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Background: The Gyr breed is widely used in Colombian low tropic dairy production systems. During the last 10 years, the Asociación Colombiana de Criadores de Ganado Cebú† - ASOCEBU, has been leading a dairy milk control program which led to the creation of a dataset that permits to carry out the first analysis of milk yield in Gyr cattle in the country using records from several herds. Objectives: To study milk production dynamics of Gyr cattle in the Colombian low tropic through the estimation of lactation curves and four derived production parameters: total milk yield between 5 and 305 days (TMY305), peak milk yield (PMY), days at peak (DP) and persistency (P). Methods: 13,798 daily milk yield records from 1,510 cows performing in 103 herds were used; the total number of lactations was 2,480. Four models were considered: Wood, Wiltmink, Papajcsik & Bordero, and a second-degree polynomial. Mean square error, mean absolute error, mean square error of prediction, Akaike and Bayesian information criteria were used to select the model better describing each lactation using the majority rule, that is, the model selected by most criteria was the chosen one. The shape of each fitted lactation curve was checked using basic results from calculus which permitted the classification of the estimated curves into two groups: typical and atypical; only typical functions were used to compute the four aforementioned production parameters. Results: The second-order polynomial was the model most frequently selected, while the Papajcsik & Bordero model had the lowest frequency. Average TMY305, PMY, DP and P were 3,489.86 kg, 17.28 kg, 57.17 days, and 0.83, respectively, with coefficients of variation: 0.27, 0.21, 0.41, and 0.16. Conclusions: This study permitted to identify individuals with outstanding phenotypic performance. To the best of our knowledge, this is the first study of this kind involving thousands of lactations from Gyr cows performing in several regions of Colombian low tropic.

Summary Background: the allonursing effect on daily milk production (DMP) and total milk production (TMP) has been little explored. Objective: to evaluate the effect of nursing behavior, sex of the calf and parity order (PO) on DMP and TMP of buffalo cows. Methods: 35 buffalo cows and their calves were evaluated. Observations were performed monthly (three consecutive days) from May to November. The nursing behavior was characterized as: 1) Isolated filial nursing (IFN); 2) Collective filial nursing (CFN), and 3) Non-filial nursing (NFN). Cows were grouped into four categories to study the effects of nursing behavior on DMP and TMP: 1) Non-permissive (NP); 2) Filial permissive (FP); 3) Filial and collective filial permissive (FCFP); and 4) Filial, collective filial and non-filial permissive (FCFNFP). DMP was recorded three days per month and TMP was calculated as DMP*270 days of lactation. Results: sex of the calf and second and third PO had an effect on nursing behavior (p<0.05). DMP and TMP were significantly affected by calf sex and nursing behavior (p<0.05). PO had no effect on DMP and TMP. Conclusion: our results suggest that nursing behavior is associated with milk production in buffalo cows. Buffalo cows that accept all types of nursing behavior were had the highest DMP and TMP. Sex of the calf influenced nursing behavior, DMP, and TMP, so that buffalo cows with male calves displayed more frequent allonursing behavior and yielded more milk. Resumo Antecedentes: o comportamento de alo-amamentação sobre a produção de leite diária (DMP) e produção de leite total (TMP) tem sido pouco explorado. Objetivo: avaliar o efeito do comportamento de amamentação, sexo dos bezerros e ordem de parto (PO) na DMP e TMP em vacas bubalinas. Métodos: trinta e cinco fêmeas e suas crias foram avaliadas no estudo. As observações foram realizadas mensalmente (três dias consecutivos) de maio a novembro. O comportamento de amamentação foi caracterizado como 1) amamentação filial isolada (IFN); 2) amamentação coletiva filial (CFN) e 3) amamentação não filial (NFN). Para avaliar os efeitos do comportamento da amamentação na DMP e TMP, as vacas bubalinas foram agrupadas em 4 categorias: 1) não permissiva (NP); 2) permissiva filial (FP); 3) permissiva filial e coletiva filial (FCFP) e 4) permissiva filial, coletiva filial e não filial (FCFNFP). A DMP foi registrada três dias para cada mês e a TMP foi calculada como DMP*270 dias de lactação. Resultados: o sexo dos bezerros, a segunda e terceira PO tiveram efeitos no comportamento de amamentação (p<0.05). A DMP e TMP foram significativamente afetadas pelo sexo dos bezerros e comportamento de amamentação (p<0.05). A PO não teve efeito na DMP e TMP. Conclusões: nossos resultados sugerem que o comportamento de amamentação estão associados a produção de leite em vacas bubalinas. As vacas bubalinas que são permissíveis a todos os tipos de amamentações foram aquelas com maior DMP e TMP. O sexo dos bezerros influenciou o comportamento de amamentação, DMP e TMP, sendo que as vacas bubalinas que possuem bezerros machos apresentaram frequente comportamento de alo-amamentação e produziram maiores quantidades de leite. Resumen Antecedentes: el comportamiento del alo-amamantamiento sobre la producción diaria de leche (DMP) y producción total de leche (TMP) ha sido poco explorado. Objetivo: evaluar el efecto del comportamiento de amamantamiento, el sexo del becerro y el orden de parto (PO) en la DMP y TMP de bufalas. Métodos: se evaluaron 35 hembras bufalinas y sus crías. Las observaciones se realizaron mensualmente (durante tres días consecutivos) entre mayo y noviembre. El comportamiento de amamantamiento se caracterizó como: 1) Amamantamiento filial aislado (IFN); 2) Amamantamiento filial colectivo (CFN) y 3) Amamantamiento no filial (NFN). Para evaluar los efectos del comportamiento de amamantamiento en la DMP y TMP, las vacas fueron agrupadas en 4 categorías: 1) No permisivas (NP); 2) Permisiva filial (FP); 3) Permisiva filial y colectiva filial (FCFP) y 4) Permisiva filial, colectiva filial y no colectiva (FCFNFP). La DMP se registró tres días por mes, y la TMP fue calculada como DMP*270 días de lactancia. Resultados: el sexo del becerro, el segundo y tercer PO tuvieron efecto sobre el comportamiento de amamantamiento (p<0.05). La DMP y la TMP se afectaron significativamente por el sexo del becerro y el comportamiento de amamantamiento (p<0.05). El PO no tuvo efecto sobre la DMP y la TMP. Conclusiones: nuestros resultados sugieren que el comportamiento de amamantamiento está asociado a la producción de leche en vacas bubalinas. Las bufalas permisivas a todo tipo de amamantamiento presentaron mayor DMP y TMP. El sexo del becerro influyó en el comportamiento de amamantamiento, en la DMP y en la TMP. Las bufalas con becerro macho presentaron comportamiento de alo-amamantamiento más frecuente y produjeron mayor cantidad de leche.

We evaluated the proportion of fatty acid groups, with an emphasis on hypercholesterolaemic fatty acids, in the milk of 25 Holstein cows during the 1st period of lactation in relation to their negative energy balance (NEB). Sampling of each cow's milk started on the 7th day after calving. Milk samples (n = 425) were collected at 7-day periods during the first 17 weeks of lactation. The proportion (%) of saturated (SFA), hypercholesterolaemic (HCFA), volatile (VFA), unsaturated (UFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids in the milk fat was determined. Body condition score and fat to protein ratio in milk were applied for precise determination of the NEB breakpoint during the observed period. The effects of parity, NEB, regression on lactation week and fat to protein ratio were evaluated using SAS 9.3. Milk contained a lower proportion of SFA as well as equally higher UFA (+/- 2.13%; P less than 0.01) during the NEB period. The overcoming of NEB caused an increase in SFA, however, and simultaneously a significant decline in total HCFA (-1.86%; P less than 0.01) as well as main MUFA (-1.81%, P less than 0.05). The results document the necessity of increasing Holstein cow robustness to meet the production conditions in dairy farms in relation to the requirement of higher nutrient quality as well as the potential health benefits of cow's raw milk for consumers.

We investigated the effect of the estrogen receptor (ESR) gene on growth and reproductive traits in four Large White-based commercial pig lines. A total of 9,015 litter records from 4,262 sows genotyped at the ESR locus were analyzed to determine whether ESR influenced total number born (TNB) or number born alive (NBA). Teat number (TN), test ADG, ADFI, feed:gain ratio (F/G), and ultrasonic backfat (B F) were also analyzed to determine effects of ESR. The TNB and NBA were increased per favorable allele of ESR (P .01) with additive effects of .42 (.31) and .39 (.31) pigs/litter in the first parity (later parities), respectively. Dominance effects were near zero in parity one, but they were .16 and .14 pigs for TNB and NBA, respectively, in later parities (P .05). A favorable additive pleiotropic effect was detected for BF (P .001;-.11 mm per copy of the favorable litter size allele). There were no detectable effects on ADG or F/G (P .10), although ADF was reduced 18 g/d per copy of the favorable litter size allele (P .05). Average TN was 13.1 for pigs carrying the favorable litter size allele vs 13.2 for noncarriers (P .05). Marker-assisted selection using ESR is warranted to increase litter size in the Large White-based lines considered here and will be of considerable economic value to pork producers