggest that such a trait could be considered in the breeding objectives of the breeds.

Low crude protein diets and phase feeding for double-muscled crossbred young bulls and heifers

This study aimed to evaluate the effect of underfeeding dietary crude protein (CP) during the whole or part of the fattening period on growth performance, dry matter intake (DMI), carcass and meat quality traits of crossbred bulls and heifer calves obtained from double-muscled (DBM) Belgian Blue (BB) sires and dairy or dual purpose cows. Twenty-four crossbred BB sired young bulls and 30 BB sired heifer calves (236±27.0kg BW) were housed in 12 pens with males separated from heifers. They received a control diet (CP14) with 140g CP/kg DM for the whole experiment (CPHH) or a low-protein diet (CP10) with 102g/kg CP/kg DM for the whole experiments (CPLL) or CP14 for the first 90 days and CP10 for the remaining days (94 days on average) of finishing period till slaughtering (CPHL), which occurred when heifers and bulls reached 485 and 535kg BW, respectively. Compared to CPHH and CPLL calves, CPHL animals evidenced faster ADG (P<0.05), albeit the magnitude of this effect was limited (on average+6.3%). During the whole trial no differences among groups were observed for DM intake (8.9kg/d), gain:feed ratio (0.144), carcass weight (301kg), carcass yield (589g/kg BW), SEUROP carcass muscularity (U+) and for most of the meat quality traits. Only meat shear force was increased (P=0.04) by CPLL treatment compared to CPHH and CPHL (+17%). Bulls and heifers differed for growth performance and for many carcass and meat traits, but gender did not interact with dietary treatment for any trait. It was concluded that little benefits would be achieved using CP14 for the entire or part of the fattening period on these crossbreds. Beside, this paper covers a lack of information about quality traits of crossbred heifers and young bulls obtained from DBM BB sires and dairy and dual purpose dams showing that carcass and meat quality traits of these subjects are comparable or better than those achievable from non-DBM beef breeds cattle.

Genetic parameters for linear type traits in the Rendena dual-purpose breed.

The aim of the study was to estimate the genetic parameters for five composite traits and 20 individual type traits on 10,735 first-parity Rendena dual-purpose cows. Fixed effects included in the linear animal mixed models were herd-year-classifier, days in milk and age at first calving; the additive genetic effect of the animal was included as a random effect. Heritability estimates varied from 0.12 (feet) to 0.52 (stature). Genetic correlations between the individual body size traits were all ≥0.69; similar strong genetic correlations existed between traits describing similar morphological characteristics (e.g. mammary system, fleshiness). Many of the body size traits were negatively genetically correlated with animal fleshiness. Genetic trends showed that genetic merit for body size increased consistently over the last 10 years, while genetic merit for fleshiness declined. These results suggest that the characteristics of the dual-purpose Rendena cattle are becoming more like specialized milk-producing animals. Nonetheless, sufficient genetic variation exists to halt or reverse the deterioration in fleshiness.

Factores que afectan la vida útil de vacas doble propósito

RESUMENObjetivo. Determinar el efecto de factores no genéticos y de grupo racial, sobre la vida útil (VU) de vacas doble propósito. Materiales y métodos. Se utilizó información de 2098 vacas, que incluyó a todas las hembras que ingresaron a servicio y salieron del sistema productivo. La VU se cuantificó como el total de partos al salir del rebaño. Los efectos incluidos en el modelo fueron hacienda (H: AG, VV), año de primer parto (A1P: 1995-2006), época de primer parto (E1P: Enero-marzo, abril-mayo, junio-agosto, septiembre-diciembre) grupo racial (GR: C, 50C50E, ML) y las interacciones HxGR y A1PxGR. Resultados. La media de VU fue de 2.63 partos ± 0.07. Todos los factores tuvieron efectos altamente significativos (p&lt;0.01) sobre VU, menos H. Es interesante resaltar que las interacciones HxGR y A1PxGR fueron altamente significativas (p&lt;0.01) indicando que los grupos raciales se comportan diferente en cada hacienda y en el transcurso de los años. Conclusiones. Los efectos no genéticos y de grupo racial tienen una alta influencia sobre VU.

FACTORES QUE AFECTAN LA PRODUCCIÓN DE LECHE EN VACAS DE DOBLE PROPÓSITO EN TRÓPICO HÚMEDO (PUCALLPA)

The effect of feeding, crossbreeding level, lactation period, and reproductive status on milk yield was evaluated in dual purpose cows in the humid tropics of Peru. A total of 204 cows from 23 farms were monitored. All cows grazed over Brachiaria decumbens. Energy supplementation consisted of brewery residues and rice bran. Cows were grouped according to the level of European blood in Low, Medium, and High. Regression analysis and the “t” Student test were applied for statistical comparisons. The higher availability of B. decumbens had a negative effect on milk yield. Supplemented animals yielded more milk (5.2 kg/cow/day) than those non-supplemented (3.8 kg/cow/day). The level of European inheritance affected milk yield, where 50% crossbred cows had the highest milk yield (5.0 kg/cow/day). Month of lactation affected productive performance. Non-pregnant cows produced more milk than the pregnant ones (4.5 vs. 3.7 kg/cow/day). It is concluded that milk yield was affected by all variables under evaluation, especially the level of European blood.

Rendimiento de forraje de gramíneas de corte y efecto sobre calidad composicional y producción de leche en el Caribe seco

La estacionalidad climática afecta la oferta de nutrientes en los sistemas ganaderos. En la búsqueda de diferentes estrategias para la alimentación del ganado, se evaluó el efecto de la fertilización nitrogenada de cuatro gramíneas de corte sobre el rendimiento, la calidad del forraje en vacas doble propósito en el Valle del Cesar. Se desarrollaron dos fases, la primera, consistió en la evaluación del rendimiento y calidad del forraje, dónde los datos se analizaron por un diseño en bloques al azar, con un arreglo factorial de cuatro forrajes y cinco fuentes nitrogenadas; la segunda fase consistió en la evaluación de la respuesta animal; se suministró forraje conservado basados en los resultados de la primera fase; se aplicó un diseño experimental de sobrecambio. Se utilizaron 8 vacas doble propósito en el segundo tercio de lactancia con un peso (PV) de 395 kg aproximadamente. El estudio se realizó en la Estación Experimental Motilonia, Corpoica. El tipo de pastura afecto significativamente el valor de la materia seca, siendo mayor en el pasto Elefante (17,9%) y menor en el King-grass morado (13,3%); el rendimiento de forraje fue afectado tanto por la fertilización, como por la pastura, siendo mayor en la aplicación de urea y en asociación con Leucaena sp. (12,9 y 12,7 t ha-1, respectivamente). La fertilización no tuvo efecto sobre la composición química de las gramíneas. Se obtuvo una mayor producción de leche, cuando se suministró ensilaje de pasto Elefante + Leucaena sp. y de Elefante solo (3,98 ± 0,18 y 3,81 ± 0,18 L/vaca/día), en comparación con la alimentación sin suministro de ensilaje. La calidad composicional de la leche se vio afectada positivamente por el suministro de ensilaje.

Pasture shade and farm management effects on cow productivity in the tropics

Shade, provided by trees within pastures, can affect cattle productivity through mitigating heat stress and by altering understorey pasture growth and cattle behaviour. Using mixed effects models, we studied the effect of pasture tree shade and farm management on milk yield and individual body score on dual purpose cows in six silvopastoral farms in the Rivas province of Nicaragua. Milk production reduced with time in milk (lactation stage) while access to shade did not have any significant effect on milk yield. Body condition was negatively affected by pasture shade. In addition, feed supplementation and corralling at night positively affected body condition scores. Cattle in our study paddocks had relatively good access to shade and consequently shade may not be a limiting production factor. Since tree shade did affect body condition negatively it may be that a reduced tree cover could increase the availability of grass pasture with a positive effect on cattle production parameters.

Limitations and potentials of dual-purpose cow herds in Central Coastal Veracruz, Mexico

Feed chemical and kinetic composition and animal performance information was used to evaluate productivity limitations and potentials of dual-purpose member herds of the Genesis farmer organization of central coastal Veracruz, Mexico. The Cornell Net Carbohydrate and Protein System model (Version 6.0) was systematically applied to specific groups of cows in structured simulations to establish probable input–output relationships for typical management, and to estimate probable outcomes from alternative management based on forage-based dietary improvements. Key herd vulnerabilities were pinpointed: chronic energy deficits among dry cows of all ages in late gestation and impeded growth for immature cows. Regardless of the forage season of calving, most cows, if not all, incur energy deficits in the final trimester of gestation; thus reducing the pool of tissue energy and constraining milking performance. Under typical management, cows are smaller and underweight for their age, which limits feed intake capacity, milk production and the probability of early postpartum return to ovarian cyclicity. The substitution of good-quality harvested forage for grazing increased predicted yields by about one-third over typical scenarios for underweight cows. When diets from first parturition properly supported growth and tissue repletion, milk production in second and third lactations was predicted to improve about 60%. Judiciously supplemented diets based on good quality grass and legume forages from first calving were predicted to further increase productivity by about 80% across a three-lactation cow lifetime. These dual-purpose herd owners have large incentives to increase sales income by implementing nutritional strategies like those considered in this study.

Economic analysis of alternative nutritional management of dual-purpose cow herds in central coastal Veracruz, Mexico.

Market information was combined with predicted input–output relationships in an economic analysis of alternative nutritional management for dual-purpose member herds of the Genesis farmer organization of central coastal Veracruz, Mexico. Cow productivity outcomes for typical management and alternative feeding scenarios were obtained from structured sets of simulations in a companion study of productivity limitations and potentials using the Cornell Net Carbohydrate and Protein System model (Version 6.0). Partial budgeting methods and sensitivity analysis were used to identify economically viable alternatives based on expected change in milk income over feed cost (change in revenues from milk sales less change in feed costs). Herd owners in coastal Veracruz have large economic incentives, from $584 to $1,131 in predicted net margin, to increase milk sales by up to 74% across a three-lactation cow lifetime by improving diets based on good quality grass and legume forages. This increment is equal to, or exceeds, in value the total yield from at least one additional lactation per cow lifetime. Furthermore, marginal rates of return (change in milk income over feed costs divided by change in variable costs when alternative practices are used) of 3.3 ± 0.8 indicate clear economic incentives to remove fundamental productivity vulnerabilities due to chronic energy deficits and impeded growth of immature cows under typical management. Sensitivity analyses indicate that the economic outcomes are robust for a variety of market conditions.