Search

Level of dam milk production (DMP) and dam milk fat to protein ratio (DFPR), as an indicator of metabolic status in dairy cows, have been identified to be associated with productive and reproductive performance of the offspring. Yet whether the interaction of DMP by DFPR can be associated with performance of the offspring have not been studied to our knowledge. Therefore, the present study was conducted to investigate the association of the main and interactive effects of DMP and DFPR with offspring's birth weight, survival, milk yield and fertility. To this end, data of birth weight, culling rate, milk yield and reproductive variables of offspring born to lactating dams (n = 14,582) and data associated with DMP and DFPR during 305-day lactation were retrieved. Afterwards, offspring were classified in three categories of DMP, including DMP1 (dams with <10.00 × 10 3  kg of 305-day milk production), DMP2 (dams with ≥10.00 × 10 3  kg and <14.00 × 10 3  kg of 305-day milk production), DMP3 (dams with ≥14.00 × 10 3  kg of 305-day milk production), and three categories of DFPR, including DFPR1 (offspring born to dams with <1.00 FPR), DFPR2 (offspring born to dams with ≥1.00 and < 1.40 FPR) and DFPR3 (offspring born to dams with ≥1.40 FPR). Statistical analysis revealed no association of the interaction effect of DMP by DFPR with investigated variables in the offspring (P > 0.05). However, the main effect of DMP was positively associated with milk yield, but negatively associated with survival, age at first insemination and conception during nulliparity, and transgenerational improvement in milk yield in the offspring (P < 0.05). Moreover, the main effect of DFPR was positively associated with birth weight, survival and first service conception rate during nulliparity, but negatively associated with metabolic status and reproductive performance during primiparity in the offspring (P < 0.05). In conclusion, the present study did not find any interaction effect of DMP by DFPR on productive and reproductive variables in the offspring. This finding implicates the association of DMP with milk production in the offspring was regardless of DFPR. Moreover, this finding implies the association of DFPR with postpartum metabolic status and reproductive performance in the offspring was regardless of DMP., Competing Interests: Declaration of competing interest The authors have no conflict of interest to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Although some studies investigated the relationship of dam milk production (DMP) with offspring birth weight and productive performance, limited information is available on the association of level of DMP with reproductive performance in dairy cows. Therefore, the present study was conducted to understand whether dams with various levels of milk production produce offspring with different fertility. In study I, offspring were classified based on the level of DMP into five categories, including DMP1 (dams with <10.00 × 10 3  kg of 305-day milk production), DMP2 (dams with ≥10.00 × 10 3  kg and <12.00 × 10 3  kg of 305-day milk production), DMP3 (dams with ≥12.00 × 10 3  kg and <14.00 × 10 3  kg of 305-day milk production), DMP4 (dams with ≥14.00 × 10 3  kg and <16.00 × 10 3  kg of 305-day milk production) and DMP5 (dams with ≥16.00 × 10 3  kg of 305-day milk production). In study I, data of birth weight, milk yield and reproductive variables of 14,536 offspring born to lactating dams and corresponding data of DMP were retrieved. In study II, blood samples (n = 339) were collected from offspring in various categories of DMP for measurement of serum AMH. Offspring were heavier at birth in DMP4 and DMP5 categories than DMP1 and DMP2 categories (P < 0.05). Milk yield of offspring increased as DMP elevated (P < 0.05); however, offspring in DMP1 and DMP2 categories produced higher milk as compared with their dams during primiparity (P < 0.05) whereas offspring in DMP3, DMP4 and DMP5 categories produced less milk as compared with their dams during primiparity (P < 0.05). Milk fat to protein ratio during the first month of lactation was greater in DMP4 and DMP5 categories than DMP1 category (P < 0.05). Offspring of DMP4 and DMP5 categories were inseminated and conceived at younger ages than offspring of DMP1 category during nulliparity (P < 0.05). Calving to conception interval was longer in DMP5 than DMP1 category in primiparous offspring (P < 0.05), but concentration of AMH did not differ among various categories of DMP (P > 0.05). In conclusion, dams with greater level of milk production produced heavier offspring with higher milk yield but worse transgenerational improvement in milk production and diminished reproductive performance, which were seemingly under higher pressure of negative energy balance during the first month of lactation., Competing Interests: Declaration of competing interest The authors have no conflict of interest to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)