Impacto del tipo de encierro en sistemas mixtos sobre producción, metabolismo e indicadores de salud de la vaca lechera

El objetivo de este trabajo fue evaluar si el tipo de encierro, compost barn (CB) vs cielo abierto (CA), utilizado en sistemas mixtos, tiene impacto sobre la producción de leche, metabolismo, inmunidad, suciedad de ubre e incidencia relativa de mastitis en vacas lecheras, durante la lactancia completa, en partos de otoño y primavera. Se utilizaron vacas lecheras Holando que al parto fueron distribuidas en bloques completos al azar en dos tratamientos: CB y CA. Se registraron la temperatura y la humedad de la cama de compost y variables meteorológicas (precipitaciones, temperatura y humedad). Se registró la producción de leche individual, el peso vivo (PV) y la condición corporal (CC). Se colectó sangre para la determinación de ácidos grasos no esterificados (NEFA), β-hidroxibutirato (BHB), colesterol, proteínas totales, albúmina y globulinas y para la determinación del recuento leucocitario total (RLT) y diferencial (RLD). Se registró el score de suciedad de ubre (SSU, escala 1-4) y se estimó la incidencia de mastitis clínica. Se determinó el recuento de células somáticas (RCS) en leche y la prevalencia relativa de infección intramamaria (IIM). Las variables fueron analizadas utilizando el paquete estadístico SAS University Edition, versión 9.4, 2020. Estos análisis fueron realizados para cada época de parto (otoño y primavera), separadamente. Hubo efecto del tratamiento sobre la producción de leche, que fue de 0,7 y 0,9 L/día mayor en CB con respecto a CA, para otoño (P=0,002) y primavera (P=0,0001), respectivamente. Las variables de producción, PV, CC y todos los metabolitos variaron con los días posparto (P<0,05) en ambas épocas de parto. En la parición de primavera, se evidenció menor concentración de NEFA (P=0,02) y BHB (P=0,03) al día 15 postparto en CA con respecto a CB, y mayor concentración de BHB (cetosis subclínica) al día 90 postparto en CA con respecto a CB (P=0,004). Las vacas paridas en primavera del tratamiento CB tendieron (P=0,07) a presentar mayor concentración de proteínas totales en promedio para toda la lactancia con respecto a CA. El tratamiento CA tendió a presentar mayores RLT (P=0,09) al día 60 postparto y neutrófilos (P=0,06) al día 15 postparto, con respecto a CB. El SSU fue mayor en el tratamiento CA con respecto a CB en ambas épocas de parto (P<0,0001), estando acentuado por efecto de la lluvia en los partos de otoño (P=0,05). No se detectaron diferencias significativas entre tratamientos en la incidencia relativa de mastitis, a pesar de que SSU presentó una baja correlación con el riesgo de IIM (r=0,13; P=0,05) para las vacas del CA paridas en otoño. El uso de CB en sistemas mixtos tuvo ventajas en comparación con el CA en cuanto a producción individual y SSU. Las diferentes respuestas entre tratamientos según los días en las concentraciones de NEFA, BHB, proteínas totales y células del sistema inmune en las vacas paridas en primavera, podrían ser una alerta a los efectos ambientales en esa época de parición, a lo cual están especialmente expuestas las vacas del CA. Esta tesis demuestra el impacto del manejo ambiental sobre variables de respuesta indicadoras de metabolismo y salud

Effect of feeding management during the first 21 days postpartum, on direct and residual productive response and adaptation to grazing of multiparous Holstein dairy cows

Intensification of dairy production systems in Uruguay has involved the implementation of strategies that includes confinement with total mixed rations (TMR) either in dry lots or in low-cost barns. Questions have emerged about the productive impact of its use in short periods during early lactation (e.g., first 21 d postpartum) in multiparous dairy cows. An experiment was carried out at the Research Station “Dr. Mario A. Cassinoni” of the School of Agronomy (Paysandú, Uruguay) to study the productive response of multiparous dairy cows after a period of contrasting feeding management during the first 21 d in milk (DIM). Two treatments were compared: T21 (n = 10) were fed a TMR diet ad libitum (29.9 ± 3.5 kg DM cow−1 day−1) and T0 (n = 13) cows started grazing the day after calving and were fed a TMR (13.3 ± 0.5 kg DM cow−1 day−1 plus 1 grazing session). At d 22 the T21 cows were moved to T0 treatment until 60 DIM. Data were analyzed as a complete randomized block design using the GLIMMIX procedure of SAS OnDemand software with a mixed model that included treatment, week and the interaction as fixed effect and block as random effects. Milk production on T21 was higher than T0 (40.1 vs. 35.1 kg cow−1 day−1; P = 0.007) during the differential feeding period (0–21 DIM). During the residual period (22–60 DIM) T21 cows tended to produced more milk than T0 (39.8 vs. 38.3 kg cow−1 day−1; P = 0.07). No differences were found in grazing behavior between treatments (T0: 237, and T21: 239 min−1 grazing day−1, P = 0.86). It seems that these differences in milk production might be related to a carryover effect of higher dry matter intake during the transition period as well as changes in selectivity (Chilibroste et al., 2015; Menegazzi et al., 2021). Changes in feeding management during the first 21 DIM had an impact on milk production of multiparous dairy cows. Further research is required to better understand the mechanisms involved in the direct and residual responses

Contrasting feeding management in the first 21 days postpartum in Holstein dairy cows: direct and residual milk responses

The transition period and its management affect how dairy cows face physiological challenges. Total mixed rations (TMR) have been shown as a strategy to address pasture-based system limitations and improve milk production, without consistent information about their use in short periods and residual responses. The study aimed to evaluate contrasting feeding management in the first 21 days postpartum on direct and residual milk production responses until 60 days in milk (DIM). Sixty-seven mixed parity Holstein dairy cows were used in a completely randomised block design in two treatments across two trials: MD-MD, cows fed a mixed diet (MD) with grazing and supplementation with mixed ration, from calving until 60 DIM, TMR-MD: confined cows with TMR provided ad libitum during the first 21 DIM in a compost-bedded pack barn and changed to MD at 22 until 60 DIM. During the first 21 DIM (direct response), cows fed TMR produced 11.7% more milk than those on MD-MD. Multiparous (M) TMR-MD obtained 18.6% higher milk yield than M MD-MD cows, but no significant differences were detected between primiparous (P) cows. After the switch at 22 DIM (residual response), no significant differences were detected between treatments in milk yield. However, the interaction between treatment and parity indicates that M TMR-MD cows exhibited 3.6% more milk than those in MD-MD, as a carryover effect. In contrast, P cows did not differ between treatments. In the first 21 DIM, TMR-MD cows achieved a higher fat concentration and protein yield than MD-MD. Fat yield tended to increase in TMR-MD compared to MD-MD, without treatment effect for lactose yield. In the residual period, TMR-MD cows had higher pro-tein concentrations and tended towards higher fat concentrations than MD-MD cows. The interaction between treatments and parity showed that P TMR-MD cows had higher protein and exhibited a trend towards higher fat concentration than P MD-MD cows. The differential feeding management during the first 21 DIM did not generate differences in body condition score (BCS), between treatments or par-ities. In the residual period, TMR-MD cows achieved a higher BCS than MD-MD cows without differences between parities. No differences were found between treatments in grazing and ruminating time, reflect-ing a successful adaptation of TMR-MD cows. In conclusion, feeding TMR during the first 21 DIM is an effective strategy for increasing milk yield and achieving short-term carryover effects in M, but not in P cows

Feeding strategies during fresh cow period in pasture-based dairy systems: metabolic adaptation to lactation and resumption of ovarian cyclicity in primiparous and multiparous cows

Pre-printThe study aimed to determine whether confinement with total mixed ration (TMR) during the first 21 days in milk (DIM), followed by grazing supplemented with partial mixed ration (PMR), alleviates negative energy balance, enhancing productive performance and accelerating the resumption of ovarian cyclicity in primiparous and multiparous dairy cows, relative to a control group managed on grazing supplemented with PMR after calving. Following calving, 16 primiparous and 24 multiparous Holstein dairy cows were blocked and randomly distributed in two treatments: one included grazing plus supplementation with PMR after calving (T0), while the other one involved confinement with TMR ad libitum during the first 21 DIM and the same feeding management of T0 from day 22 onwards until 60 DIM (T21). Primiparous cows showed no significant differences between treatments in milk production. However, T21 primiparous cows displayed lower non-esterified fatty acids (NEFA), greater glucose, and greater insulin and IGF-1 concentrations compared to T0 primiparous cows during the 21 DIM of the feeding management. In contrast, multiparous T21 cows achieved greater milk production during the first 21 DIM, with no differences in NEFA and BHB levels but greater insulin and IGF-I concentrations than multiparous T0 cows. Both parity groups in T21 underwent an extra metabolic adaptation following the management change at 22 DIM, increasing NEFA and BHB concentrations, and decreasing milk production during this period. Despite the improved endocrine-metabolic profile observed in T21 during the first days postpartum, no differences were found in the resumption of ovarian cyclicity which was shorter in multiparous than primiparous cows. Untargeted metabolomics supported evidence that primiparous cows grazing from calving had greater lipid and muscle mobilization than other groups, reflected by lower glucose and greater creatinine, dimethylglycine, and formate. Strategic feeding management during the fresh cow period affects the metabolic adaptation to lactation, but milk production responses were observed only in multiparous cows, reflecting parity-specific homeorhetic priorities

Increased expression of interferon-stimulated gene 15 (ISG15) in cervical cells on day 14 of pregnancy in Holstein heifers

In cattle, expression of IFN-stimulated genes in the female reproductive tract has been reported as an early pregnancy diagnostic tool, as early as d 17 of pregnancy. The hypothesis of this study was that expression of ISG15 in the cervix of pregnant heifers is increased on d 14 of pregnancy. The objective was to compare the expression of ISG15 in cervical cells between pregnant and cyclic heifers (control, sham-inseminated) on d 14, 16, and 18 after insemination (d 0). Holstein heifers were submitted to an estrus synchronization protocol and inseminated with extender only (“control,” n = 6), or with regular semen (n = 15). Heifers were classified as pregnant (n = 10) by ultrasound at d 30 through the detection of a viable embryo with a heartbeat. Blood samples from the coccygeal vein were collected to determine serum progesterone concentrations on d 14, 16, and 18. The expression of ISG15 and PGR in cervical cells collected through cytobrush was measured on d 14, 16, and 18. A receiver operating characteristic (ROC) curve was calculated to quantify the pregnancy diagnostic accuracy of ISG15 and PGR expression. The expression levels of ISG15 in cervical cells were significantly greater in pregnant compared with control heifers on d 14, and remained greater on d 16 and 18, whereas differences in PGR were observed only on d 18. Scatter plots and ROC analyses showed the most accurate prediction of pregnancy for ISG15 on d 16. In conclusion, cervical cells express greater ISG15 mRNA in pregnant versus control heifers as early as d 14 postinsemination, with the best accuracy on d 16