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Farmer C, Palin MF. Providing domperidone throughout lactation enhances sow lactation performance. J Anim Sci 2021; 99:6310167. [PMID: 34175933 DOI: 10.1093/jas/skab200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/25/2021] [Indexed: 11/13/2022] Open
Abstract
The goal of this project was to determine the effects of domperidone given throughout lactation on hormonal and metabolic status, lactational performance, and gene expression in mammary epithelial cells of sows. Second parity sows were divided in two treatment groups: 1) daily intramuscular injections with canola oil (Control, CTL, n = 24), or 2) daily intramuscular injections with 0.5 mg/kg body weight (BW) of domperidone (DOMP, n = 23). Injections were given at 08h05 starting the day after farrowing until weaning. Over the first 4 d of treatment, DOMP sows also received 0.5 mg/kg BW of domperidone per os twice daily, whereas CTL sows were fed the vehicle. Litter size was standardized to 11 ± 1 within 24 h of birth and piglets were weighed at birth, 24 h postpartum, and on days 7, 22 (weaning on day 23), 35, and 56. Sow feed intake was recorded daily. Representative milk samples were obtained aseptically on day 21 of lactation from 15 sows per treatment for compositional analyses and milk fat globules were used to measure mRNA abundances of various genes. Jugular blood samples were obtained from all sows on days 2, 8, 16, and 23 of lactation to measure concentrations of prolactin, insulin-like growth factor-1 (IGF-1), leptin, adiponectin, insulin, glucose, urea, and free fatty acids (FFA). Concentrations of prolactin (P < 0.001) and FFA (P < 0.01) were increased in DOMP compared with CTL sows, whereas concentrations of insulin were decreased (P < 0.05). Urea concentrations were increased by treatment (P < 0.05) on days 16 and 23 of lactation, and those of IGF-1 were increased (P < 0.01) on day 16. Piglets from DOMP sows were heavier than those from CTL sows on day 22 (P < 0.01). Milk composition was unaffected by treatment. The mRNA abundance in milk fat globules for casein beta and whey acidic protein were lower (P ≤ 0.05) in DOMP than CTL sows. The long form of the prolactin receptor and the signal transducer and activator of transcription 5A mRNA abundances tended to be lower (P < 0.10) in DOMP than CTL sows. In conclusion, hyperprolactinemia induced by domperidone during lactation affected the endocrine and metabolite status of sows and stimulated growth of their suckling piglets.
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Affiliation(s)
- Chantal Farmer
- Agriculture and Agri-Food Canada, Sherbrooke R & D Centre, 2000 College, Sherbrooke, Québec J1M 0C8, Canada
| | - Marie-France Palin
- Agriculture and Agri-Food Canada, Sherbrooke R & D Centre, 2000 College, Sherbrooke, Québec J1M 0C8, Canada
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Kim KY, Choi YH, Hosseindoust A, Kim MJ, Moturi J, Kim TG, Song CH, Lee JH, Chae BJ. Effects of free feeding time system and energy level to improve the reproductive performance of lactating sows during summer. JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2020; 62:356-364. [PMID: 32568269 PMCID: PMC7288228 DOI: 10.5187/jast.2020.62.3.356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/27/2020] [Accepted: 04/06/2020] [Indexed: 11/21/2022]
Abstract
The reproductive performance of lactating sows was investigated by using
different feeding methods including conventional feeding (CF, 3 times/d) or free
feeding (FF), and different dietary energy level including low energy (LE:
3,300) or high energy (HE: 3,400 kcal/kg) during the hot season. A total of
twenty-eight crossbred (Yorkshire × Landrace) sows were distributed into
four treatments as a 2 × 2 factorial arrangement. Sows in the FF group
showed lower body weight and backfat loss (p < 0.05)
compared with the CF group. Backfat loss during lactation was lower
(p < 0.05) in sows fed HE diet than in that fed LE
diet. There were no significant differences in litter survival rate and weaning
to estrus interval, but the litter weight at weaning was improved
(p < 0.05) in FF and HE sows. Hence, it is concluded
that using the free-feeding system or increased dietary energy density leads to
improved sow performance during hot ambient temperature.
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Affiliation(s)
- Kwang Yeol Kim
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Yo Han Choi
- Department of Animal Resources Development Swine Science Division, RDA, Cheonan 31000, Korea
| | - Abdolreza Hosseindoust
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Min Ju Kim
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Joseph Moturi
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Tae Gyun Kim
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Chang Hyun Song
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Jun Hyung Lee
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Byung Jo Chae
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
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3
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Zhang H, Chen T, Xiong J, Hu B, Luo J, Xi Q, Jiang Q, Sun J, Zhang Y. MiR-130a-3p Inhibits PRL Expression and Is Associated With Heat Stress-Induced PRL Reduction. Front Endocrinol (Lausanne) 2020; 11:92. [PMID: 32194503 PMCID: PMC7062671 DOI: 10.3389/fendo.2020.00092] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 02/13/2020] [Indexed: 01/14/2023] Open
Abstract
MicroRNAs (MiRNAs) play critical roles in the regulation of pituitary function. MiR-130a-3p has previously been found to be down-regulated in prolactinoma, but its roles in prolactin (PRL) regulation and the underlying mechanisms are still unclear. Heat stress has been shown to induce alteration of endocrine hormones and miRNAs expressions. However, there is limited information regarding the emerging roles of miRNAs in heat stress response. In this study, we transfected miR-130a-3p mimic into the pituitary adenoma cells (GH3 cells) to investigate the function of miR-130a-3p in regulating PRL. Our results showed that miR-130a-3p overexpression significantly decreased the PRL expression at both mRNA and protein levels. Subsequently, estrogen receptor α (ERα) was identified as a direct target of miR-130a-3p by bioinformatics prediction, luciferase reporter assay and western blotting assay. Furthermore, the inhibition of ERα caused by estrogen receptor antagonist significantly reduced the PRL expression. Overexpression of ERα rescued the suppressed expression of PRL caused by miR-130a-3p mimic. Besides, we also studied the effect of heat stress on PRL and miRNAs expressions. Interestingly, we found that heat stress reduced PRL and ERα expressions while it increased miR-130a-3p expression both in vitro and in vivo. Taken together, our results indicate that miR-130a-3p represses ERα by targeting its 3'UTR leading to a decrease in PRL expression, and miR-130a-3p is correlative with heat stress-induced PRL reduction, which provides a novel mechanism that miRNAs are involved in PRL regulation.
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Affiliation(s)
- Haojie Zhang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Ting Chen
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Engineering & Research Center for Woody Fodder Plants, South China Agricultural University, Guangzhou, China
| | - Jiali Xiong
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Baoyu Hu
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Junyi Luo
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Qianyun Xi
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Engineering & Research Center for Woody Fodder Plants, South China Agricultural University, Guangzhou, China
| | - Qingyang Jiang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Jiajie Sun
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Engineering & Research Center for Woody Fodder Plants, South China Agricultural University, Guangzhou, China
- *Correspondence: Jiajie Sun
| | - Yongliang Zhang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, China
- Guangdong Engineering & Research Center for Woody Fodder Plants, South China Agricultural University, Guangzhou, China
- Yongliang Zhang
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Zhang H, Hu B, Xiong J, Chen T, Xi Q, Luo J, Jiang Q, Sun J, Zhang Y. Genomewide analysis of circular RNA in pituitaries of normal and heat-stressed sows. BMC Genomics 2019; 20:1013. [PMID: 31870281 PMCID: PMC6929353 DOI: 10.1186/s12864-019-6377-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 12/08/2019] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND As a newly characterized type of noncoding RNA, circular RNA (circRNA) has been shown to have functions in diverse biological processes of animals. It has been reported that several noncoding RNAs may regulate animals' response to heat stress which can be easily induced by hyperthermia in summer. However, the expression and functions of circRNAs in the pituitary of sows and whether they participate in heat stress adaption are still unclear. RESULTS In this study, we found that high temperature over the thermoneutral zone of sows during the summer increased the serum heat shock protein 70 (HSP70) level, decreased the superoxide dismutase (SOD) vitality and prolactin (PRL) concentration, and induced heat stress in sows. Then, we explored circRNA in the pituitary of heat-stressed and normal sows using RNA sequencing and bioinformatics analysis. In total, 12,035 circRNAs were detected, with 59 circRNAs differentially expressed, including 42 up-regulated and 17 down-regulated circRNAs in pituitaries of the heat-stressed sows. Six randomly selected circRNAs were identified through reverse transcription PCR followed by DNA sequencing and other 7 randomly selected differentially expressed circRNAs were verified by quantitative real-time PCR analysis. The predicted target genes regulated by circRNAs through sponging microRNAs (miRNAs) were enriched in metabolic pathway. Furthermore, the predicted circRNA-miRNA-mRNA interactions showed that some circRNAs might sponge miRNAs to regulate pituitary-specific genes and heat shock protein family members, indicating circRNA's roles in pituitary hormone secretion and heat stress response. CONCLUSIONS Our results provided a meaningful reference to understand the functions of circRNA in the porcine pituitary and the mechanisms by which circRNA may participate in animals' response to heat stress.
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Affiliation(s)
- Haojie Zhang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, Guangdong, 510642, People's Republic of China
| | - Baoyu Hu
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, Guangdong, 510642, People's Republic of China
| | - Jiali Xiong
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, Guangdong, 510642, People's Republic of China
| | - Ting Chen
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, Guangdong, 510642, People's Republic of China
| | - Qianyun Xi
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, Guangdong, 510642, People's Republic of China
| | - Junyi Luo
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, Guangdong, 510642, People's Republic of China
| | - Qingyan Jiang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, Guangdong, 510642, People's Republic of China
| | - Jiajie Sun
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, Guangdong, 510642, People's Republic of China.
| | - Yongliang Zhang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Wushan Road, Tianhe District, Guangzhou, Guangdong, 510642, People's Republic of China.
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Choi Y, Moturi J, Hosseindoust A, Kim M, Kim K, Lee J, Song C, Kim Y, Chae B. Night feeding in lactating sows is an essential management approach to decrease the detrimental impacts of heat stress. JOURNAL OF ANIMAL SCIENCE AND TECHNOLOGY 2019; 61:333-339. [PMID: 31844543 PMCID: PMC6906131 DOI: 10.5187/jast.2019.61.6.333] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/08/2019] [Accepted: 10/21/2019] [Indexed: 01/18/2023]
Abstract
The present study investigated the litter performance of multiparous sows had
different feeding frequencies during summer season. A total of 60 crossbred
multiparous sows was allotted to one of two treatments based on body weight (BW)
according to a completely randomized design. Two different feeding frequencies
based on NRC (National Research Council) were applied as conventional feeding
(T1; 2 kg per meal at 06:00, 11:00, and 17:00) and night feeding (T2; 1.5 kg per
meal at 06:00, 11:00, 17:00, and 2 kg at 22:00). Sows in T2 treatment had lower
(p < 0.05) BW changes during lactation. The backfat
thickness change of sows was decreased in T2 treatment during lactation
(p < 0.05). The daily feed intake differed significantly
between T1 and T2 with increased feed intake of the T2 group at 5.47 kg/d to
5.14 kg/d in the T1 group (p < 0.05). There was a
significant difference in total weight of weaned piglets between T1 (70.50 kg)
and T2 (74.34 kg). A greater total litter weight gain was observed in sows in T2
treatment. Night feeding is suggested for lactating sows with significant
beneficial effects on litter growth during summer season.
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Affiliation(s)
- YoHan Choi
- Swine Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Korea
| | - Joseph Moturi
- College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | | | - MinJu Kim
- College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - KwangYeol Kim
- College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - JunHyung Lee
- College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - ChangHyun Song
- College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - YoungHwa Kim
- Swine Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Korea
| | - ByungJo Chae
- College of Animal Life Sciences, Kangwon National University, Chuncheon 24341, Korea
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6
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Rigo E, Nascimento MM, Silva N. Desempenho e termorregulação de porcas lactantes alojadas em diferentes localizações no interior de um galpão com sistema de resfriamento evaporativo em ambiente tropical. ARQ BRAS MED VET ZOO 2019. [DOI: 10.1590/1678-4162-11370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- E.J. Rigo
- Universidade Federal de Uberlândia, Brazil
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8
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Farmer C, Mathews AT, Hovey RC. Using domperidone to induce and sustain hyperprolactinemia in late-pregnant gilts. Domest Anim Endocrinol 2019; 66:14-20. [PMID: 30205268 DOI: 10.1016/j.domaniend.2018.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 11/20/2022]
Abstract
Prolactin controls mammary development as well as the lactogenic and galactopoietic processes in sows and increasing prolactin during gestation can augment milk yield. The dopamine receptor antagonist domperidone can increase circulating prolactin concentrations in pigs, but the ideal dose to achieve sustained hyperprolactinemia remains unknown. An experiment was performed to develop a protocol for using domperidone in studies of rapid and sustained hyperprolactinemia in late-pregnant gilts. On day 90 of gestation, gilts were divided into 4 groups: (1) intramuscular (IM) injections of canola oil (3 mL, controls [CTL], n = 9), (2) IM injections with 0.1 mg/kg BW of domperidone (low [LO], n = 8), (3) IM injections with 0.5 mg/kg BW of domperidone (medium [ME], n = 11), and (4) IM injections with 1.0 mg/kg BW of domperidone (high [HI], n = 11). Injections were given daily at 8:05 from days 90 to 109 of gestation. Treated gilts also received domperidone per os (0.5 mg/kg BW) at 8:00 and 20:00 on days 89, 90, and 91 of gestation. Three jugular blood samples were collected from all gilts at 6-h intervals on days 89, 90, and 91 of gestation, then twice daily on days 92, 93, and 94. Thereafter, samples were obtained at 8:00 every other day until day 114 of gestation. Blood was sampled serially from 9 CTL and 11 HI gilts on days 89 and 94 of gestation. On day 89 of gestation, prolactin concentrations for LO, ME, and HI gilts increased within 6 h of domperidone per os (P < 0.001). From days 89 until 93 of gestation, the area under the curve (AUC) for LO, ME, and HI gilts was greater than that for CTL gilts (P < 0.001), whereas from days 89 until 114, ME and HI gilts had greater AUC than CTL and LO gilts (P < 0.05). Results demonstrate that the combination of per os treatment with IM injections of 0.5 mg/kg of domperidone in an oil emulsion leads to the rapid and sustained release of prolactin over 24 d in late-pregnant gilts. Higher doses of domperidone failed to further increase circulating prolactin levels. These findings provide a useful strategy to induce sustained hyperprolactinemia in late-pregnant gilts.
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Affiliation(s)
- C Farmer
- Agriculture and Agri-Food Canada, Sherbrooke Research and Development Centre, Sherbrooke, Canada.
| | - A T Mathews
- Department of Animal Science, University of California Davis, Davis, CA, USA
| | - R C Hovey
- Department of Animal Science, University of California Davis, Davis, CA, USA
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Choi Y, Hosseindoust A, Kim J, Lee S, Kim M, Kumar A, Kim K, Kim YH, Chae BJ. An overview of hourly rhythm of demand-feeding pattern by a controlled feeding system on productive performance of lactating sows during summer. ITALIAN JOURNAL OF ANIMAL SCIENCE 2018. [DOI: 10.1080/1828051x.2018.1438214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- YoHan Choi
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon, Republic of Korea
| | - Abdolreza Hosseindoust
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon, Republic of Korea
| | - JinSoo Kim
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon, Republic of Korea
| | - SuHyup Lee
- Department of Swine and Poultry Science, National College of Agriculture and Fisheries, Jeonju, Republic of Korea
| | - MinJu Kim
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon, Republic of Korea
| | - Alip Kumar
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon, Republic of Korea
| | - KwangYeol Kim
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon, Republic of Korea
| | - Young Hwa Kim
- Department of Animal Resources Development Swine Science Division, RDA, Cheonan-si, Chungnam, Republic of Korea
| | - Byung Jo Chae
- Department of Animal Resources Science, College of Animal Life Sciences, Kangwon National University, Chuncheon, Republic of Korea
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Farmer C. Altering prolactin concentrations in sows. Domest Anim Endocrinol 2016; 56 Suppl:S155-64. [PMID: 27345313 DOI: 10.1016/j.domaniend.2015.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/05/2015] [Accepted: 11/12/2015] [Indexed: 12/28/2022]
Abstract
Prolactin has a multiplicity of actions, but it is of particular importance in gestating and lactating animals. In sows, it is involved in the control of mammary development and also holds essential roles in the lactogenic and galactopoietic processes. Furthermore, low circulating concentrations of prolactin are associated with the agalactia syndrome. The crucial role of prolactin makes it important to understand the various factors that can alter its secretion. Regulation of prolactin secretion is largely under the negative control of dopamine, and dopamine agonists consistently decrease prolactin concentrations in sows. On the other hand, injections of dopamine antagonists can enhance circulating prolactin concentrations. Besides pharmacologic agents, many other factors can also alter prolactin concentrations in sows. The use of Chinese-derived breeds, for instance, leads to increased prolactin concentrations in lactating sows compared with standard European white breeds. Numerous husbandry and feeding practices also have a potential impact on prolactin concentrations in sows. Factors, such as provision of nest-building material prepartum, housing at farrowing, high ambient temperature, stress, transient weaning, exogenous thyrotropin-releasing factor, exogenous growth hormone-releasing factor, nursing frequency, prolonged photoperiod, fasting, increased protein and/or energy intake, altered energy sources, feeding high-fiber diets, sorghum ergot or plant extracts, were all studied with respect to their prolactinemic properties. Although some of these practices do indeed affect circulating prolactin concentrations, none leads to changes as drastic as those brought about by dopamine agonists or antagonists. It appears that the numerous factors regulating prolactin concentrations in sows are still not fully elucidated, and that studies to develop novel applicable ways of increasing prolactin concentrations in sows are warranted.
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Affiliation(s)
- C Farmer
- Agriculture and Agri-Food Canada, Dairy and Swine Research and Development Centre, Sherbrooke, QC, J1M 0C8, Canada.
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Abstract
An understanding of the mechanisms regulating milk yield in sows is crucial for producers to make the best management decisions during lactation. Suckling of mammary glands by piglets is one factor that is essential for development of these glands during lactation and for the maintenance of lactation in sows. The process of mammary development is not static as the majority of it takes place in the last third of gestation, continues during lactation, is followed by involution at weaning and starts over again in the next gestation. During involution, the mammary glands undergo a rapid and drastic regression in parenchymal tissue, and this can also occur during lactation if a gland is not suckled regularly. Indeed, the pattern of regression is similar for glands that involute at weaning or during lactation. Suckling during 12 to 14 h postpartum is insufficient to maintain lactation and the process of involution that occurs in early lactation is reversible within 1 day of farrowing but is irreversible if a gland is not used for 3 days. However, milk yield from a gland which is 'rescued' within the first 24 h remains lower throughout lactation. Suckling does not only affect milk yield in the ongoing lactation, but it also seems to affect that of the next lactation. Indeed, non-suckling of a mammary gland in first-parity sows decreased development and milk yield of that gland in second parity. Nursing behaviour of piglets in early lactation was also affected, where changes were indicative of piglets in second parity being hungrier when suckling glands that were not previously used. It is not known, however, if the same effects would be seen between the second and third lactation. Furthermore, the minimum suckling period required to ensure maximal milk yield from a gland in the next lactation is not known. This review provides an update on our current knowledge of the importance of suckling for mammary development and milk yield in swine.
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